Inhibition of humoral and cell-mediated immune responses in man by distinct suppressor cell systems

Neutralization of interleukin-10 from CD14(+) monocytes enhances gamma interferon production in peripheral blood mononuclear cells from Mycobacterium avium subsp. paratuberculosis-infected goats

The gamma interferon assay is used to identify Mycobacterium avium subsp. paratuberculosis-infected animals. It has been suggested that regulatory mechanisms could influence the sensitivity of the test when it is performed with cells from cattle and that the neutralization of interleukin-10 (IL-10) in vitro would increase the gamma interferon responses. To investigate the regulatory mechanisms affecting the gamma interferon assay with cells from goats, blood was collected from M. avium subsp. paratuberculosis-infected, M. avium subsp. paratuberculosis-exposed, and noninfected goats. Neutralization of IL-10 by a monoclonal antibody resulted in increased levels of gamma interferon production in M. avium subsp. paratuberculosis purified protein derivative (PPDj)-stimulated samples from both infected and exposed goats. However, the levels of gamma interferon release were also increased in unstimulated cells and in PPDj-stimulated cells from some noninfected animals following neutralization. Depletion of putative regulatory CD25(high) T cells had no clear effect on the number of gamma-interferon-producing cells. The IL-10-producing cells were identified to be mainly CD14(+) major histocompatibility complex class II-positive monocytes in both PPDj-stimulated and control cultures and not regulatory T cells. However, possible regulatory CD4(+) CD25(+) T cells produced IL-10 in response to concanavalin A stimulation. The numbers of CD4(+), CD8(+), and CD8(+) gammadelta T-cell receptor-positive cells producing gamma interferon increased following IL-10 neutralization. These results provide insight into the source and the role of IL-10 in gamma interferon assays with cells from goats and suggest that IL-10 from monocytes can regulate both innate and adaptive gamma interferon production from several cell types. Although IL-10 neutralization increased the sensitivity of the gamma interferon assay, the specificity of the test could be compromised.

The CD8+ Leu-7+ subset of T cells in Crohn's disease: distinction between cytotoxic and covert suppressor functions

An expanded T cell subpopulation (CD8+ Leu-7+) has previously been reported in the peripheral blood of patients with Crohn's disease. This subpopulation of T cells was associated with a 'covert suppressor' function, particularly in patients with mild/early Crohn's disease, suppressing immunoglobulin production in vitro when cultured in the presence of pokeweed mitogen. T cells with the same CD8+ Leu-7+ phenotype have also been shown to exhibit non-major histocompatability complex-restricted cytotoxicity when triggered by anti-CD3 antibodies, and this cytotoxic activity has also been shown to be elevated in patients with Crohn's disease. Because cytotoxic cells can have immunoregulatory properties, we investigated the possible relationship between the cytotoxic and 'covert suppressor' functions of the CD8+ Leu-7+ subset of T lymphocytes in patients with mildly active Crohn's disease. Although the correlation between T cell cytotoxic activity and the CD8+ Leu-7+ cells was confirmed, no evidence for covert suppressor activity was found; there were no significant differences between the amount of IgM secreted by B cells from normal subjects and patients with Crohn's disease when cultured with T cells at increasing T:B ratios. In addition, IgM production by peripheral blood B cells did not correlate with either the number of CD8+ Leu-7+ cells or with the level of cytotoxic T cell activity. Furthermore, when B cells and CD4+ T cells were co-cultured with increasing numbers of CD8+ T cells, there was no evidence for excessive suppressor T cell activity in Crohn's disease. Although some patients exhibited low levels of IgM production, this was due to diminished B cell function, rather than excessive T suppressor activity or defective T helper activity. We conclude that the CD8+ Leu-7+ T cell subset is associated with cytotoxic but not with enhanced or covert suppressor activity in Crohn's disease. The previously described covert suppressor function attributed to cells with this phenotype in Crohn's disease was not found to account for diminished B cell responsiveness in vitro and is unlikely to be of major pathophysiologic significance in the majority of patients.

