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We report here the successful selective cultivation of murine thymic mesenchymal reticular cells (MTMC) and murine thymic epithelial cells (MTEC) grown on extracellular matrix in the presence of defined medium. The selective growth of these two cell types was based on 1) conditions of tissue disruption and 2) differential growth requirements. Both cell types were dependent on transferrin, high density lipoproteins, insulin, hydrocortisone, and epidermal growth factor, whereas MTMC was dependent also on selenium and 3,5,3'-triiodothyronine. The elimination of single factors or extracellular matrix resulted in specific and different changes in the growth pattern of each cell subpopulation. Cells of both types exhibited the ultrastructural features of high metabolic activity. The epithelial nature of MTEC cultures was defined by bundles of tonofilaments and desmosomes and by positive staining to keratins and negative to vimentin. In addition MTEC were positively stained with mAb to thymic medullary epithelial cells and by Ulex europeus agglutinin, and were able to form Hassall's corpuscles, suggesting their medullary origin. MTEC were also H-2 and Ia positive. In contrast MTMC were positive for vimentin and periodic acid-Schiff, low positive for H-2, and negative for keratin and Ia. Both cells did not contain nonspecific esterase, nor did they phagocytize latex beads. With the use of all these criteria we classified MTEC as epithelial cells from the medullary compartment of the thymus and MTMC as reticular cells of mesenchymal origin.

Two morphologically distinct primary cultures of murine thymic stroma were established and found to be of epithelial (MTEC) and mesenchymal (MTMC) origin. These cultures were generated by selective conditions of tissue disruption and were maintained on extracellular matrix in defined medium. Culture supernatants (CS) from these cultures (EC-CS and MC-CS respectively), were tested for cytokine production and for effects on thymocyte maturation. Both supernatants displayed the activities of IL-3 and of granulocyte/macrophage-CSF and not of IL-1, -2, -4, or IFN. In addition they were found to be mitogenic to murine thymocytes in a "spontaneous" [3H]TdR incorporation assay. The two supernatants differed, however, in their effect on Con A stimulation. EC-CS had a strong enhancing effect, both when used for preincubation (18 h) before Con A stimulation or when present simultaneously with it. MC-CS had a small inconsistent effect under these conditions. Also EC-CS enhanced IL-2 and IL-3 production by thymocytes. The responsive thymocyte subpopulation was the one that does not bind peanut agglutinin. CS of an established thymic epithelial cell line displayed only part of these activities at a considerably lower level. CS from primary kidney cell culture was completely devoid of activity. The results suggest that primary thymic stromal cell cultures, cultivated under the defined conditions described here, may better preserve physiologic secretory activities, and probably also other cell functions, compared with established cell lines. Furthermore, the results are compatible with the hypothesis that the soluble factors, secreted by thymic stromal cells, are active on either very early or late stages of thymic differentiation, whereas the main intrathymic stages of differentiation are conceivable dependent primarily on direct contact with stromal cells.

This article examines whether it is possible to target vulnerable households within a geographically defined area. It looks first at the justification for targeting and then reviews recent practical experience in actually trying to reach vulnerable groups. As complex emergencies increasingly last longer, strategies to target vulnerable households are common in the protracted phase of the emergency. While this is often necessary because of a decline in resources, it is not always justified by an improvement in nutritional status or food security of the beneficiary population. Common target groups are the poor and the malnourished, but in complex emergencies these are not always the most vulnerable. Moreover, recent practical experience has shown considerable difficulties in targeting the poor. Methods to target the poor rely on community-based relief committees, whose priorities are not necessarily the same as those of external agencies. This paper gives examples of such targeted assistance programmes in Kenya, south Sudan and Tanzania. The paper concludes that situations where targeting vulnerable households is justified and feasible are extremely limited. It is suggested that if targeting has to be done because of scarce resources, this should be done on a geographical basis and on the basis of nutritional status. Case-study material shows that it is essential to understand the political determinants of vulnerability and to design methods that will reach the most vulnerable.

