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Summary Dendritic cells (DC) modulate immune responses depending on the nature of the antigens. Receptors capable of discriminating these antigens on the basis of the pathogen-associated molecular patterns (PAMP) belong to the Toll-like receptor (TLR) family. The macrophage-activating lipopeptide 2 kDa (MALP-2), a synthetic lipopeptide derived from Mycoplasma fermentans , signals through TLR-2 and TLR-6. The aim of this study was to examine whether MALP-2 can modulate the functional properties of human monocyte-derived DC. The effects of this treatment were compared to those of the TLR-4 agonist lipopolysaccharide (LPS). To ensure clinical applicability, DC were generated under serum-free conditions. MALP-2 and LPS stimulation induced the expression of CD83 and increased the expressions of CD80, CD86, HLA-ABC and CD40. Furthermore, both substances decreased the endocytotic capacity of DC and induced the release of bioactive TNF-α and IL-10, whereas LPS additionally increased IL-12 release. Pretreatment with both substances boosted the allostimulatory capacity of DC. In a coculture with autologous lymphocytes, either MALP-2 or LPS pretreated DC induced a marked proliferation of lymphocytes, but only DC prestimulated with MALP-2 activated lymphocytes to produce the cytokines IL-4, IL-5 and IFN-γ. No polarisation of lymphocytes into T-helper (Th)1 or Th2 was detected. These data indicate that MALP-2 is a potential candidate to modulate DC for clinical applications.

Herein, we report a technically simple method for isolation and culture of human follicular melanocytes based on explant cultures of epilated hair follicles. This technique does not require any surgical intervention and allows the isolation and cultivation of follicular melanocytes from a comparatively small amount of raw material. Generally, 30-60 human anagen hair follicles have been plucked from the scalp of healthy donors and cultivated under low oxygen pressure (5%). After a short period of time cells of various types were growing out from the outer root sheath (ORS) of the hair follicles. Under the selected culture conditions, most of the cells other than melanocytes have been eliminated and a nearly 100% pure population of melanocytes has been achieved, as confirmed by immunohistochemical analyses for melanocyte-specific markers, for example, Tyrosinase-1, S-100 and premelanosomal antigens. These melanocytes derived from the ORS were proliferating for up to 2 months.

The effects of normal bone marrow fibroblasts (BM FB) on proliferation and differentiation of 10 myeloid leukemic cell lines were investigated in a serum-free co-culture system. The proliferation of three of the cell lines was supported by BM FB. Three of the myeloid cell lines were inhibited 40-70%. The co-culture supernatants were tested for the secretion of hematopoietic cytokines by bioassays. Except for IL-6, which was already produced constitutively by BM FB, only little amounts of interleukin-1 (IL-1), granulocyte colony-stimulating factor (G-CSF), or granulocyte-macrophage colony-stimulating factor (GM-CSF) could be detected in several co-culture supernatants. It could be shown that, according to cytologic and functional criteria, the myeloid leukemic cell lines ML-2 and PLB-985 differentiate along the monocyte-macrophage pathway after co-culture with BM FB. They revealed a histiocytic phenotype and could be induced to produce reactive oxygen intermediates (ROI) after stimulation with zymosan or phorbol-myristate-acetate (PMA). Additional proof for differentiation was obtained from flow cytometric analysis of surface differentiation antigens and adhesion molecules. The neutralization of IL-6 activity in the co-cultures by antibodies resulted in prevention of differentiation of PLB-985 cells, while differentiation of ML-2 cells in the co-cultures was not affected by addition of anti-IL-6 antibodies. Furthermore, in co-culture experiments with fibroblasts from skin and foreskin, we found a differentiation of PLB-985 cells comparable to that in co-cultures with BM FB, but poor differentiation of ML-2 cells. These data suggest that different mechanisms are involved in the differentiation of ML-2 and PLB-985 cells.