Immunological response to immunotherapy for immediate hypersensitivity: clinical relevance

Immunotherapy, also called desensitization, is effective in treating allergic rhinitis, insect sting venom hypersensitivity and probably allergic asthma. Administration of gradually increasing doses of the sensitizing antigen induces several immunological changes. The humoral responses include an increase in specific IgG titer, a decrease in specific IgE titer with blunting of its seasonal rise, and an increase in the specific anti-idiotype antibody titer. Cellular changes include diminished responsiveness of the patient's lymphocytes to stimulation by allergen as measured by thymidine incorporation. This is accounted for by the generation of suppressor cells specific for the allergen. These suppressor cells also induce suppression of IgE production by mononuclear cells. An additional effect that is attributed to IT is a decrease in basophil sensitivity to the allergen as measured by histamine release. The clinical correlates of these changes are not clear. Currently, none of the responses can be used as a tool for assessing the response in the treated individual patient. Although the increase in specific IgG was shown to correlate with the clinical response in patient groups, it is not applicable to the individual patient. Currently the best parameter for assessing clinical response is probably the increase in the ratio between the specific IgG and the specific IgE. However further studies are warranted to evaluate the significance of the change in anti-idiotype antibodies, basophil histamine release and perhaps immunological changes yet to be discovered.

Functional analysis of antigen-nonspecific T-cell suppression. I. Effect of mitogen-induced T suppressor cells on helper-T-cell clones

The effect of mitogen-induced nonspecific suppressor T cells (Ts)2 on T-helper-cell activity was investigated using isolated clones of murine T-helper cells as targets. TNP-self-reactive Thy1+, Ly1+ T-cell clones were isolated after continuous culture of T cells derived from picryl chloride-sensitized mice and were characterized by their ability to proliferate in an antigen-specific and MHC-restricted manner. In addition, selected T-cell clones were found to produce both interleukin-2 (Il-2) and T-cell replacing factor (TRF), lymphokines characteristic of helper T cells. Concanavalin A (Con A)-induced Ts cells inhibited the antigen-specific proliferation of these helper-T cell clones in a noncytotoxic manner even in the presence of exogenous Il-2. This implied that failure to proliferate was not merely due to an inability of these clones to produce Il-2. The kinetics of suppression also suggested that early T-cell activation signals were not affected. Furthermore, coculture experiments indicated that while proliferation could be severely inhibited, the actual secretion of lymphokines such as Il-2 and TRF by the T-helper clones was not. Our data suggest that nonspecific Ts modulation of proliferation versus helper factor production are under separate control in cloned T-cell populations, with lymphokine secretion remaining intact in the presence of Con A-induced Ts cells.

Long-term cultures of chronic lymphocytic leukemia B cells generate B suppressor cells

B suppressor cells (Bs) were generated by stimulation with PHA-P or concanavalin A of B cells from peripheral blood of B-cell chronic lymphocytic leukemia (B-CLL) patients. They suppressed well allogeneic mixed lymphocyte reactions. Long-term colonies of B cells from B-CLL were established for up to 6 weeks in liquid media, with B cells acquiring properties of suppressor cells while being cultured. Two types of cultures were observed: cells either grew in compact multicellular colonies or formed diffuse monolayers. Cells that remained alive in cultures for a number of weeks, but did not multiply, did not develop suppressive characteristics. Bs cells retained their phenotypic markers in cultures. Mitosis and lymphoblasts, but no differentiation into plasma cells, were observed. PHA-P-generated Bs were cultured in long-term colonies, retaining their suppressor properties. The establishment of long-term cultures of B-CLL cells may facilitate a better understanding of the nature and characteristics of normal and leukemic B cells.