Apoptosis of normal thymocytes was shown to be triggered by several mechanisms (e.g. glucocorticoids, gamma-irradiation). In the present study the authors report on thymocyte apoptosis that is induced by thymic epithelial cells. The thymocytes undergo a massive apoptotic death within 24 h of cocultivation with thymic epithelial cell monolayers derived from primary cultures (PTEC) or from a thymic epithelial cell line (TEC). Non-thymic monolayers were inactive. Apoptosis induction in this experimental model requires direct contact between the thymocytes and the thymic epithelial monolayer and can be blocked by anti-CD2 and anti-LFA-1 antibodies. The immature CD3-/+dull CD4+CD8+ thymocytes were the cells which undergo apoptosis. The fact that the authors are dealing with a massive apoptotic process of immature cells in the absence of exogenous antigen suggests that it involves the nonselected thymocytes. The apoptotic pathway selected by thymocytes following their culturing on TEC involves p53 expression. Indeed it was found that TEC-induced apoptosis, led to the accumulation of p53 protein that preceded the step of DNA fragmentation in freshly isolated thymocytes as well as in a glucocorticoid resistant thymoma cell line. Since glucocorticoid-induced thymocyte apoptosis is p53-independent, glucocorticoids are conceivably not involved in TEC-induced thymocyte death. The in vitro experimental model presented here may reflect the physiological sequence of events leading to thymocyte death in the thymus.

Aim To describe what proportion of acutely malnourished children, aged 0 to Methods A total of 33 programme databases, from 12 countries, collected between 2002 and 2008, with a total of 118 180 individuals (range 59–22 473 per data set), were obtained for analysis as part of the Management of Acute Malnutrition in Infants project. The authors excluded data from 93 511 individuals because they were either duplicates (1389), had age data missing or were ≥60 months (15 643), had sex data missing (15), had programme care type data missing (971) or did not received TFP care (75 493); leaving a final sample of 24 669 individuals. TFP treatment models included day centres (DC), home treatment (HT), stabilisation centres and therapeutic feeding centres. Results Overall, young infants accounted for 16.2% (n=4002) of admissions, ranging from 10.2% to 26.4% in HT and DC programmes, respectively. Prevalence of oedematous malnutrition was lower in young infants than in children (p Conclusions In this study, young infants account for an important proportion of TFP admissions for the treatment of acute malnutrition. Malnutrition profile differed to that in children, with significantly less oedema. Worse infant outcomes suggest the need to improve infant-specific management: neither infants nor children met SPHERE standards for cure (>80% programme cure). There were significantly more infant deaths. Future research is needed to determine whether our findings are representative of all acutely malnourished young infants.

In previous reports we described our approach to the cultivation of murine and human thymic epithelial cells in primary cultures, using defined, serum-free growth factor-supplemented medium and extracellular matrix-coated culture plates. The cells in these cultures displayed high metabolic activity and their supernatant was highly active on thymocytes. In the study reported here we analysed cytokine activities in the supernatant of human thymic epithelial cell cultures (HTES), by using the respective cytokine-dependent cell lines and by neutralization with specific monoclonal antibodies. Three cytokine activities were detected--interleukin-6 (IL-6), granulocyte colony-stimulating factor (G-CSF) and macrophage (M)-CSF. Other cytokine activities tested for [IL-1, IL-2, IL-7, interferon (IFN) and tumour necrosis factor (TNF)] were negative. The effect of HTES on concanavalin A (Con A)-induced proliferation of murine thymocytes could be completely abolished by anti-IL-6 antibodies, but not by antibodies to CSF, whereas enhancement of bone marrow cell proliferation by HTES was partially inhibited by either anti-G-CSF or anti-M-CSF antibodies and completely inhibited by both antibodies, but not at all by anti-IL-6. We can thus distinguish between thymocyte-related cytokines (IL-6) and bone marrow (myeloid/monocyte) related ones (G-CSF, M-CSF) in HTES.