Listeria monocytogenes is a bacterial infection, which is facultatively localized in monocytes and macrophages. The influence of ibuprofen (CAS 15687-27-1), a nonsteroidal anti-inflammatory drug (NSAID), on this bacterial infection in balb/c mice was investigated. One day prior to sublethal infection, balb/c mice were treated intravenously with various therapeutic concentrations of ibuprofen alone or ibuprofen in combination with a suboptimal dosage of murine recombinant interferon gamma, a lymphokine produced by T-helper cells. Three days post-infection, parasite burdens of the mainly infected organs, spleen and liver, were determined by the colony-forming unit assay. It was shown that the prophylactic treatment with ibuprofen in a concentration of 4 mg/kg body weight resulted in a more than 10-fold reduction of viable Listeria monocytogenes in the spleen, whereas in liver 12 mg/kg Ibuprofen was necessary for a comparable kill of viable bacteria. A higher concentration of ibuprofen did not resulted in a higher antibacterial efficacy. In order to clarify the mechanism of ibuprofen action, molecular-biological experiments were performed to measure the messenger RNA (mRNA) induced by ibuprofen. It is presented here that therapeutic concentrations of ibuprofen induced significant higher amounts of mRNA for interleukin-1 in human monocytes compared to untreated cells. These findings support the hypothesis that ibuprofen influences the complex immune system to overcome a bacterial infection.

Neutrophils from 50 pediatric patients with normal phagocyte functions, from 150 healthy adults, from 10 chronic granulomatous disease (CGD)-patients (4 CGD+), and from 18 X-linked carriers for CGD have been tested for their production of H2O2 using staining with dihydrorhodamine 123 and subsequent flow cytometry. Additionally, neutrophils from three patients with myeloperoxidase deficiency were assessed. Cells were activated to produce H2O2 by the phorbol ester phorbol-myristate-acetate (PMA) and by phagocytosis of Escherichia coli bacteria. To evaluate the sensitivity of the method, H2O2-production by neutrophils which was inhibited by different concentrations of diphenyljodonium (DPI) was measured. The results were compared to those from other methods (NBT-testing, cytochrome c-reduction, and especially chemiluminescence). Normal values and ranges of scatter profile were evaluated in terms of peak channel fluorescence: 97%700, x = 840 +/- 59 (S.D.), 97%890, for pediatric patients. Normal quantitative values also resulted from small blood samples of infants (1 year, n = 6, x = 830 +/- 52). For CGD+ (n = 4) the results were clearly far below the normal range. In indicating decreased production of reactive oxygen intermediates the method was at least as sensitive as lucigenin enhanced chemiluminescence. Cytochrome b558-expression of neutrophils from patients and healthy controls was established by flow cytometry following staining with the monoclonal antibody 7D5. The normal range was 97%485, 97%680, peak channel fluorescence. We conclude that flow cytometric routine diagnostics of CGD can easily enhance the reliability of recognition and the yield of information about this disease compared to conventional methods.

Controversial results have been published on the immune response to cigarette smoking while the effects of exposure to environmental tobacco smoke (ETS) have not yet been reported. In a controlled study, acute effects of smoking and of a high environmental exposure to ETS on immunological parameters have been investigated. The study consisted of four experimental days, two control and two exposure days. On control days, 1 and 3, smokers (n = 5) and nonsmokers (n = 5) sat in an unventilated 45 m3 room for 8 h. On the exposure days, 2 and 4, each of the smokers smoked 24 cigarettes in 8 h, while the nonsmokers were exposed to the ETS generated by the smoking volunteers. Blood was drawn before and after each exposure session on all four experimental days for dosimetry of tobacco smoke exposure and determination of the immune response. Flow cytometry using monoclonal antibodies was used to determine CD3+ cells (whole T cells), CD19+ cells (B lymphocytes), CD16+ and CD56+ cells (natural killer cells), CD4+ cells (T-helper cells), CD8+ cells (T-suppressor cells), the CD4+/CD8+ (helper/suppressor ratio), and Fc receptors on granulocytes. Serum was analyzed for soluble CD14 receptors (sCD14), interleukin 1, interleukin 6 and prostaglandin E2 (PGE2). Functional stimulation assays were performed to determine the basal and induced level of reactive oxygen intermediate (ROI) production by polymorphic neutrophils. Exposure to tobacco smoke in both groups was confirmed by dosimetry of carboxyhemoglobin, plasma nicotine, and cotinine levels. In comparison to nonsmokers, smokers had elevated granulocyte cell counts, increased CD16+ and CD56+ cell levels and decreased CD3+ and CD19+ levels. Acute smoking, but not exposure to ETS, resulted in a slight decrease in the number of CD19+ cells and an increase in the number of granulocytes; the latter was restricted to one subject. Acute smoking and exposure to high experimental concentrations of ETS resulted in a slight increase in CD16+ and CD56+ cells. None of the changes determined in immunological parameters after either acute smoking or exposure to ETS reached statistical significance. Serum sCD14, cytokine and PGE2, functional stimulation of in vitro ROI production, and changes in Fc receptors were not affected by acute smoking or exposure to ETS. Although no clear guidelines exist to assess immunotoxicity in man, our data do not favor immunosuppression and the possibility of increased risk of infection in nonsmokers exposed to ETS under real-life conditions.