Generation of B suppressor cells by phytohaemagglutinin

Activation by phytohaemagglutinin-P (PHA-P) of B cells from peripheral blood of healthy subjects generated B suppressor cells which inhibited allogeneic mixed lymphocyte reactions (MLR) and PHA-induced DNA synthesis. Their action was direct, that is, not mediated through the induction of T suppressor cells. The finding that B cells can be induced by PHA to become highly effective suppressor cells may have important clinical and experimental implications.

Inhibition of suppressor cell generation by mouse serum in culture

Normal C57BL/6 mouse spleen cells cultured for five days in the presence of fetal calf serum (FCS-induced suppressor generation culture) were shown, in mixing experiments, to suppress the primary humoral response of freshly explanted C57BL/6 spleen cells against sheep erythrocytes (SRBC). This suppressor cell generation was largely dependent on the FCS concentration in the suppressor generation culture. Ten or 5% FCS effectively supported the generation of suppressor cells, but 1% FCS only marginally supported it. When mouse serum (MS) from normal C57BL/6 mice was added to the suppressor generation culture, it inhibited the generation of the suppressor cells. Sera from allogeneic mice and athymic nude mice were also effective. The effect of MS was resistant to heat treatment (56 degrees C, 30 min). The inhibitory activity of MS was not dialyzable, and concentrated into the fraction which was not precipitated by 50% saturation of ammonium sulfate and which was eluted at a concentration of about 0.2 M NaCl from a DEAE-Sephadex A-50 column. The active fraction of MS also effectively inhibited the growth of Ehrlich tumor cells in culture. Further, MS also inhibited the generation of Con A-induced suppressor cells. The inhibition by MS of FCS-induced suppressor generation was eliminated by an interleukin 2-containing preparation.

Concanavalin A induction of suppressor activity in the T-helper subset defined by monoclonal antibodies

Human monocyte-depleted peripheral blood mononuclear cells were separated in T4+ and T8+ populations by a panning technique. Petri dishes coated with goat anti-mouse antibodies were plated by peripheral blood mononuclear cells coated by monoclonal antibodies, either T4 or T8. The cell populations were separated into adherent and non-adherent populations based on binding to the goat anti-mouse-coated plastic dishes. The purity of the adherent populations was 96%. T4+ and T8+ populations were used as effector cells in the concanavalin A-induced suppressor test. The T4+ population revealed a pronounced suppressor activity similar to that exhibited by the T8+ population. This finding was independent of two different sources of monoclonal antibodies, T4/T8 and OKT4/OKT8. The registered suppressor activity in the monoclonal antibody-defined helper population could not be explained either by a switch of the membrane phenotype from T4+ to T8+ cells or by an increased interleukin 2 consumption of the concanavalin A-treated cells.

T cell-B cell regulation in the intestinal lamina propria in Crohn's disease

Many patients with Crohn's disease have suppressor T cells circulating in the peripheral blood that are potent inhibitors of immunoglobulin synthesis in vitro. The purpose of this study was to examine the regulatory effects of T cells isolated from the lamina propria of patients with Crohn's disease or of patients with other diseases. Lamina propria cells were isolated from surgically resected intestine by sequential ethylenediaminetetraacetic acid and collagenase incubations. T cells were purified from lamina propria either by anti-F(ab)2' affinity columns or by a panning technique using monoclonal anti-T cell antibodies. Changes in the pokeweed mitogen-stimulated synthesis of immunoglobulin M, immunoglobulin G, and immunoglobulin A by normal peripheral blood indicator lymphocytes, as measured by sandwich enzyme-linked immunosorbent assay, was used as an index of help and suppression. Helper T-cell activity was sought by coculturing lamina propria T cells with normal peripheral blood cells plus pokeweed mitogen. Helper T-cell activity was found among lamina propria T-cell populations of patients and controls to a roughly comparable extent; help was provided for all isotypes. Suppressor T-cell activity was sought by coculturing lamina propria T-cells with normal B cells plus irradiated normal T cells plus pokeweed mitogen. No significant suppressor T-cell activity was observed in these cocultures, whether the cells were obtained from control intestine, the grossly uninvolved margin of Crohn's disease intestine, or actively inflamed Crohn's disease intestine. We conclude that suppressor T-cell activity of the sort found previously in the peripheral blood of patients with Crohn's disease is not demonstrable in the intestinal lesions of Crohn's disease. Helper T-cell activity is the predominant regulatory activity in both control and inflamed intestinal lamina propria.