We report here on a new approach to the cultivation of human thymic epithelial (HTE) cells, which apparently allows more faithful preservation of cell function. This approach, previously developed by us for mouse thymic epithelial (MTE) cells, is based on the use of culture plates coated with extracellular matrix (ECM), and on the use of serum-free, growth factor-supplemented medium. The nutritional requirements of HTE and MTE are somewhat different. Although both are critically dependent on ECM and insulin, they differ in their dependency on other growth factors: selenium and transferrin are much more important for HTE cells, whereas epidermal growth factor and hydrocortisone play a more essential role in MTE cultures. The epithelial nature of the cultured cells is indicated by positive staining with anti-keratin antibodies and by the presence of desmosomes and tonofilaments. The ultrastructural appearance of the cells further suggests high metabolic and secretory activities, not usually found in corresponding cell lines. The culture supernatant (CS) of HTE cells exhibited a strong enhancing effect on thymocyte response to Con A stimulation, as measured by cell proliferation and lymphokine production. The effect was observed on both human and mouse thymocytes, but was much stronger in the homologous combination. Thymic factors tested in parallel did not have such a differential effect. The dose-effect relationships were in the form of a bell-shaped curve, with fivefold enhancement of response at the peak and a measurable effect even with 1:1000 dilution, when human thymocytes were used. The responding thymocytes were those which do not bind peanut agglutinin and are resistant to hydrocortisone. The culture system described here may have advantages for the in vitro study of thymic stromal cell function.

Several viruses have been evaluated as potential agents for cancer treatment using either their oncolytic properties, in order to lyse cancer cells, or their potential augmenting effects on the immune response to tumors. However, the direct oncolytic effect was found to be limited in time, in scope and in specificity, whereas the use of viral oncolysates to augment antitumor immunity was shown to be better than tumor cell homogenates or extracts but inferior to noninfected intact tumor cells, attesting for the importance of membrane architecture in preserving immunogenicity of tumor specific surface antigens. In order to get the maximum benefit from this approach we selected a nonlytic virus-tumor cell combination, using Newcastle disease virus as a nonpathogenic virus, to treat the experimental tumor model, Lewis lung carcinoma (3LL) in mice. The virus effectively infected 3LL cells without any cytopathic effect. The infected cells induced strong antitumor immunity, as judged by the appearance of immune cells in the spleen (Winn test and lymphocytotoxicity) and by the resistance to challenge with the 3LL cells after immunization. The antitumor immunity was superior to that obtained with intact noninfected tumor cells. We also designed a treatment protocol using the same virus-tumor cell preparation to treat mice after tumor inoculation. This treatment resulted in cure of 40% of the animals.(ABSTRACT TRUNCATED AT 250 WORDS)

A human colon adenocarcinoma cell line was used to study junction formation and disassembly. Monolayered cells grown to confluency have desmosomes but no gap or tight junctions. Treatment with trypsin, while causing the breaking up of desmosomes to hemi-desmosomes, resulted in a rapid assembly of junctions. Tight junctions were formed in some recognizable steps: elevation of particle-free membrane ‘crests’, alignment of particles on these crests, and fusion of these particles to form typical tight junctions ridges. Gap junctions were also formed on particle-free membrane areas, but comparatively few such junctions were formed. Cycloheximide had no effect on the assembly of junctions. It is therefore assumed that pre-existing membrane particles were rearranged into junctions and that this rearrangement is probably due to the increased mobility of the trypsinized cell membranes. Transfer of trypsinized cells back into trypsin-free fresh medium resulted in internalization of phagocytic-like vesicles containing tight junctions elements.

The specific immune response of patients with cutaneous leishmaniasis including the ability of their lymphokines to enhance the monocytes' leishmaniacidal activity was studied. In 16 patients with cutaneous leishmaniasis, their concanavalin A-induced lymphocyte proliferative responses, interferon-gamma and interleukin 2 activities and the ability of their concanavalin A-induced lymphokines to kill monocyte intracellular amastigotes were not different from normal controls. Antigen-stimulated lymphocyte cultures showed that 13 of 13 patients had an increased lymphocyte proliferative response; 11 of 16 produced interleukin 2 and 12 of 13 produced interferon-gamma; in addition, 10 of 11 of these antigen-induced supernatants increased the monocytes' killing of Leishmania major amastigotes. Antibody levels to parasite membrane antigens determined by radioimmunoassay showed that 8 of 13 titers were greater than 10 and 4 of 13 titers were 2 to 10 times higher than control. Our findings demonstrate that patients with cutaneous leishmaniasis elicit a specific immune response to L. major antigens and part of this response is the production of lymphokine capable of promoting monocyte killing of intracellular amastigotes.