Recently, the diagnosis of a variant form of chronic granulomatous disease (CGD) could be established in an 11-year-old girl who had been treated for atopic dermatitis for many years. In addition to severe superinfections of lesions of the skin, the following symptoms were found currently or in her history: an episode of chronic diarrhoea (suspected as lactose intolerance), an endomyocarditis, a paranephritic abscess and recurrent lymph node abscesses. This case is demonstrated to underline the importance of extensive immunologic diagnostics in situations of recurrent severe infections of the skin, especially if other organs are involved. Diagnosis and type of CGD were strongly indicated by flow cytometrical measurement of H2O2 and cytochrome b558-expression by neutrophils and confirmed by a Western blot test. No immunoreactive p47phox could be found in the patient's cells. In this autosomal recessive variant of CGD some retained ability of phagocytes to produce reactive oxygen intermediates was present. Special management of patients with CGD is necessary to prevent serious infectious complications. Genetic counselling is another important consequence of the correct diagnosis.

Flow cytometric analyses were performed to study intracellular single-cell calcium transients ([Ca2+]i) in suspended human neutrophils during the initial phase of N-formyl peptide stimulation. Thereby, two neutrophil populations became apparent. Early maximally Ca(2+)-responding (high fluorescence) neutrophils and not-yet Ca(2+)-responding (low fluorescence) neutrophils, but no neutrophils with intermediate levels of [Ca2+]i were detected. Within 7 s the number of low fluorescence neutrophils decreased and the number of high fluorescence neutrophils increased maximally. This suggests that [Ca2+]i transients occurred abruptly in individual neutrophils within a time interval below 1 s. At lower N-formyl peptide concentrations the lag times of individual neutrophils and the interval time of maximal activation of the [Ca2+]i-responding neutrophil population increased, however the percentage of [Ca2+]i-responding cells decreased. Surprisingly, no influence of the N-formyl peptide concentration on the [Ca2+]i-induced fluorescence signal of the individual cell was observed: it was always in an almost maximal range or not responding. In parallel, binding studies performed with fluorescein-labeled N-formyl peptide revealed that the heterogeneity of [Ca2+]i-responding cells cannot be explained by different receptor occupancy. In summary, this study demonstrates that [Ca2+]i transients induced by N-formyl peptides in suspended individual human neutrophils occur very rapidly in an almost "all-or-none manner" and that the mean increasing fluorescence signal of a calcium indicator within a whole neutrophil population results from varying lag times of the individual cells, rather than from the mean simultaneous progress of many cells.

