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Systemic anaphylaxis is a potentially life-threatening clinical syndrome resulting from the release of biologically active substances such as histamine or prostaglandins upon a target organ. The aims of our study were to analyze clinical data, causative agents and follow-up in subjects with severe anaphylaxis. Of 5689 subjects who were referred from May 1994 through October 1996 to the allergy-immunology out-patient clinic of the University of Berne, 118 (2.1%; 68 females and 50 males; mean age 41 years) had experienced severe systemic anaphylaxis with hypotension, loss of consciousness or shock. 104 individuals (88.1%) showed accompanying dermal symptoms, 85 (72.0%) respiratory and 52 (44.1%) gastrointestinal signs. Causative agents were identified in 93.2% of these attacks; they included drugs (33.9%), insect stings (23.7%), foods (18.6%), exercise (8.5%), latex (7.6%), and immunotherapy (0.9%) with pollen extracts. A suspected cause could not be determined in 8 subjects. Atopy was present in 64 individuals (54%). Prior to the index anaphylaxis, 21 of 110 subjects (19.1%) with an identified cause had experienced more than one episode of anaphylaxis. Follow-up survey showed that 29 of these 110 individuals (26.4%) were accidentally reexposed to the causative agents. 19 of 24 patients (79.2%) used their emergency kits, while 5 were not equipped with. Only one severe systemic reaction occurred in a subject who intentionally reexposed himself to the identified cause of anaphylaxis. Besides cardiovascular symptoms, systemic anaphylaxis most often involves the skin and respiratory tract. Since prevention of anaphylaxis focuses upon avoidance of precipitating factors, all individuals with anaphylaxis should be referred to an allergologist for identification of the causative agents. The cause of anaphylaxis could be determined in the majority of patients with anaphylaxis. However, unexpected exposures are frequent. Thus, all patients who have had one or more episodes of anaphylaxis should carry an emergency kit for self-administration, and should be instructed in its use.

Background: The chemokine eotaxin is produced at sites of allergic inflammation, binds selectively to the chemokine receptor CCR3 and attracts eosinophil and basophil leukocytes, which express high numbers of this receptor. Responses of T lymphocytes to eotaxin have not been reported so far. We have investigated the expression of CCR3 in T lymphocytes and analysed the properties and in vivo distribution of T lymphocytes expressing this receptor., Results: In search of chemokine receptors with selective expression in T lymphocytes, we have isolated multiple complementary DNAs (cDNAs) encoding CCR3 from a human CD4+ T-cell cDNA library. T-lymphocyte clones with selectivities for protein and non-protein antigens were analysed for expression of CCR3 and production of Th1- and Th2-type cytokines. Of 13 clones with surface CCR3, nine secreted enhanced levels of interleukin-4 and/or interleukin-5, indicating that CCR3 predominates in Th2-type lymphocytes. CCR3+ T lymphocytes readily migrated in response to eotaxin, and showed the characteristic changes in cytosolic free calcium. Immunostaining of contact dermatitis, nasal polyp and ulcerative colitis tissue showed that CCR3+ T lymphocytes are recruited together with eosinophils and, as assessed by flow cytometry, a large proportion of CD3+ cells extracted from the inflamed skin tissue were CCR3+. By contrast, CCR3+ T lymphocytes were absent from tissues that lack eosinophils, as demonstrated for normal skin and rheumatoid arthritis synovium., Conclusions: We show that T lymphocytes co-localizing with eosinophils at sites of allergic inflammation express CCR3, suggesting that eotaxin/CCR3 represents a novel mechanism of T-lymphocyte recruitment. These cells are essential in allergic inflammation, as mice lacking mature T lymphocytes were insensitive to allergen challenge. Surface CCR3 may mark a subset of T lymphocytes that induce eosinophil mobilization and activation through local production of Th2-type cytokines.

To analyze whether and how T cells are involved in drug allergies, we analyzed the drug-induced activation of T cell subsets, T cell receptor V-beta usage and cytokine secretion of T cells from the peripheral blood of drug-allergic individuals. The specificity of the T cells was demonstrated by specific restimulation of drug specific clones. We found that drugs which do not need to be metabolized to become immunogenic (haptens like penicillin G) can stimulate CD4+ and CD8+ T cells in vitro. The T cell response to penicillin can be oligoclonal (use of a certain T cell receptor Vbeta only) or polyclonal. Only polyclonal T cell lines were cross-reactive with other beta-lactam antibiotics. Sulfamethoxazole and lidocaine are thought to gain their ability to bind to proteins by intracellular drug metabolism. They were found to stimulate CD4+ and CD8+ T cells in vitro, and some reactive T cell lines were oligoclonal. The majority of lidocaine-specific clones secreted rather high amounts of IL-5 and IL-4 after PMA/ionomycin stimulations (Th2-like), but some CD4+ and all CD8+ clones had a Th1-like phenotype (high INF-gamma and TNF-alpha). The data clearly demonstrate the existence of drug-specific alphabeta+ T cells in the circulation of drug-allergic individuals and reveal a great heterogeneity of T-cell-mediated responses. Further studies are needed to correlate the type of T cell response to the clinical picture, which can be quite heterogeneous.

The immune system has different possible ways of reacting to an antigen. The choice of an appropriate immune response is determined by the manner of antigen presentation, the amount of antigen, the localization of antigen uptake, the type of antigen presenting cell, the genetic predisposition of the individual and the presence of certain cytokines released by antigen presenting or other inflammatory cells. An immune response which is not not appropriate can lead to clinical symptoms or insufficient clearance of an infectious agent. This is well-illustrated in the example of lepra lepromatosa (insufficient, since humoral immune response to an intracellular agent) or lepra tuberculosa (complete clearance of Mycobacterium leprae). A decisive step for the type of immune response is the stimulation of different T-cell subpopulations. CD4 or CD8 T-cells can be further subdivided by a distinct cytokine production. So-called TH1 cells predominantly produce cytokines, which stimulate a cellular immune response (IFN gamma, IL-12, IL-2). In contrast, TH2 cells predominantly produce IL-4 and IL-5. These cytokines boost an IgE-mediated allergic reaction and inflammation. Although the TH1/ TH2 distinction is frequently not absolute, as overlaps can frequently be observed, this classification is useful for better understanding of immune reactions in various diseases. Moreover, since TH1- and TH2-related cytokines act antagonistically, therapeutic strategies are under development which strengthen e.g. a TH2 immune response in TH1 dominated diseases and vice versa.