The humoral and cellular components of the antibody-dependent cellular cytotoxicity (ADCC) against allogeneic human colonic tumour cell lines were evaluated. The 2 colon cell lines used in this study (HT-29 and ACC-20) were found by immunofluorescence to have carcinoembryonic antigen (CEA) on their surface, and to become sensitive to the lytic effect of unstimulated lymphocytes after coating with heterologous anti-CEA. This reaction was used to evaluate the ADCC activity of mononuclear cells from the peripheral blood of patients with gastrointestinal cancer (mostly local extensive colo-rectal). Remarkable variability was found in the lytic capability (2-50% specific lysis) of both cancer and non-cancer mononuclear cells, with no significant difference between them. Sera from 127 cancer patients and 91 non-cancer patients were tested, using the reaction with heterologous anti-CEA as positive control and as a reference point. In 46 cases (21%) the sera were reactive in this system, and 43 of them were of Blood Group O. However, there was no difference between the cancer patients and the normal controls. The antigenic determinant involved in this reaction is not the Blood Group A specificity but, most probably, a polypeptide common to CEA and A (as shown in the following publication). In addition, trials for the elimination of the non-tumour-specific reaction, by absorption or inhibition, failed to disclose a tumour-specific one. The value of the ADCC assay in monitoring human tumour immunity, and possible ways of eliminating reactivity to normal antigens in this system, are discussed in the light of these findings.

The relationship between carcinoembryonic antigen (CEA) and A antigenic determinants on the cell surface of colon-tumour cells was studied by the ADCC assay. Antiserum prepared in 2 rabbits to an undecapeptide analogous to the amino terminal of CEA(1-11) was found by us either to participate in (Rabbit 2) or specifically inhibit (Rabbit 1) ADCC. The binding spectra of these two antisera and of antiserum to the whole CEA molecule were similar. All of them react with A and non-A colon-tumour cells as well as red blood cells of Type A (RBC-A) and their activity was completely absorbed on RBC-A but not on B or O. O-type, ADCC-reactive human sera always react with A-type colon-tumour cells and RBC-A, and some of them with non-A colon-tumour cells also. The degree of inhibition of their reactivity by anti-CEA(1-11) R1 varied between sera, from none to almost a complete inhibition, and is not related to whether the serum is of cancer or non-cancer origin. Non-reactive O-type sera contain anti-A activity demonstrable by haemagglutination and immunofluorescence. However, they cannot participate in ADCC reaction nor inhibit it. The sera, which contain lymphocyte-dependent antibody to A-type colon-tumour cells, lysed RBC-A, without the addition of lymphocytes or complement, in an immunologically specific way. It is concluded that the reactivity seen in our ADCC system is related to a determinant common to A and CEA (and maybe to other normal cross-reacting antigens) which most probably resides in the amino terminal part of these molecules. This determinant elicits the production of lymphocyte-dependent antibodies in about 50% of people with blood group O. Thus, the amino terminal part of CEA is not a tumour-specific part of the CEA molecule. No specific anti-tumour activity was found in patients' serum by this method, and claims for its demonstration by other methods may well be related to the non-specific activity observed here. ImagesFigure

The thymic extract TP-1 significantly enhanced the production of immune interferon (IF) by human peripheral blood mononuclear cells in Con A- or Raji- but not PHA-induced cultures. TP-1 effect was more pronounced under conditions of low IF production. The effect was evident before cell proliferation took place and without necessary concurrent effect of TP-1 on the blastogenic response. TP-1 had no detectable effect on nonactivated cultures. The enhancement of IF production by TP-1 to the degree demonstrated here necessitates consideration of its possible effects in every assay of thymic hormones that involves lectin or allogeneic stimulation of lymphocytes.

Both native human IFN-beta or -gamma added to human monocytes in culture increased their leishmaniacidal effect on intracellular Leishmania tropica major (L. major) amastigotes. This effect was dose-dependent, and was apparent if the IFN was added either before or after infection of the monocyte cultures with the promastigote form of the parasite. Compared on the basis of antiviral activity, IFN-gamma was shown to have a leishmaniacidal effect approximately three times greater than IFN-beta. Recombinant IFN preparations showed similar effects. In addition, IFN-gamma increased H2O2 production from human monocytes in culture in a dose-dependent manner. Monoclonal antibody to IFN-gamma abrogated both its effect on the leishmaniacidal capacity and on H2O2 production by the monocytes. These results suggest that IFN-gamma may be of therapeutic value in cutaneous leishmaniasis.