We have demonstrated that human fibroblasts can release O2-. radicals by an NADPH oxidase system that appears to be functionally similar to the phagocytic system. Further analysis of these systems, however, with respect to the low-potential b-type cytochromes involved suggests that these two O2-.-generating systems are not structurally identical. Immunoblot analysis of fibroblast membranes with six different antibodies directed against both subunits of human neutrophil cytochrome b-558 indicated that the b-type cytochrome molecules involved in these systems were not identical. None of these anti-(neutrophil cytochrome b) antibodies recognized a similar cytochrome in fibroblast membranes, suggesting that the two cytochrome species are immunologically distinct. In addition, fibroblasts obtained from a patient suffering from X-linked chronic granulomatous disease (CGD) had a normal cytochrome b-558 content compared with control fibroblast membranes, whereas the cytochrome b-558 concentration in polymorphonuclear leucocytes (PMNs) from this patient was decreased to 10% of that found in PMNs from healthy controls. Likewise, the stimulated O2-. release in PMNs from this patient was less than 10% of that in control PMNs, whereas the fibroblasts showed stimulated O2-.-release rates that were indistinguishable from those of fibroblasts obtained from healthy persons. Since the genetic mutation responsible for this type of CGD results in the absence of cytochrome b-558 in PMNs, fibroblasts should be affected in the same way if both cytochrome species were identical. These results suggest therefore that the low-potential b-type cytochromes in PMNs and fibroblasts are structurally and genetically distinct.

Recently, a superoxide-generating NADPH-oxidase system in human fibroblasts has been described. Therefore, we reassessed the possible use of this cell type for prenatal diagnosis of CGD patients comparing normal and CGD peripheral blood neutrophils (PMN) and skin fibroblasts in their reactive oxygen intermediate (ROI)-producing capacity. While PMN of the CGD patient showed a clearly reduced respiratory burst activity, which correlated well with the measured content of cytochrome b558, fibroblasts of the same individual showed no impaired production of superoxide anion or H2O2 upon stimulation by cytokines (TNF and IL-1) or other agents (Ca2+ ionophores and PAF, unpublished results). Furthermore, fibroblasts of the CGD patient or of normal donors could be inhibited in ROI production by diphenylene iodonium (DPI) and 2-iodobiphenyl. In contrast to PMN, no inhibition of the fibroblast NADPH-oxidase system was observed using staurosporin, an inhibitor of proteinkinase C. These data demonstrate, in contrast to previous studies, that fibroblasts are able to produce ROI. Nevertheless, since fibroblasts obtained from a CGD patient exhibited no difference in ROI production compared with fibroblasts obtained from healthy donors, they are not suitable for prenatal diagnosis of CGD.

Severe congenital neutropenia (SCN) can be corrected in vivo by treatment with pharmacological dosages of recombinant human granulocyte colony-stimulating factor (rhG-CSF). In order to analyze the decreased chemotaxis of neutrophils from SCN patients receiving rhG-CSF, neutrophil functions essential for chemotaxis were investigated. The mobilization of cytosolic calcium ([Ca2+]i) and the functional state of cytoskeletal proteins in neutrophils from SCN patients were compared with either neutrophils from healthy donors (or, in selected experiments, from patients with cyclic neutropenia) and neutrophils from patients with chemotherapy-induced neutropenia also receiving rhG-CSF. Using flow cytometric analysis, two neutrophil subpopulations were detected in SCN patients in response to N-formylmethionine leucyl-phenylalanine (FMLP) (10(-9) M to 10(-7) M), one of which was unable to respond to this stimulus with an increase in [Ca2+]i. Whereas a homogeneous increase in [Ca2+]i in normal neutrophils occurred at 10(-9) M FMLP, neutrophils from SCN patients required 10(-6) M FMLP to respond homogeneously with an increase in [Ca2+]i. In contrast, G-CSF induced neutrophils from patients with cyclic neutropenia and from patients with chemotherapy-induced neutropenia showed a normal increase in [Ca2+]i after stimulation. The [Ca2+]i-dependent superoxide anion (O2-) generation in response to FMLP was also significantly diminished in neutrophils from SCN patients compared to normal neutrophils. However, O2- generation elicited by phorbolester (PMA), which directly activates protein kinase C (PKC), was not affected in SCN neutrophils. The total immunoreactive actin content and basal F-actin content in neutrophils from SCN patients were elevated as compared to normal neutrophils and neutrophils from patients with chemotherapy-induced neutropenia. The increase in F-actin content following FMLP activation was much lower in neutrophils from SCN patients as compared with normal neutrophils. These data suggest a defect in the signal transduction pathway in neutrophils from SCN patients between FMLP ligand-receptor interaction and Ca2+ mobilization, whereas upstream of PKC, triggered events seem to be unaffected. Therefore, [Ca2+]i-dependent neutrophil function in response to FMLP, such as actin disassembly, chemotaxis and O2- generation are diminished in SCN neutrophils. The pathomechanism responsible for the defective [Ca2+]i increase might be an initial step in understanding the underlying pathophysiology of SCN.