Hypersensitivity syndromes are severe drug induced side effects with skin rashes, fever and/or multiorgan-system abnormalities which are not pharmacologically related. They are well known in relation to allopurinol, anticonvulsants and sulfonamides, but only rarely described with other drugs. These reactions are considered to be immune-mediated but the precise mechanisms are not completely understood. Clinical features, which resemble an EBV infection, and some immunological studies suggest that T-cell mediated immunity is involved in the pathogenesis of this rare disease. In the literature, allopurinol and anticonvulsant hypersensitivity syndromes are clinically well characterized entities, while the definition of hypersensitivity syndrome elicited by other drugs is rather confusing. We present two patients, one with sulfamethoxazole- and one with allopurinol-induced hypersensitivity syndrome. In both cases a lymphocyte transformation test (LTT) was performed and we analyzed the T-cell activation parameters CD25 and HLA-DR on CD4- and CD8- T-cells to demonstrate in vivo activation of T-cells during the active disease. Both patients show increased activation of T-cells with elevated levels of HLA-DR on CD8+ cells. The T-cell activation correlated with the clinical course. Our data support an immunological pathogenesis for hypersensitivity syndromes and the concept that drug specific T-cells are involved in hypersensitivity syndromes.

Background: The diagnosis of a drug allergy is mainly based upon a very detailed history and the clinical findings. In addition, several in vitro or in vivo tests can be performed to demonstrate a sensitization to a certain drug. One of the in vitro tests is the lymphocyte transformation test (LTT), which can reveal a sensitization of T-cells by an enhanced proliferative response of peripheral blood mononuclear cells to a certain drug., Objective: To evaluate the sensitivity and specificity of the LTT, 923 case histories of patients with suspected drug allergy in whom a LTT was performed were retrospectively analysed., Methods: Based on the history and provocation tests, the probability (P) of a drug allergy was estimated to be > 0.9, 0.5-0.9, 0.1-0.5 or < 0.1, and was put in relation to a positive or negative LTT., Results: Seventy-eight of 100 patients with a very likely drug allergy (P > 0.9) had a positive LTT, which indicates a sensitivity of 78%. If allergies to betalactam-antibiotics were analysed separately, the sensitivity was 74.4%. Fifteen of 102 patients where a classical drug allergy could be excluded (P < 0.1), had nevertheless a positive LTT (specificity thus 85%). The majority of these cases were classified as so-called pseudo-allergic reaction to NSAIDs. Patients with a clear history and clinical findings for a cotrimoxazole-related allergy, all had a positive LTT (6/6), and in patients who reacted to drugs containing proteins, sensitization could be demonstrated as well (i.e. hen's egg lysozyme, 7/7). In 632 of the 923 cases, skin tests were also performed (scratch and/or epicutaneous), for which we found a lower sensitivity than for the LTT (64%), while the specificity was the same (85%)., Conclusion: Although our data are somewhat biased by the high number of penicillin allergies and cannot be generalized to drug allergies caused by other compounds, we conclude that the LTT is a useful diagnostic test in drug allergies, able to support the diagnosis of a drug allergy and to pinpoint the relevant drug.

41 subjects with highly elevated IgG anticardiolipin antibody (aCL) titers (> 30 GPL-U/ml) were retrospectively evaluated regarding underlying disease, clinical symptoms, and in particular the influence of drugs on aCL titer and clinical symptoms. Whereas 31/41 (76%) fulfilled the criteria for an antiphospholipid antibody syndrome (APS), 10 (24%) did not. About half (47%) of the patients had an autoimmune disease (mainly systemic lupus erythematosus). 26 (63%) had had recurrent thrombophilic events, 3 (7%) recurrent spontaneous abortions and 10 (24%) associated thrombocytopenia. 8/34 (23%) subjects followed up over 6-42 months had a thrombophilic complication again. 6/16 (37%) developed deep venous thrombosis in spite of oral anticoagulation (INR 1.5-3.0), one of three under acetylsalicylic acid treatment and only one subject without therapy. ACL titer decreased (> 12 U/ml) in 20/34 subjects (59%) during the follow-up period, mainly in patients under immunosuppressive treatment due to the underlying autoimmune disease. In comparison with 5/14 subjects (36%) with consistently high aCL, only 3/20 (15%) with decreasing aCL developed thrombosis. Patients treated by immunosuppressive agents had a higher incidence of decreasing aCL than those without. This investigation indicates that a high titer of aCL in asymptomatic subjects does not justify prophylactic anticoagulation therapy. However, if a history of recurrent deep venous thromboses or pulmonary embolisms is established, long-term anticoagulation therapy should be maintained at or above the international normalized ratio (INR) of 3. ACL titers in subjects with an autoimmune disease may decline, as a result of immunosuppressive treatment or otherwise, and this decline is associated with a lower incidence of thrombophilic disorders.

Objective and Design: To better understand how T cells react to small compounds, we investigated the in vitro T cell reactivity to drugs from drug allergic patients., Material and Subjects: Peripheral blood mononuclear cells (PBMC) of three drug allergic individuals were stimulated in vitro by different drugs., Methods: Proliferation was assayed by 3H-thymidine incorporation. Upregulation of activation parameter on T cells was done by immunofluorescence and cytokine release determined via standard ELISA., Results: Drugs can stimulate both CD4 and CD8 T-cell subsets. PenG-stimulated PBMC showed a heterogenous cytokine pattern and clones secreted high amounts of INF gamma. In contrast, sulfamethoxazole and lidocaine-stimulated PBMC secreted high levels of IL-5 and lidocaine-specific clones can be Th1 or Th2-like., Conclusion: Drug specific T cells play a pivotal role in drug hypersensitivity reactions, both by regulating the immune response and probably also as specific effector cells with different patterns of cytokine release.

The stimulation of activated T cells with soluble peptides or peptide-pulsed T-APC in the absence of professional APC can anergize peptide-specific T cells. Here, we studied human T cell clones (TCCs) that either proliferate (T-responder) or do not proliferate (T-nonresponder) to activated T cells as antigen-presenting cells (APC) and investigated the efficacy of anergy induction in these two types of TCCs. The TCCs were specific to the p30 peptide from tetanus toxoid and secreted either a Th0- or a Th1-like cytokine pattern. To induce anergy, the TCCs were first stimulated by addition of the peptides directly to the cell cultures without additional APC (T-APC). Anergy was detected by restimulating these TCCs on professional B-APC. The proliferation, production of cytokines (IL2, IFN-gamma, IL4, IL5, IL10), and the cytotoxicity were measured after the first and second stimulation and compared with nonanergized control cells. Priming of TCCs by T-APC (anergy induction) resulted in an elevated production of IL4. This cytokine shift was also seen in the T-nonresponder TCC despite no induced proliferation. Th1-like TCCs retained their cytotoxicity after anergy induction. In contrast to cells first activated by B-APC, the restimulation of TCCs primed by T-APC lead to a drastic reduction of proliferation and cytokine production for both T-responder and T-nonresponder TCCs. The functional down-regulation of TCCs mediated by soluble peptides could be overcome by addition of IL2, but not by IL1 or IL4. We concluded that the induction of T-cell anergy does not require cell proliferation.