A partially purified thymic factor, thymostimulin (TS), significantly increased the survival rate of adult, immune-intact mice infected with the neurotropic Mengo virus. TS treatment was begun after virus inoculation by daily i.p. injections. In untreated C57BL/6 mice, LD50 was reached with 1 X 10(4) PFU, but 10-fold more virus (i.e., 1 X 10(5) PFU) was needed to reach LD50 in TS-treated animals. TS effect on survival, though, could be observed with several virus doses (1 X 10(3) to 1 X 10(6) PFU) (p less than 0.001). A significant effect on survival was also observed with outbred ICR mice (p less than 0.005). Serum interferon (IFN) levels in the Mengo virus-infected mice were relatively low (average peak 300 U/ml), but were significantly increased (two- to ninefold) in the TS-treated mice. Peak serum levels were reached earlier in TS than in control animals (24 hr and 72 hr, respectively). Both acid-labile and acid-stable type I IFN production were augmented by TS in the Mengo virus-infected mice. Natural killer activity was also enhanced by TS, in particular on the second day after virus inoculation. In addition, MP-virus was used as a second, unrelated virus challenge. This virus caused a nonlethal infection, with relatively high levels of serum IFN (average peak 10,000 U/ml). TS increased IFN levels (two- to eight-fold) also in this challenge system. In conclusion, TS causes a nonspecific enhancement of endogenous production of IFN and has a significant effect on the survival of lethally infected mice. The data indicate a potential application of thymic factors for the treatment of viral infections.

The proliferative response (PR) of T lymphocytes in PHA stimulated cultures (5 μg/ml and 0·5 μg/ml; 72 hr) was used to assess the suppressive capabilities of peripheral blood mononuclear cells (PBMC) in the thyrotoxic phase of Graves' disease and their possible modification by propylthiouracil (PTU) and methimazole (MMI) treatment. Graves' patients had 50% higher PR than controls. Treatment with PTU (n=6) for 9·5 weeks (mean) or MMI (n=6) for 18 weeks (mean) resulted in continuous decrease in PR, starting after 3 weeks and down to control values and plateau at 7-10 weeks. This decrease correlated with the decline in plasma thyroxine (T4) levels which had already dropped by 3 weeks. Grouped according to thyroid functional state PR was significantly decreased only in the euthyroid state. Suppressor cell function, expressed as suppressor removal index (PR of PBMC pre-incubated for 24 hr/PR of fresh PBMC), was significantly lower in Graves' patients compared to controls and reached above normal values under PTU treatment: 0·98±0·16, 1·39±0·09 and 1·94±0·19 (mean±s.e.m.) respectively. A direct suppressive effect of PTU in culture, observed in normal subjects, did not exist in untreated patients and evolved under MMI treatment to above normal levels. The cell-mediated PTU effect, exercised by PBMC pre-incubated with PTU on autologous cells pre-incubated in medium alone, increased under PTU treatment to above normal levels. Both this cell-mediated suppressive effect and augmented PR of pre-incubated cells were already significantly increased after 3 weeks of PTU treatment, when all patients were still thyrotoxic. We conclude therefore that PBMC of patients in the untreated, thyrotoxic phase of Graves' disease are deficient in an active cell-mediated suppressive function, a deficiency corrected—with compensatory overshoot—during anti-thyroid drug treatment.

Fifteen patients with single or multiple lesions of cutaneous leishmaniasis were randomly assigned to apply either IFN-beta-containing cream or a placebo cream base. Despite 8 weeks of therapy no significant improvement of the lesions was achieved. Although topical IFN-beta was not effective in this study, several laboratory studies suggest that IFN, particularly IFN-gamma, may be of therapeutic value in cutaneous leishmaniasis.