Neutrophils from patients suffering from severe congenital neutropenia (SCN), who were receiving recombinant human granulocyte colony-stimulating factor (rhG-CSF), were investigated in order to analyze the previously described decrease in chemotaxis. This study demonstrated the decreased chemotaxis to five well-known chemoattractants, FMLP, C5a, IL-8, LTB4 and PAF. To further investigate this impairment of patients' neutrophils, receptors and receptor turnover for chemoattractants were examined using flow cytometry. We found 1) increased FMLP receptor and decreased C5a receptor expression, 2) a normal expression of intracellular FMLP receptors after incubation with PMA, 3) increased loss and decreased re-expression of FMLP receptors after incubation with this peptide, 4) normal expression of adhesion glycoproteins CR3 (CD11b/CD18) and LFA1 (CD11a/CD18), 5) further signs of in vivo preactivation: high expression of Fc gamma-RI (CD64) and Fc gamma-RII (CD32), decreased expression of Fc gamma-RIII (CD16), increased expression of CD14, and low expression of HLA-DR. These data demonstrate that the decrease of chemotaxis of neutrophils from SCN patients is not due: a) to a decrease in the number of intra- or extracellular FMLP receptors; b) to a decrease of adhesion molecules. However, the decreased chemotaxis could result from an altered FMLP receptor turnover. The relevance of the altered Fc gamma-receptor pattern for the in vivo occurrence of side-effects, e.g. the necrotic vasculitis, of G-CSF treatment is discussed.

The visible excitation and emission wavelengths of the recently developed fluorescent Ca2+ indicator fluo-3 permit analysis of the intracellular Ca2+ concentration, [Ca2+]i, in flow cytometry with a 488-nm argon laser. The role of [Ca2+]i in human polymorphonuclear leukocyte heterogeneity was investigated in response to formyl-methionyl-leucyl-phenylalanine (fMLP), C5a, and interleukin 8/neutrophil attractant/activation protein 1 (IL-8/NAP-1) by flow cytometry. The [Ca2+]i changes in different subpopulations within a heterogeneous cell suspension were resolved upon stimulation with fMLP. Using an anti-CD16 phycoerythrin-conjugated antibody and fluo-3 simultaneously, neutrophils affected and nonaffected in Ca2+ mobilization were distinguished in two patients suffering from glycogen storage disease type lb. In normal neutrophils, a different time course of Ca2+ mobilization of neutrophil subpopulations immediately after stimulation with fMLP was detected. In addition, after stimulation with a low concentration of IL-8/NAP-1 (10-10 M) two subsets of neutrophils appeared; one of them showed an increase in [Ca2+]i, while the other did not. These results indicate heterogeneity in the neutrophil signal transduction process involved in Ca2+ mobilization. Therefore, flow cytometric analyses can resolve changes in single-cell [Ca2+]i distribution patterns, which is important for the understanding of [Ca2+]i in neutrophil heterogeneous activation processes.

Patients with chronic granulomatous disease (GCD), and uncommon inherited disorder of phagocytes resulting in the defective production of reactive oxygen intermediates, are prone to bacterial and fungal infections. In the case presented, therapeutic efforts including white cell transfusions, and amphotericin B and IFN gamma administration were undertaken to treat pneumonia caused by Aspergillus fumigatus. During a phase of artificial respiration, transfused white cells in peripheral blood and bronchoalveolar lavage fluid were monitored in order to examine their kinetics and functional activity. Using flowcytometrical methods, host-derived and transfused neutrophils could be distinguished by cytochrome b558 expression using the monoclonal antibody 7D5 for immunofluorescent staining as well as by production of reactive oxygen intermediates. Transfused PMN could be detected in both compartments and their kinetics could be followed up to 24 hours after transfusion. Using flowcytometry, eve n small numbers of transfused PM could be measured during episodes of extreme leukocytosis. Since functionally intact transfused PMN were found in the bronchioalveolar lavage fluid, white cell transfusions in combination with antibiotic and immunomodulating therapy should be considered a part of the therapeutic regimens for life-threatening infections in GCD patients.