Background: Rapid clinical tolerance can be induced over several hours by very fast bee venom immunotherapy (VIT) protocols., Objective: To investigate the mechanisms underlying VIT we examined the changes of blood basophil responsiveness during VIT., Methods: Seven bee venom allergic patients with a history of severe systemic reactions after a bee sting were investigated. A cumulative dose of 111.1 micrograms bee venom (BV) was administered sc over 3.5 h under intensive care conditions according to an ultra-rush protocol. The release of histamine and the formation of leukotrienes in response to BV, major BV allergen Phospholipase A2 (PLA), IgE receptor cross-linking with the use of monoclonal antibodies against IgE and IgE receptor, as well as IgE independent activation in response to C5a were determined in vitro before and after ultra-rush VIT., Results: We demonstrated a decrease of total histamine in peripheral blood leucocytes just after VIT. Histamine release in response to all the stimuli used is not affected by ultra-rush VIT, if expressed as per cent release of total histamine. However, the absolute amount product released in response to stimulation was decreased, particularly with allergen (BV, PLA). We also found a significant reduction of LTC4 formation after VIT in samples stimulated with specific allergen (BV, PLA)., Conclusion: Blood basophils are a target for VIT, which induces impaired release of both preformed and newly generated mediators. However, we believe the basic mechanisms of rapid clinical tolerance induced by ultra-rush VIT remain to be investigated.

Background: Progression from HIV infection to AIDS is often accompanied or even predicted by a switch of the virus to a more pathogenic or syncytia-inducing (SI) phenotype concomitant with the development of HIV variants escaping neutralizing antibodies., Objective: Here we studied the capacity of sera to neutralize autologous SI-HIV or the laboratory strain III(B) and compared these data to the viral load in HIV-1-infected patients., Methods: The SI phenotype of HIV was detected by co-cultivation of peripheral blood mononuclear cells (PBMCs) with MT2 cells in 112 patients stratified by their CD4 cell counts. Sera at dilutions of 1 : 15 and 1 : 75 were added to MT2 co-cultures with autologous PBMCs as well as with HIV-1/IIIB-infected H9 cells to study the inhibitory capacity. The p24 antigenemia was detected by enzyme-linked immunosorbent assay (ELISA) and the circulating HIV RNA was determined using the polymerase chain reaction (PCR)., Results: The SI virus was detected in PBMCs from 31/65 patients with < or = 200 CD4+ cells, 8/28 patients with 201-499 CD4+ cells, and 1/19 patients with > or = 500 CD4+ cells. Sera from 16/40 patients inhibited the autologous SI-HIV. In sera from patients with < or = 200 CD4+ cells, p24 antigen could be detected in 17/34 (50%) patients with non-syncytia-inducing (NSI) phenotype and in 7/19 (37%) patients carrying SI-HIV without serum inhibition. In contrast, all 12 sera with inhibitory activity to the autologous SI-HIV were negative for p24 antigen. A similar tendency was seen in patients with higher CD4+ T-cell counts. The mean load of circulating HIV RNA did not differ among groups of patients. Independently of their neutralizing activity to the autologous SI virus, the majority of sera were able to neutralize the laboratory HIV-1/III(B)., Conclusions: While most of the patients' sera neutralized the laboratory HIV-1/III(B) strain, only some sera were able to inhibit the autologous SI-HIV. In these cases, the detectable SI-HIV may still be controlled by the immune system in vivo, which is consistent with a low p24 antigenemia.

Immunization with short antigenic peptides represents a potential strategy to induce peptide-specific CTL in vivo. In this study, a synthetic vaccine consisting of an HIV-derived, HLA-A2.1-binding CTL epitope and a tetanus toxin-derived T helper epitope was evaluated for its capacity to induce peptide-specific CTL in humans. Thirteen volunteers were immunized and boosted twice with 100 micrograms of the CTL epitope plus 300 micrograms of the T helper peptide (p30). Peripheral blood mononuclear cells (PBMC) were regularly analysed for cytotoxic and proliferative responses before, between and after the immunizations, and the serum was tested for anti-peptide antibodies. No unequivocal induction of HIV peptide-specific CTL in any of the volunteers was observed. However, a wide pattern of mild and transient side reactions was observed, ranging from local redness at the injection site to generalized exanthema, myalgias, arthralgias and fever. The side-effects were related to the T helper epitope, as they were similar to the side-effects experienced after tetanus immunization, correlated to the magnitude of the p30-specific in vitro proliferative response, and occurred only if p30 was co-injected. No antibodies against the HIV-derived peptides nor against p30 were detectable in the serum after repeated immunizations. The data suggest that the CTL peptide, at the concentration used in this study, failed to induce a cytotoxic immune response in vivo, although the T helper peptide seems to be capable of restimulating the specific memory T cells.

CD4+ T cells can exert different effector functions, which are partly distinguishable by the secretion of different cytokines, namely by either IFN-gamma, IL-2 and lymphotoxins for Th1-like or IL-4, IL-5, IL-10 and IL-13 for Th2-like T cells. Th1-like T cells can exert cytotoxic functions, too. The cytokinetic phenotype of an activated T cell clone (TCC) is mainly influenced by the cytokinetic pattern of the microenvironment where it was activated. However, the interaction between certain adhesion molecules (i.e. CD28-CD80 and CD28-CD86) may also have an influence on the functionality of the reactive T cell. On the contrary, the requirements for the induction of CD4+ cytotoxic T cells (CD4+ CTLs) are not well understood. We have focused this review on studies investigating the development of CD4+ T cells with cytotoxic effector functions. In particular, we discuss here whether the type of antigen-presenting cells (APCs) and the distinct expression of important adhesion molecules like CD80 and CD86 may influence the generation of CD4+ CTLs. Among a large panel of APCs only dendritic cells and TCCs are able to induce cytotoxicity. The level of CD80, but not of CD86, present on the APCs appears to be crucial for the induction of CD4+ CTLs.

Penicillin G (Pen G) and other beta-lactam antibiotics frequently induce allergic reactions constituting typical examples of human immune responses to haptens. In fact, penicillins represent a unique set of haptens with outstanding structural variability on the basis of an identical protein-reactive beta-lactam containing backbone. Although both cellular and humoral responses are involved in drug-induced allergies, little is known about the T cell reactivity to penicillins. To understand which structural features determine antigenic specificity, we isolated a panel of MHC-restricted, Pen G-reactive T cell clones from different penicillin-allergic patients and tested them for their capacity to proliferate in the presence of other penicillin derivatives. We found that the antigenic epitope consists of both the amide-linked side chain, which is different in every member of the penicillin family, as well as the thiazolidine ring common to all penicillin derivatives. We also demonstrated the presence of two different types of penicillin-specific T cells, one dependent, and the other independent of antigen processing by autologous antigen-presenting cells. Our data strongly suggest that penicillins form part of the epitopes contacting the antigen receptors of T cells.