The structural patterns of tight junctions in normal human colon mucosa, colon adenocarcinomas, and fetal colon were studied and compared by the freeze-fracturing technique. The zonula occludens of the normal colon cells at the upper, more differentiated part of the crypts of Lieberkühn appeared as continuous belts made of about eight parallel strands. At the less differentiated bases of the crypts, the zonula occludens was less regular and contained fewer, mostly beaded strands. In the colons of 10-week fetuses, early stages of tight junction assembly were observed. At the same time, vesicles bearing remnants of tight junction elements were observed within the cytoplasm. This finding suggested that during the early development and organization of the fetal gut, mechanisms of assembly and disassembly of tight junctions are operating concomitantly. In well-differentiated adenocarcinomas, the cells in the luminal region retained their polarity and had seven or eight parallel junctional elements. In infiltrating cells, however, tight junctions appeared as fascia occludens and resembled the junctional organization of 10-week fetuses.

The alkylating agent 1(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) caused a prolonged suppression of antibody response to sheep red blood cell challenge in mice. Two phases of suppression could be observed, an early (first three weeks after CCNU administration) and late phase (4-10 weeks). The late immunosuppression was more severe than the early one. Treatment by the thymic extract thymostimulin (TP-1R) caused a complete recovery of antibody response, with overshoot, during early phase, but only partial recovery during late phase. It is suggested that the known CCNU induced damage to stem cells, manifested at late phase, reduces the responding pool for the restorative effect of thymostimulin.

One hour incubation with the thymic extract TP-1 induced reciprocal effect on B and T rosette formation in lymphocytes of human peripheral blood. The percentage of mouse erythrocyte rosette-forming cells among lymphocytes of chronic lymphatic leukaemia was decreased by TP-1 from 54.5% to 27.1% (P < 0.001). No such effect was observed in healthy adult or cord blood lymphocytes. On the other hand, the percentage of sheep erythrocyte rosette forming cells increased significantly after TP-1 treatment, but only under conditions of active rosette formation and not in the total rosette assay. This increase was highly significant in three conditions with relative deficiency of cell-mediated immunity: newborns (17.1 to 28.3%), cancer patients (24.5 to 31.7%) and patients with lepromatous leprosy (19.8 to 31.8%). Only a small increase was noticed in healthy adults. A similarly prepared spleen extract was not active in either B or T rosette assays.

The effect of treatment with the thymic factor thymostimulin (TP-1) on the survival rate of tumor-bearing mice was studied, using C57BL/6 mice inoculated with 1 x 10(5) Lewis lung carcinoma (3LL) cells. TP-1 given from inoculation day (4 mg/kg, twice weekly) caused a delay in the appearance of primary tumor [14.4 +/- 1.1 (S.E.) days in control; 18.5 +/- 1.4 days in TP-1-treated animals; p less than 0.05], without changing ultimate survival rate. When primary tumor was resected, the incidence of fatal lung metastasis increased as a function of tumor size on resection day. TP-1 given after resection (same dose schedule) significantly increased survival rate as compared to resection only, provided that resected tumor diameter was less than 1.7 mm. The combination of TP-1 and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU; single i.p. injection, 50 mg/kg) was effective in either resected or nonresected primary tumor. Without resection, TP-1 with CCNU cured (more than 6 months free of tumor; untreated animals died within 30 to 44 days) 55% of the animals, as compared to 23% cured by CCNU alone (p less than 0.01). With resection animal cure rates were: resection (resected tumor diameter, 0.7 to 1.7 mm) alone, 42% cured; resection with CCNU, 47% cured; resection with TP-1, 70% cured; resection with CCNU and TP-1, 100% cured (last two groups significantly different from resection only). The results indicate a profound effect of TP-1 in prolonging life and increasing cure of tumor-bearing mice. This effect was manifested when tumor load was small and was apparently more pronounced on metastatic than on primary tumor.

Transformed fibroblasts in interphase and normal fibroblasts in mitosis were agglutinated by Con A and the lectin from wheat germ, whereas normal fibroblasts in interphase and transformed fibroblasts in mitosis were not agglutinated by these lectins. The percentage of fluorescent cells at non-saturation concentrations of fluorescent ConA was also higher with transformed interphase and normal mitotic cells, than with normal interphase and transformed mitotic cells. Under the same conditions, a similar number of radioactively labeled ConA molecules were bound to normal and transformed cells in interphase and mitosis. Our results indicate different cyclic changes in the surface membrane of normal and transformed fibroblasts, so that regarding interaction with these lectins, normal mitotic cells resemble transformed interphase cells and transformed mitotic resemble normal interphase cells. The data suggest that there is a reversed cyclic change in the mobility of specific surface membrane sites in normal and transformed cells.