Neutrophils (and monocytes) from 5 patients suffering from severe congenital neutropenia (SCN) were investigated in vitro after induction of this cell type by treatment with recombinant human granulocyte colony-stimulating factor (rh G-CSF) in vivo. Some abnormal morphological features were seen, such as anomalies of nuclei of phagocytes. No limitations were found 1) in the ability of neutrophils and monocytes to produce reactive oxygen intermediates (ROI) following stimulation with phorbol-myristate-acetate (PMA), 2) in the ability of neutrophils to phagocytose particles of zymosan A and to produce ROI simultaneously and 3) in the ability to kill bacteria of the species staphylococcus aureus. However the specific migration of neutrophils in a gradient of FMLP under soft agar was decreased to approximately 50% in all patients tested as compared to healthy controls. In addition, spontaneous motility was decreased in one patient. Nevertheless, the good clinical improvements of patients suffering from SCN after treatment with rh G-CSF appeared to be due to induction of neutrophils displaying overall good functional activities with respect to natural defense.

Polysaccharides purified from large-scale cell cultures of the plant Echinacea purpurea were tested for their ability to activate human phagocytes in vitro and in vivo. These substances enhanced the spontaneous motility of PMN under soft agar and increased the ability of these cells to kill staphylococci. Monocytes were activated to secrete TNF-α, IL-6 and IL-1 whereas class II expression was unaffected. Intravenous application of the polysaccharides to test subjects immediately induced a fall in the number of PMN in the peripheral blood, indicating activation of adherence to endothelial cells. This fall was followed by a leukocytosis due to an increase in the number of PMN and a lesser increase of monocytes. The appearance of stab cells and some juvenile forms and even myelocytes indicated the migration of cells from the bone marrow into the peripheral blood. The acute phase C-reactive protein (CRP) was induced, probably due to activation of monocytes and macrophages to produce IL-6. In addition a moderate acceleration of the erythrocyte sedimentation rate was observed. Altogether, as in mice, the polysaccharides could induce acute phase reactions and activation of phagocytes in humans. The possibility of clinical use is discussed.

Dihydrorhodamine 123 (DHR) attached to membranes of granulocytes (PMN) and monocytes is caused to fluoresce by reactive oxygen intermediates (ROI) indicating the ability of phagocytes to produce these microbicide metabolites in a flow microcytofluorimeter. Whole blood samples from five boys with known chronic granulomatous disease (CGD) and from their mothers (and from one father and one grandmother), were examined following erythrocyte lysis in order to test this new method. An incubation period of 10 min with phorbol-myristate-acetate, followed by another 15 min incubation period with DHR before flow microcytofluorimetric analysis of 5 or 10 x 10(3) phagocytes, was sufficient to obtain the following results. PMN and monocytes from four patients with CGD could clearly not produce any ROI whereas cells from one patient displayed decreased activity in ROI production as compared to cells from a healthy donor. The X-linked mode of inheritance was detected in six carriers by the presence of two different cell populations (one normal ROI-producing and one negative or less active population). All the phagocytes from one mother produced ROI in normal amounts suggesting an autosomal mode of inheritance. All in all, the method presented provides a fast and most simple tool to diagnose CGD, to determine a decrease or total lack of ROI production and to establish the mode of inheritance of the disease.

A 15-year-old girl, suffering from recurrent stomatitis since the age of 7 years, turned out to be heterozygous for x-linked cytochrome b558-negative chronic granulomatous disease. Two different populations of neutrophils were found in her peripheral blood: one normal (ca. 44%) and one cytochrome b558-negative (ca. 56%) subpopulation which was unable to produce H2O2. There was no history of chronic granulomatous disease in the maternal family line and the blood from the mother and from the grandmother contained a single normal population of neutrophils only. Therefore a recent mutation in one of the x-chromosomes of maternal or paternal origin is most likely. We wish to emphasize that the possibility of a carrier status for chronic granulomatous disease should be considered if recurrent aphthous stomatitis occurs (especially in context with discoid lupus). An easy flow cytometrical method for H2O2 measurement on the single cell level is advised as a screening test [5]. Genetic counselling is a most important consequence of the correct diagnosis.