Delayed pressure urticaria (DPU) is a rare disease of unclear pathophysiology and difficult to treat. Its typical manifestations are reddish, not itching swellings on parts of the body previously exposed to pressure and mostly only appearing 3 to 6 hours later. About 50% of the patients have general symptoms like fever, nausea and arthralgies. We report the case of a 36-year-old man who has suffered from DPU for 7 years. The incidence, symptoms and therapy of DPU are summarized and discussed in a short review of the existing literature.

Background: The rapid administration of bee venom in cumulative doses exceeding the quantity contained in one bee sting is well tolerated by most of the patients during 3.5 h of ultra-rush bee venom immunotherapy (VIT). The mechanism of this tolerance is unknown., Objective: The aim of the study was to verify the hypothesis that either slow mediator depletion of mast cells or blockade of their surface receptor mechanisms by increasing doses of allergen might be the major mechanisms of tolerance induced by ultra-rush VIT., Methods: Nine bee venom allergic patients with a history of severe systemic reactions after a bee sting, positive skin tests and bee venom specific serum IgE antibodies were treated as follows: on the first day a cumulative dose of 111 micrograms was administered over 3.5 h under intensive care conditions. Further injections were given on day 7, day 21 and thereafter at 4 week intervals. Intradermal tests with codeine phosphate (non-specific mast cell degranulation) and bee venom were performed before the initiation of VIT and 30 min after the last injection on the same day as well as before the subsequent bee venom injections., Results: No significant changes of skin reactivity to both codeine phosphate and bee venom were observed on day 1 (before initiation of VIT and after the last injection on the same day)., Conclusions: Ultra-rush VIT does not induce mediator depletion or surface receptor blockade in skin mast cells.

Aim: The study was designed to characterise more exactly the complex syndrome of exercise-induced urticaria and anaphylaxis in order to obtain guidelines for their management., Methods: 30 patients (18 women and 12 men with physical exercise-induced urticaria and anaphylaxis were investigated by questionnaire. The following items were of particular interest: age and sex; age at first manifestation; type, duration and intensity of the precipitating activity; type, duration and sequence of symptoms; prophylactic or therapeutic measures as cofactors., Results: Initial symptoms occurred at an average age of 22 (7-50) years. Atopy was present in 70%. Jogging (60%), ball games (40%) and walking (27%) were the most frequent precipitating activities. On each occasion symptoms began a few minutes to hours after the start of the exercise. During a typical episode an average of eight symptoms were observed, most frequently affecting the skin (pruritus, angiooedema, erythema and urticaria), dyspnoea and gastrointestinal manifestations. Syncope occurred in nine patients: before they lost consciousness they noted at least two prodromal symptoms. The most common co-factors were humid-warm weather, severe sweating and eating certain foods shortly before the exercise. Prophylactic measures were quite different between individuals., Conclusion: Providing detailed information on how to avoid possible cofactors and manage prodromal symptoms should be at the forefront of looking after such patients, most of whom lead a rather active life.

Activated T-cells expressing MHC class II surface antigens are able to present antigen and thus function as peptide-presenting cells (T-APCs). In this study we investigated whether antigen presentation by T-cells induced programmed cell death. As a model we used tetanus p30 peptide (aa 947-967)-specific, noncytotoxic CD4+ T-cell clones (C11 and C31). For experimental purposes these T-cell clones were stimulated (a) with p30 peptide-pulsed and fixed EBV-transformed antigen-presenting cells (B-APCs), (b) with p30-pulsed and fixed activated T-cells as APCs (as T-APCs we used either the T-cell clones themselves or an autologous T-cell clone (CT3) with p30 unrelated specificity), or (c) with soluble p30 peptide. The efficiency of antigen presentation was monitored by measuring proliferation as [3H]thymidine uptake. Apoptosis was measured by quantifying fragmented, cytoplasm DNA with the fluorescent dye 4,6-diamidino-2-phenylindole or by visualizing fragmented DNA by gel electrophoresis. Stimulation with p30-pulsed and fixed B-APCs or T-APCs induced proliferation but no apoptosis of the responding T-cells. However, stimulation of cloned T-cells with soluble peptide induced up-regulation of the FAS surface molecules and apoptosis, which was dependent on the peptide doses. Because cloned T-cells express HLA class II molecules, they can theoretically exert both functions at once: antigen presentation and antigen response when they are stimulated with soluble peptide. Because death by apoptosis is only seen under such circumstances, we suggest that T-cells simultaneously presenting and responding to an antigen die of apoptosis and thus contribute to the down-regulation of the immune response. Such phenomena might occur in HIV infection when activated CD4+ T-cells take up gp120 via their CD4 molecules, present it on their HLA class II surface antigens, and are simultaneously stimulated via their TCR.

Genetic differences in HLA phenotypes were studied in coeliac disease to investigate why some patients do not react with mucosal damage after gluten challenge. Forty five children with coeliac disease and 16 with transitory gluten intolerance were typed; 76 subjects served as controls. HLA phenotypes in children with coeliac disease had significantly higher proportions of DR3/X and DR5/7 than controls (48.8% v 11.8% and 26.7% v 5.3%). Children with transitory gluten intolerance had lower DR3/X (43.8%) than children with coeliac disease and there were no DR5/7 phenotypes. Further analysis of similarly well defined cases might show whether genetic differences in the DR3/X and DR5/7 phenotypes can serve as a marker for the permanence of gluten intolerance.

T cells recognize peptides in association with major histocompatibility complex (MHC) molecules on the surface of antigen-presenting cells (APC). To sensitize APC for antigen presentation in vitro and in vivo, high concentrations of synthetic peptides can be added from the outside and bind to the MHC molecules, thereby mimicking naturally processed peptides. In this report we investigated whether the transferrin (Tf) molecule could be used as a carrier to introduce antigenic peptides into the antigen presentation pathway of APC. We coupled to Tf various MHC class II DR1 restricted peptides and compared the sensitization of DR1+ APC by the Tf-bound or by the soluble peptide, using peptide-specific T cell clones (TCC). The presentation of the Tf-bound peptides was MHC restricted and could be blocked by the fixation of the APC with glutaraldehyde or by the addition of an excess of Tf. Tf-bound peptides were more efficiently presented than soluble peptides, since smaller concentrations were required to sensitize APC. Moreover, they could compete with a soluble peptide for MHC restricted presentation with a very high efficiency if compared to soluble competing peptides. Tf peptide conjugates could even compete with the presentation of a native antigen like tetanus toxoid. Peptides bound to the transferrin molecule might be useful for immunization strategies, as the relevant bound peptides are efficiently presented to peptide-specific TCC.

Human T cells express major histocompatibility complex (MHC) class II antigens and adhesion molecules characteristic of antigen-presenting cells (APCs), and recent in vitro and in vivo evidence supports an antigen-presenting function for T cells. In this guise, T cells provide downregulatory signals for the immune response by inducing anergy in T cells that have already been activated and cytotoxicity in resting T cells. Here, Werner Pichler and Tony Wyss-Coray suggest that this may represent an important negative mechanism for T-cell homeostasis.