The effects of concanavilin A (Con A)-induced lymphokines from human peripheral blood mononuclear cells, enriched helper and suppressor lymphocyte populations and recombinant interferon-gamma (IFN-gamma) on the ability of monocytes to promote killing of intracellular Leishmania major (L. major) amastigotes and to induce the production of hydrogen peroxide (H2O2) was examined. All these mitogen-induced supernatants contained active IFN-gamma. There were no differences in the ability of these supernatants or IFN-gamma to promote the monocyte killing of the L. major amastigotes or H2O2 production. An increase in H2O2 production by monocyte monolayers was observed following the addition of either of these supernatants or IFN-gamma alone. In addition, a marked increase in the production of H2O2 was observed following priming with either of these mitogen-induced supernatants or IFN-gamma and the addition of a second stimulus, phorbol myristate acetate (PMA). Monoclonal antibody to IFN-gamma abrogated the increase in production of H2O2 by all these mitogen-induced supernatants; however, this antibody only resulted in partial inhibition of the leishmaniacidal effect of these lymphokines on human monocytes. These results would suggest that IFN-gamma is the component of the lymphokine that is largely or exclusively responsible for H2O2 production, while other factors in addition to IFN-gamma are important in promoting oxygen-independent mechanisms for the killing of intracellular L. major amastigotes.

37 patients with cutaneous malignant melanoma (MM) were randomized, after surgical removal of tumor, to either no further treatment or to adjuvant treatment by the thymic factor thymostimulin (TS; Tp-1 Serono). 26 patients were with primary (stage I) MM (tumor thickness greater than 1.25 mm), and 11 patients with local or regional disease spread (stage II MM). Randomization was done separately for each disease stage. Life table analysis of the results indicates that significantly (p less than 0.01) more patients were free of disease at one year on study if treated by TS than if left untreated. Probability of survival was also better (p = 0.05) in the TS-treated group at 15 months on study. No side effects, toxic or allergic, were observed under TS treatment.

Recombinant interferon preparations caused a dose-dependent increase of human monocyte cytotoxicity to the K562 and Daudi cell lines. Both rIFN-gamma and rIFN-beta enhanced this function to a similar extent, while rIFN-alpha c had less effect when compared on the basis of their anti-viral effects. Endotoxin and concanavalin A increased basal monocyte cytotoxicity while phagocytosis of latex particles had no effect. The increased monocyte cytotoxic effect of rIFN-beta was completely abrogated by monoclonal antibody to IFN-beta, while monoclonal antibody to IFN-gamma had no effect. However, monoclonal antibody to IFN-gamma only reduced the increased cytotoxic effect caused by rIFN-gamma by 25%. Catalase inhibited both basal monocyte cytotoxicity and the increase in cytotoxicity following addition of rIFN-gamma only slightly, suggesting that mechanisms other than the oxidative burst were active and could be induced by rIFN-gamma.

A new type of human interferon (IFN), IFN-alpha-C, produced in Escherichia coli and purified on monoclonal antibodies, was given at a dose of 3 X 10(6) u (3 micrograms)/day to a terminally ill unsplenectomized patient with hairy cell leukemia, who had had severe recurrent infections and pancytopenia. There was marked reduction in the size of the spleen after 2 weeks, and platelet counts returned to normal after 1 month of treatment. The IFN treatment also raised the granulocyte counts and hemoglobin levels, improved the normal repopulation of the bone marrow, and restored resistance to infections. IFN-alpha-C was well tolerated, without serious side effects, and treatment has been continued for 10 months.