Analysis of the functional activity of phagocytes is of great importance in the differential diagnosis of patients with recurrent bacterial infections. Here we describe a method to determine the production of reactive oxygen intermediates (ROI) by microcytofluorometry using dihydrorhodamine 123, a derivative of rhodamine 123. Using this method the ROI production of erythrocyte-depleted whole blood samples can be measured without further time-consuming purification steps. Possible harmful manipulation of the isolated cells can also be avoided and highly reproducible and significant results are obtained in the minimum of time. This assay provides a very sensitive alternative to the clinically used NBT test in the diagnosis of patients with chronic granulomatous disease (CGD). Moreover, the analysis of oxygen-dependent effector functions of murine effector cells and cell lines may be important in investigating resistance to certain microbes (e.g., Candida albicans, Staphylococcus aureus or different protozoa such as Toxoplasma gondii or Leishmania species).

The T-cell subset distribution and the activity markers of 41 patients with multiple Myeloma, Waldenstrom's macroglobulinaemia and benign monoclonal gammopathy were repeatedly analysed using monoclonal antibodies (T3, T4, T8, anti-TAC, anti DR) and rosetting techniques. In myeloma and macroglobulinaemia the relative and absolute numbers of T4+ cells were diminished while the absolute number of T8+ cells was not decreased. No significant difference between stage I and III of the myeloma disease was seen. The diminished number of T4+ cells in myeloma was partly due to the effect of chemotherapy. Chemotherapy-induced lymphopenia resulted in a drop of circulating T4+ cells and an inverted T4/T8 cell ratio. Untreated patients with myeloma were not significantly different from patients with benign gammopathy. Patients with macroglobulinaemia differed from patients with myeloma as they had an increased absolute T8 cell count and a significantly elevated percentage of TAC+ (= IL 2 receptor expressing) cells. In macroglobulinaemia chemotherapy affected also the T8+ cell subset. Thus, patients with macroglobulinaemia, but not with myeloma appear to have activated T8+ cells in their circulation.

Two T-lymphocyte subsets develop in the thymus which differ in the expression of glycoproteins on their cell surface. About 60% of the circulating T cells express the glycoprotein T4, while about 30% have the glycoprotein T8. T4 and T8 cells can be determined in the peripheral blood or various organs with monoclonal antibodies. T4 and T8 cells differ in their antigen recognition, have different functions, and can cause various pathohistological changes. T4 cells recognize the antigen in association with the HLA-D/DR/DP determinants. Upon antigenic stimulation they liberate various factors and initiate and amplify an immune response (T4 = helper/inducer T-cells). They can also be cytotoxic and are mediating effector functions via macrophage activation. T8 cells recognize the antigen in association with HLA-A/B/C determinants. They exert their cytotoxic or suppressive effector functions mainly in viral infections. The T4 or T8 cell-mediated pathohistological changes are discussed in the light of the well studied T-cell infiltrations in lepra lepromatosa or lepra tuberculosa. The T4/T8 cell dyscrasia in the peripheral blood, described in a variety of infectious, autoimmune or immunodeficiency diseases, may be due to enhanced proliferation, selective sequestration, reduced production or the elimination of a subset. T-cell subset analysis in joints, bronchial lavages and tissues has clarified the pathomechanism in a variety of autoimmune diseases, although the etiology remains obscure. For example, in rheumatoid arthritis, multiple sclerosis, and sarcoidosis, a T4 cell-mediated reaction with macrophage activation can be found. T4/T8 cell analysis may also be of value in dissecting heterogenous diseases, e.g. systemic lupus erythematosus. Of value is also the additional demonstration of membrane components reflecting T-cell activation (IL-2 receptor or DR-antigen expression) which serves to identify the activated T-cell subset in peripheral blood. Finally, T4/T8 cell analysis can be helpful in deciding treatment, as the T-cell subsets have a different sensitivity to immunosuppressive drugs.