To simplify the screening of monoclonal antibodies to different human T cell surface molecules a live cell enzyme-linked immunosorbent assay (cell ELISA) has been established and optimized. The assay was performed in 96-well plates. By using living human T lymphocytes in suspension surface modification by fixation or insolubilization of the cells was avoided. Several parameters influencing sensitivity and specificity were studied. About 150 ng/ml of mouse monoclonal antibodies to cell surface antigens could be detected when using 5 x 10(4) cells per well and a 1/1000 dilution of the anti-mouse IgG-alkaline phosphatase conjugate. This sensitivity permitted the primary screening of cell specific antibodies from hybridoma supernatants. The same detection limit was obtained in flow cytometric analysis. If required, the sensitivity of the cell ELISA could be increased using higher cell numbers and conjugate concentration. When analysing different cell lines with selected antibodies the cell ELISA was found to be as sensitive and specific as the fluorescence assay. The assay was applied to the screening of supernatants from hybridomas developed against human T helper cell clones and the detection of V beta specificities of T cell clones.

CD4+ T cell clones were generated to tetanus toxin or to two tetanus toxin-derived peptides p2 (AA 830-834) and p30 (AA 947-976). 11 of the 24 p30-specific clones reacted to shorter p30 subunits (p301 or p302), and only 14 of the p2 or p30-specific clones reacted with TT presented by EBV-transformed B cell lines (B-LCL). The p30-specific clones were HLA-DP4 restricted. In contrast to autologous B cell lines, the majority of allogeneic, but HLA-DP4-positive cell lines failed to present p30 to the specific clones. We concluded that T cell clones are highly specific and that both, small alterations of the peptide length as well as discrete differences of the HLA-molecule may abrogate recognition of the peptide HLA complex by T cells. Moreover, use of peptides as stimulators of T cells may recruit and activate T cells which fail the "original" peptide, derived from normal antigen processing. Clones could usually be maintained in culture for 4-6 months, but with the help of freezing and thawing some clones are now available for over 2 years and still specific. Comparison of different autologous antigen-presenting cells, namely B-LCL and activated MHC class II-positive T cells revealed that not all clones were able to mount a proliferative response to peptide presentation by T cells, while all clones proliferated to B cells as APC. If stimulated with peptide and B-LCL, the clone proliferating to T cells as APC (so-called T responder clones) secreted a broad spectrum of cytokines (Th0-like) and were easier to maintain in culture. In contrast, clones which were unable to proliferate to peptide presentation, so-called T-nonresponder clones, showed a more restricted cytokine pattern and elevated or very low IL4/IFN gamma ratio upon antigen specific stimulation. However, all clones secreted at least small amounts of IL2, IL4, IFN gamma and TNF alpha, if stimulated by PMA and ionomycin. Thus, both chemical and antigen-specific stimulations should be considered if T cell clones are classified as Th1 or Th2, whereby those clones, which secrete a limited cytokine pattern after antigen stimulation only, might be named Th1 or Th2 like clones, while clones which even after PMA/ionomycin do not secrete all cytokines, might represent "real" Th1 or Th2 clones.

Drug allergies can cause a great variety of symptoms and can thus imitate various diseases, like in previous times the lues. Drug allergies can be classified into three subgroups, which differ in their pathophysiology and require different diagnostic steps: firstly, classical drug allergies which are directed to the drug itself, a reactive compound of it or some contamination of the drug; secondly, pseudoallergic reactions which are caused by nonimmune mediated degranulation of mast cells and basophils; and thirdly, autoimmune reactions in which the drug elicits an immune reaction to autologous structures. A very detailed (criminalistic) history has the highest priority for the clarification of a suspected drug-allergic reaction; in addition, skin tests, serological tests and the lymphocyte transformation test might be useful. One should differentiate between tests which imitate the drug-elicited allergic reaction (i.e. Coombs test in drug induced hemolytic anemia) and tests which solely indicate a sensitization, these tests should be interpreted accordingly.

Antigenic peptides derived from endogenous or viral proteins can associate with class I or class II major histocompatibility complex (MHC) molecules, while exogenous antigens are endocytosed, processed intracellularly and presented on MHC class II molecules. Here we describe a method that allows the presentation of an MHC class I-restricted antigenic peptide on MHC class I molecules, although it was taken up from the outside. The HLA-A2-restricted influenza virus matrix protein-derived peptide (flu, 57-68) was used either in soluble form or coupled via an S-S bridge to transferrin (Tf-flu). Target cells were incubated with flu or Tf-flu and the effective antigen presentation was detected in a cytotoxicity assay using flu peptide-specific, HLA-A2-restricted CD8+ cytotoxic T lymphocytes. Sensitization of target cells with Tf-flu required 5 to 10 times higher molar concentrations of peptide compared to sensitization with soluble free peptide. The Tf-flu construct was taken up by the cells via the Tf receptor (CD71) as the binding of Tf-flu was blocked by an excess of Tf. In contrast to the flu peptide, cytotoxicity elicited by Tf-flu was blocked by brefeldin A but not by chloroquine nor inhibitors of intracellular reducing steps, like 1-buthionine-(s,r)-sulfoximine or n-ethylmaleimide. Presentation of the flu peptide derived from Tf-flu construct is not hindered in the mutant T2 cell line, which lacks genes coding for transporter proteins for antigenic peptides (TAP1/TAP2) and proteasomes subunits, suggesting that the processing pathway described in this report may involve TAP-independent steps.

One of the factors that may influence the cytokine secretion profile of a T cell is the antigen-presenting cell (APC). Since activated human T cells have been described to express major histocompatibility complex (MHC) class II molecules as well as costimulatory molecules for T cell activation, like e.g. ICAM-1, LFA-3 and B7, they might play a role as APC and be involved in the regulation of T-Tcell interactions. To define further the role of T cells as APC we tested their capacity to induce proliferation and cytokine production in peptide- or allospecific T cell clones and compared it with conventional APC, like B lymphoblasts (B-LCL) or HTLV-1-transformed T cells, or with non-classical APC, like activated keratinocytes or eosinophils. CD4+, DP-restricted T cell clones specific for a tetanus toxin peptide (amino acids 947-967) and CD4+, DR-restricted allospecific T cell clones produced interleukin (IL)-2, IL-4, tumor necrosis factor-alpha and interferon-gamma (IFN-gamma) after phorbol 12-myristate 13-acetate and ionomycin stimulation and a more restricted cytokine pattern after antigen stimulation. Dose-response curves revealed that the antigen-presenting capacity of activated, MHC class II+, B7+ T cells was comparable to the one of B-LCL. Both APC induced the same cytokine profile in the T cell clones despite a weaker proliferative response with T cells as APC. Suboptimal stimulations resulted in a lower IFN-gamma/IL-4 ratio. Cytokine-treated, MHC class II+ keratinocytes and eosinophils differed in the expression of adhesion molecules and their capacity to restimulate T cell clones. The strongly ICAM-1-positive keratinocytes induced rather high cytokine levels. In contrast, eosinophils, which express only low densities of MHC class II and no or only low levels of adhesion molecules (B7, ICAM-1 and LFA3), provided a reduced signal resulting in a diminished IFN-gamma/IL-4 ratio. We conclude that non-classical APC differ in their capacity to restimulate T cell clones, whereby the intensity of MHC class II and adhesion molecules (B7, ICAM-1) expressed seems to determine the efficacy of this presentation.