Thymostimulin (TS), a partially purified thymic factor, has a significant impact on tumor development in C57B1/6 mice inoculated with Lewis lung carcinoma (3LL) cells, as judged by its effect on time of tumor appearance after tumor cell transplantation. In a previous study, we determined the conditions under which survival rate of the tumor-bearing mice can be significantly increased by TS treatment. In the study communicated here we analyzed host defense mechanisms that are modified by TS treatment in the tumor-bearing mice. In general, immune parameters that were increased or stimulated by the presence of the tumor were further increased in the TS-treated animals (number of lymphoid spleen cells, their response in mixed lymphocyte tumor cultures, their natural killer cell activity, and their ability to produce colony-stimulating factor), or reached earlier maximum levels (spontaneous [3H]thymidine incorporation, a reflection of in vivo spleen cell activation). Responses which reflect tumor-induced immunosuppression (proliferative response induced by phytohemagglutinin or concanavalin A stimulation) were restored to normal level by TS. Specific tumor-related reactions (specific cell-mediated cytotoxicity) were preserved in the TS-treated animals. The wide spectrum of TS effects had, nevertheless, certain elements of selectivity; e.g. colony-stimulating factor, but no interferon production is enhanced by TS in the tumor-bearing mice in diametric contrast to TS effect in Mengo virus-infected mice. The spectrum of TS effects was also dependent on the type of tumor cell used. The results indicate that the significant effect of TS on 3LL tumor development in mice is associated with a strong, multifaceted effect of TS on the immune system.

Herpes and papilloma virus infections will probably be among the first indications for which interferon (IFN) will find its place as a therapeutic agent. The data to be analysed below suggest that, when properly used, interferon offers the combination of efficacy and safety that has not been achieved thus far by any of the other currently available treatments for these two viral infections. However, in order to put this analysis in its proper framework, it will be appropriate to precede it with a short comparative description of the viruses and the diseases caused by them.

The aim of this communication is to increase awareness to specific problems of certain population sectors whose immunological system may be more sensitive to toxic damage than the normally functioning system. Indeed, the title of the presentation was selected with three considerations in mind: (a) It is possible and instructive to compare therapeutic immunomodulation, with which there is relatively more experience, and immunotoxicity, and by doing so to gain better insight into the general rules and potential mechanisms of toxic effects on the immune system. Moreover, therapeutic immunomodulatory agents are known to cause immunotoxicity under certain circumstances (Shoham, 1984a) and, in principle, the reversed situation is also possible. (b) Conditions of “deficiency”,“in sufficiency” or “failure” of the immune system may amplify or modify the effect of either type of agents. Accordingly, these conditions call for more caution and specific attention to potential adverse effects of such agents, which could cause further deterioration of the deficient immune system. Moreover, conditions of immunodeficiency are important targets for the therapeutic use of immunomodulating agents and these conditions may give rise to toxicity rather than benefit as as an outcome of this therapeutic manipulation. (c) There are certain similarities between the effect of age (either too young or too old) and malnutrition on the immune system, which justify considering them together in connection with potential toxic damage.

The effect of direct contact between thymic stromal cells and thymocytes on differentiation markers and functions of the latter was studied. The thymic stromal cells included two epithelial and one fibroblast cell lines, previously described. Murine thymocytes were incubated with confluent monolayers of these cells or their supernatants for 24 hr, using monolayers of non-thymic cells and their supernatants as controls. Then, the thymocytes were tested for changes in expression of several surface antigens [Thy-1, Lyt-1, Lyt-2, L3T4, IL-2-receptor (IL-2R)], spontaneous [3H]thymidine incorporation (STI), lectin-induced proliferative response (PR) and lymphokine (IL-2 and IL-3) production. All three thymic stromal cell lines reduced the expression of Thy-1, Lyt-1 and Lyt-2 significantly. The expression of L3T4 was also reduced in some of the experiments, while IL-2R was not expressed by the thymocytes, neither before nor after the co-culture. The thymic stromal cell lines also increased the spontaneous [3H]thymidine incorporation and lymphokine production by the thymocytes and inhibited their proliferative response to lectins. Under the same experimental conditions, the culture supernatants of the thymic stromal cells and the non-thymic cells did not have any effect on the thymocytes, either when collected and used separately or when used in a co-culture system which allowed thymocyte contact with the medium but not with the stromal cells (Transwell system). These results suggest a specific effect of thymic stromal cells, epithelial as well as fibroblasts, on thymocyte maturation. The effect is mediated by direct cell contact and not by secreted factors.