The B cell antigen B7 delivers a strong co-stimulatory signal for the activation of T cells by binding to its ligands CD28 and CTLA4. Here we demonstrate the surface expression of the B7 molecule on activated human T cells in vitro and under certain conditions in vivo and its functional importance in T-T cell interactions. B7 was detected by flow cytometry on antigen-specific CD4+ and allospecific CD8+ cloned T cells from different donors with anti-B7 monoclonal antibody (mAb) or a soluble CTLA4-C gamma 1 chimera molecule and by reverse transcription-polymerase chain reactions. The expression of B7 was up-regulated following restimulation of the T cell clones and peaked after 7-9 days. Moreover, we show that the B7 molecule on T cells is functionally involved in T-T cell interactions: mAb to CD28 and the CTLA4-Ig fusion protein could inhibit the proliferation of specific T cell clones in response to T cells as antigen-presenting cells (APC) or the proliferation of peripheral blood mononuclear cells in a primary allostimulation with activated T cells as stimulator cells. Finally, we found that B7 can be expressed on freshly isolated circulating T cells since in a preliminary study with a limited number of patients, B7 was present on a subset of CD3+ cells. B7 was expressed on activated T cells (CD4+ and CD8+) of certain human immunodeficiency virus (HIV)-infected individuals (0.5-20% B7+CD8+ cells) or some patients with autoimmune diseases whereas CD3+ cells of healthy individuals did not express B7. The coexpression of major histocompatibility complex class II molecules and B7 may be relevant for the capacity of activated T cells to function as APC. The expression of B7 on T cells in vivo in autoimmune diseases and in HIV infection may be important for a better understanding of these diseases.

Drug allergies can be subclassified into three subgroups, which differ in their pathophysiology and require different diagnostic steps: (1.) classical drug allergies, which are directed to the drug itself, a reactive compound of the drug, or some contamination of it; (2.) pseudo-allergic reactions, which are caused by non-immune mediated degranulation of mast cells and basophils, and (3.) autoimmune reactions, in which the drug elicits an immune reaction to autologous structures. A very detailed (criminalistic) history has the highest priority for clarification of a suspected drug allergy. In addition, skin tests, serological tests and the lymphocyte transformation test may be useful. It is necessary to differentiate between tests which imitate the drug elicited allergic reaction (i.e. Coombs test in drug induced hemolytic anemia) and tests which only indicate sensitization. The detection of IgG antibodies to drugs bound to various carriers (nitrocellulose, sepharose) is controversial and the meaning of a positive result is unclear. Therefore, this test cannot be recommended for the routine diagnosis of drug allergy. Special emphasis is placed on the value of the lymphocyte transformation test, which is more often positive than other test procedures and may sometimes strengthen the suspicion that a disease may be caused by a drug. Nevertheless, this test requires cautious interpretation as it may be falsely positive as well as falsely negative.

Drug allergies can be classified into three subgroups which differ in their pathophysiology and require different diagnostic steps: 1. classical drug allergies, which are directed against the drug itself, a reactive metabolite or some contaminant of the drug, 2. pseudoallergic reactions, which are caused by non-immune mediated degranulation of mast cells and basophils, and 3. autoimmune reactions, in which the drug elicits an immune reaction to autologous structures. A very detailed accurate history is of the greatest importance in the clarification of a suspected drug allergic reaction, as well as experience with the drug. In addition, skin tests, serological tests and the lymphocyte transformation test may be useful. One should differentiate between tests which imitate the drug-elicited allergic reaction (i.e., Coombs test in drug-induced hemolytic anemia) and tests which solely indicate a sensitization and the tests must be interpreted accordingly.

Seven patients who received a lysozyme, nystatin, and tetracycline containing vaginal suppository because of suspected vaginal infection, developed local or systemic allergic reactions. The coincidence of the symptoms with the repeated use of the suppository as well as skin and lymphocyte transformation tests indicated that the lysozyme in the suppository was responsible for the allergic reactions. This lysozyme preparation contained additional egg proteins, which contributed to the allergic reaction in certain patients: three patients with a previous history of egg allergy and serologic and/or skin test evidence for egg-white sensitization developed the allergic reaction after the first suppository. Four patients had urticaria or anaphylaxis after treatment for at least three days; none of these four patients developed egg allergy. Five of seven individuals had positive skin tests (prick or scratch) to ovomucoid and lysozyme, but none of the patients had lysozyme-specific IgE in the circulation. All seven patients, with or without egg allergy, showed vigorous T cell responses to purified lysozyme and partly to other egg-white proteins in the lymphocyte transformation test, which was absent in controls. Vaginal suppositories that contain lysozyme and other contaminating egg white proteins can either elicit allergic reactions in patients with a preexisting egg white allergy or induce sensitization to lysozyme and other egg white components.

In this report, we describe the discrimination of human T cell clones based on their reactivity with activated T cells as antigen-presenting cells (APC). CD4+ T cell clones specific for peptide P30 of tetanus toxin (amino acids 947-967) and restricted to the DP4 molecule were established and tested for proliferation to peptide presented either by peripheral blood mononuclear cells (PBMC), Epstein-Barr virus (EBV)-transformed B cells or major histocompatibility complex (MHC) class II-expressing T cells. We found two sets of T cell clones: one set proliferated to peptide presentation by PBMC, EBV-transformed B cell lines (EBV-B cells) and MHC class II+ T cells (termed T-responder clones), while the other set of clones was only stimulated to proliferate, if the peptide was presented by PBMC or EBV-B cells, but not by T cells (T-nonresponder clones). Nevertheless, these T-nonresponder clones recognized P30 also on T cells, as revealed by Ca2+ influx. The discrimination of the clones was not due to different avidities of the T cell receptors (TcR) of individual clones for the MHC-peptide complex as T-responder and T-nonresponder clones had similar dose-response curves to P30 presented by fixed EBV-B cell lines. Addition of cytokines [interleukin (IL)-1, IL-2, IL-4 and interferon gamma] did not change the proliferative response of the clones, which was consistent throughout an observation period of greater than 4 months. T-nonresponder clones, exposed to P30 on MHC class II-expressing T cells, became not anergic, as they could be restimulated by P30 presented on EBV-B cells. The measurement of a panel of T cell activation markers and adhesion molecules on T-responder and T-nonresponder clones revealed a higher expression of the CD28 molecule on the T-nonresponder clones. The data suggest that freshly cloned T cells can be differentiated by peptide presentation on classical (PBMC, EBV-B cells) or non-classical APC (class II+ T cells), and that this discrimination is further underlined by different levels of adhesion molecules.

Human T cells can express MHC-class II products and were shown to be potential antigen-presenting cells. However, they are unable to capture the antigen and only antigens, which bind to T cell membranes such as the gp120 glycoprotein of HIV, are internalized, processed, and presented by T cells. To better understand the role of T cells as antigen-presenting cells, we established a method which overcomes the lack of antigen capture by T cells. Antigen (tetanus toxoid, TT) or an antigenic peptide of TT (residue 830-843, P2) was coupled to antibodies directed to T cell surface molecules such as CD2, CD4, CD8. Antibody/TT and antibody/P2 constructs stimulated P2-specific T cell clones in the absence of accessory cells, if the antibody recognized a T cell surface structure. Compared to the peptide alone, a 100-500 times lower molar concentration of the antibody/peptide construct was required to achieve a similar proliferative response. T cell stimulation via the constructs involved intracellular processing, as nonspecific, glutaraldehyde fixed T cell lines pulsed with the constructs could present the peptide and processing inhibitors like Leupeptin or Chloroquine inhibited the development of a proliferative response to the constructs. Our data underline the ability of T cells to function as antigen-processing and -presenting cells and show that antibody/antigen or antibody/peptide constructs are able to direct a certain antigen or peptide to a T cell. Antibody/peptide constructs may be interesting tools to better understand antigen processing and to study the consequences of antigen presentation by different cells.

Chemiluminescent detection of polymerase chain reaction (PCR-)amplified DNA was used as a quantitative method for detecting HIV-1. For this purpose, biotinylated dUMP was directly incorporated into the amplified DNA during the PCR reaction. Biotinylation was visualized in an enzymatic reaction using avidine-conjugated alkaline phosphatase and its chemiluminescent 1,2-dioxetane substrate AMPPD, which decomposes upon dephosphorylation and emits light. Light emission was either detected with X-ray films or quantified with a single-photon counting camera connected to a computer imaging system. The specificity of the method was shown by hybridization with a biotinylated or radiolabelled HIV-1-specific oligonucleotide probe. Besides being quantitative, this method represented a non-hazardous, rapid and sensitive technique for the detection of HIV-1 DNA.

To analyze the proliferative capacity of CD4+ or CD8+ T-cell subsets of individuals infected with human immunodeficiency virus type 1 (HIV-1) and to optimize the in vitro conditions for virus replication, CD4+ or CD8+ cells of HIV-1-infected patients were selectively activated inside the whole peripheral blood mononuclear cell (PMNC) population by dual antibody stimulation. To do so PMNC of HIV-1-infected individuals were stimulated with the per se nonmitogenic anti-CD3 antibody fragment BMA030 F(ab)2 crosslinked through goat antimouse antibodies with an anti-CD4 or an anti-CD8 antibody, which lead to selective proliferation of either the CD4+ or the CD8+ T-cell subset. In the presence of monocyte supernatant and recombinant interleukin-2 (rIL2) CD4+ cells of HIV-1 patients responded normally upon such stimulation as their proliferation correlated (r = 0.9) to the percentage CD4+ cells present in the PMNC population. Selective stimulation and proliferation of CD8+ cells could, however, only partially be elicited by dual antibody stimulation, even in the presence of rIL-2 and monocyte supernatant. Their proliferative response did not correspond (r = 0.1) to the percentage CD8+ cells present in the PMNC culture. A positive correlation (r = 0.7) was detected only between percentage CD8+ HLA-DR- cells and proliferation. This confirmed previous studies showing that the defective in vitro proliferative response of peripheral blood lymphocytes of HIV-infected individuals to mitogens, which is usually interpreted being due to a CD4 cell defect, is actually due to a failure of CD8+DR+ cells to proliferate.(ABSTRACT TRUNCATED AT 250 WORDS)

HIV predominantly infects the CD4+ T cells, which during the progression of the disease are eliminated, causing an immune deficiency which renders the patients more susceptible to infections. To evaluate the relevance of the CD4+ T cell elimination and thus the clinical usefulness of CD4/CD8 subset determinations in HIV infected persons, we investigated whether analyses of 667 subset determinations of 365 patients correlated with clinical stages of HIV-infection (CDC classification). Progress of HIV related disease was accompanied by a fall in CD4+ cells and an increase in CD8+ cells, leading to a drastically reduced CD4/CD8 ratio. This change of T-cell subset values correlated well with the clinical classification (CDC). It was, however, only statistically significant if percent values were used, but not if absolute CD4 cell counts, calculated from the peripheral lymphocyte count, were considered. While patients in CDC stage IVC2 (mainly Candida stomatitis) did not differ from stages IIB, IIIB, IVA, we found statistically lower CD4 values if the patients had stage IVA plus IVC2. Stage IVC1 (mainly Pneumocystis carinii pneumonia [PcP, n = 20]) had even lower CD4 values, as PcP appeared almost exclusively in patients with CD4 counts below 20% or 200/microliter. The lowest CD4 counts were observed in patients with Kaposi sarcoma (n = 11) with CD4 cells less than 10% and significant elevated values of CD8 cells (greater than 50%). While the total lymphocyte count correlated with the absolute counts of CD4 and CD8 cells, it was impossible to estimate the T-subset distribution from the absolute lymphocyte count. Our investigations show that a decreased number of circulating CD4 cells correlates well with an increased tendency to develop infections, and thus support the relevance of CD4 cell measurements for the optimal care of asymptomatic HIV infected persons in particular. They also show that the percent values correlate better with clinical stage than the absolute CD4 cell count.

Bacterial extracts are offered as immunostimulatory drugs for the treatment of recurrent infections. A critical review of their postulated immunological efficacy shows that (a) the postulated immunostimulatory efficacy relies mainly on irrelevant in vitro data; (b) the data are inconsistent and contradictory; (c) the immunological efficacy of bacterial extracts given by mouth is doubtful. In addition to the missing immunological basis, various clinical studies have likewise failed to provide a convincing result. The main argument against the use of bacterial extracts as immunostimulants is, however, a wrong indication, as most patients with recurrent infections do not have an immune deficiency but suffer from recurrent infections because of a damaged barrier function (i.e. altered composition of mucus). In spite of these limitations the use of bacterial extracts as "immunostimulants" can be justified, as side effects are very rare, therapy with an "immunostimulant" is attractive for the patient, and the use of antibiotics might be reduced.

Monoclonal antibodies against the TCR/CD3 complex are capable of activating T cells which in turn may induce immunoglobulin synthesis in B cells under appropriate conditions. Here we present evidence that distinct immune responses, induced by four commonly used TCR/CD3 mAb (Leu4, OKT3, BMA030, BMA031) were related to the mAb interaction with monocyte Fc receptors for IgG. Depending on their isotype and on the technique by which they were crosslinked, TCR/CD3 mAb induced variable IgM and IgG synthesis in PBMC: If the mAb were crosslinked by monocyte IgG-Fc receptors they induced a high Ig production, while crosslinking the same mAb by plastic-bound goat anti-mouse antibodies (panning) failed to do so. Nevertheless, both crosslinking techniques triggered a strong proliferation and IL-2, IL-4, and IFN gamma lymphokine gene expression. The lack of Ig production under panning conditions was due to an additional IgG-Fc receptor interaction with monocytes: (a) If namely mAb F(ab')2 fragments, or mAb isotypes unable to bind to monocyte Fc receptors (IgG2b, IgG1 in nonresponders) were crosslinked by panning, both a good proliferation as well as Ig production ensued; (b) if TCR/CD3 mAb isotypes which could additionally bind to monocyte Fc receptor (IgG2a) were crosslinked, no Ig production occurred; (c) if mAb F(ab')2 fragments were crosslinked with a second anti-T cell antibody of IgG2a isotype, which could bind to monocyte Fc receptors, Ig synthesis was reduced. Interestingly enough, this diminishing effect, due to monocyte Fc receptor interaction, was only observed if CD4-positive cells were proliferating, but not if CD8-positive cells were activated.

Using the model of dual antibody stimulation (cross-linking anti-CD3 BMA030-F(ab')2 antibodies with subset specific anti-T cell antibodies, i.e., anti-CD4 or anti-CD8 antibodies) we investigated the role of monocyte products in eliciting IL2 production and asked whether T cell subsets differ in their activation requirements. We found that activation mechanisms of dual antibody stimulation were equal for CD4 and CD8 as well as CD4 CDw29 and CD4 CD45R T cell subsets: dual antibody stimulation was necessary to induce responsiveness to soluble monocyte products which trigger IL2 synthesis. IL2 production induced by soluble monocyte products was measured in CD4 and CD8 T cells as specific IL2 mRNA expression and with a biological assay. Combined actions of IL1 beta and TNF alpha were identified as active monocyte products as (a) treatment of LPS-stimulated monocyte supernatants with anti-IL1 beta and anti-TNF alpha antibodies abrogated the proliferation inducing effect of monocyte supernatants and (b) addition of rIL1 beta and/or rTNF alpha enhanced proliferation of T cells stimulated by dual antibody cross-linking. If both recombinant monokines were added simultaneously a potentiated proliferative effect was observed. Whereas rIL1 beta plus/or rTNF alpha sustained proliferation, only rIL1 beta but not rTNF alpha induced IL2 synthesis in T cell subsets stimulated by dual antibody cross-linking.

To evaluate the functional significance of the T-cell membrane structure recognized by OKT8 or Leu2a, seven different monoclonal antibodies, reacting with different epitopes of this 76 KD big membrane structure, were evaluated for their ability to alter specific cell mediated lympholysis after a mixed leukocyte reaction. The stimulated effector cells were first incubated with a monoclonal antibody, washed and then tested for their cytotoxicity. Those antibodies, which react with a highly trypsin-sensitive region of the T8 glycoprotein, were the most effective inhibitors of the cytotoxicity (T811, FK18). Those antibodies, which react with a relative trypsin-resistant region (OKT8, Leu2a, WT82, WT85) or with a trypsin-sensitive epitope (WT81), which is in a close neighborhood to WT82 or WT85, appear to be able to block the cytotoxicity only in certain effector/target cell combinations. The data suggest that different regions of the T8 glycoprotein are involved in the specific cytotoxic reactions, and that the involvement of certain epitopes may depend on the effector/target cell combination.

The syndrome of exercise induced anaphylaxis represents a distinct form of physical allergy. This syndrome and the features which distinguish it from other forms of physical allergy are discussed in the context of 10 case reports. The symptoms usually start after 5-30 minutes' exercise with cutaneous pruritus, warmth and progress to urticaria and angioedema. In 3 cases signs of laryngeal edema were present; additional manifestations included upper respiratory distress, gastrointestinal tract symptoms and collapse. The syndrome is distinct from exercise induced asthma or cholinergic urticaria. One patient had both cholinergic urticaria induced by stress, heat and exercise, and anaphylactoid symptoms induced by exercise alone. While the symptoms of cholinergic urticaria subsided after 2-4 hours, the anaphylactoid symptoms lasted up to 48 hours. The symptoms are elicited irregularly, which suggests a multifactorial trigger mechanism. The intake of particular foods or acetylsalicylic acid, and certain weather conditions, are possible cofactors. In 8 of 10 patients an atopic diathesis was found but no exposition to a specific allergen, which could explain the symptoms, was observed. Therapy consists of avoidance of cofactors, change of training habits and cessation of exercise as soon as prodromal symptoms develop. If attacks are frequent, antihistamines or ketotifen can be tried. The acute attack should, like other anaphylactoid reactions, be treated by antihistamines, injection of epinephrine (s.c.) and infusions (colloidal solutions).

Cells from different fetal and adult lymphoid organs were tested for the capacity to (a) react to the T-cell growth factor interleukin-2 (IL-2) and (b) to produce IL-2 under appropriate conditions. IL-2 was determined as growth promoting activity for mouse T blasts. Optimal conditions for IL-2 production were: 5 X 10(6) cells/ml; 4-6 micrograms mitogen, 24 h incubation time. Concanavalin A was preferable for fetal thymus, whereas phytohemagglutinin was the appropriate mitogen for lymphocytes from blood and lymph node. Fetal and adult spleen cells produced equal activities of IL-2 irrespective of the mitogen used. Cells from thymus and spleen of 17-21-week-old fetuses produced IL-2 activities like adult cells. Fetal liver cells from the same fetuses produced no IL-2. A comparison of IL-2 activities released from cells of 26 donors showed that within individual variations there was no decrease of the capacity to produce IL-2 with old age. An activity present in culture media of mitogen treated lymphocytes which increased thymidine uptake in fetal liver cells could be distinguished from IL-2 by its different molecular weight and by a heat treatment which abolished IL-2 but not fetal liver cell growth promoting activity. This latter activity is discussed to be colony-stimulating activity. It is concluded that IL-2 is produced by and reacts with T cells only after they have reached or passed the thymus.

Various tests to determine the cellular immune response in HIV infected persons are presented and their use in clinical practice is discussed. The T4 cell count using the full blood method is a precise test for evaluation of T4 cell elimination by HIV infection and the immune deficiency thus developing. The skin test to various recall antigens (multitest) is simple and helpful in confirming a suspected immune defect. It is, however, too insensitive to detect incipient T4 cell destruction without functional consequences. The lymphocyte count is diminished in final disease stages only and is not helpful in discriminating between early disease stages. Proliferative tests of isolated lymphocytes are of prognostic relevance if antigen is used as a stimulus, since diminution of antigen induced proliferation is a sensitive parameter of immune dysfunction. The value of mitogen induced proliferations lies in possible comparison of the effect of autologous or control serum on proliferative response, since immunosuppressive factors may be found in sera of HIV infected persons.