Human blood B lymphocytes with receptors for sheep erythrocytes--their relevance in techniques to obtain T cells depleted of mature B cells

After B lymphocyte depletion, blood lymphocytes (PBMC) from certain individuals will generate substantial quantities of immunoglobulin (Ig) when cultured with pokeweed mitogen (PWM). The present investigations were aimed at analysing the cell subset in these T cell preparations, that was responsible for Ig production especially since the quantity of Ig generated was disproportionate to numbers of contaminating sIg-bearing B cells. Ficoll-Hypaque PBMC from 17 individuals were subjected to overnight sheep erythrocyte rosetting. Rosetted cells were subjected to very slow (100 X g) density gradient centrifugation to isolate T rosettes (and deplete PBMC of B cells). In 6 of these 17 individuals, such enriched T cells repeatedly generated substantial quantities of plasmacytoid cells after an 8-day culture in the presence of PWM and helper factors. Mean values for plasmacytoid cells per 1000 cells recovered were as follows: T cells 168.16 +/- 96.7 SD, B cells 226.67 +/- 161.1, PBMC 225.67 +/- 78.9. In further experiments, contaminating surface immunoglobulin (sIg)-positive B cells (less than 2% sIg-positive) were removed from the T cell preparations by the "panning" method, i.e. layering T cells on plates precoated with antisera specific for human Ig (polyvalent), and lysis of B cells with a monoclonal antibody BA-1. In these 6 individuals, removal of B cells by both these techniques completely abolished generation of plasmacytoid cells, thus confirming that it is a contaminating B cell subset which is responsible for Ig production in these T cell preparations. These data indicate that in certain individuals there are B cells that separate out with T cells during the E-rosette isolation procedure. With double immunofluorescence techniques, it became apparent that 4.8 +/- 1.3% of TRITC-labeled sIgM-bearing B cells were also labeled with FITC-conjugated monoclonal antibody to the sheep erythrocyte receptor. Kuritani and Cooper have previously demonstrated that PWM-responsive B cell precursors of IgM, IgG, or IgA plasmacytoid cells lack sIgD and, hence, comprise about 10-15% of the total B cells in PBMC. Our data would indicate that in certain individuals, about half this subset forms E-rosettes, which may explain why both E-rosette separated T cells and enriched B cells make similar quantities of plasmacytoid cells.

Spontaneous and Concanavalin A-induced suppressor activity in control and Hodgkin's disease patients

Indirect evidence suggests that abnormal regulation of B cells exists in Hodgkin's disease (HD) due, perhaps, to the sequestration of regulatory T-lymphocyte subpopulations in the spleen in this condition. Other work implicates the B-cell itself in this abnormality. In this study we have attempted to measure regulatory T-cell function by quantitating spontaneous and Concanavalin A(Con A)-induced suppressor activity in T-enriched spleen cells from control and HD spleens for pokeweed mitogen(PWM)-induced immunoglobulin (Ig) production. Using this polyclonal system, HD patients' spleen T-lymphocytes could not be shown to differ markedly from the control series. Cells capable of spontaneous and mitogen-induced modulation of Ig synthesis were present in both populations and showed a reciprocal relationship implying the activation of the same cell type. In this respect HD and control spleen resembled peripheral blood. A limited parallel investigation of PWM-regulatory activity in cells from spleen and peripheral blood from individual patients was also undertaken. Individual patients showed wide variation in suppression between the two compartments and, therefore, measurements of functional capacity in blood alone may not provide a true estimate of total regulatory capacity in lymphoma patients.

The effect of cimetidine treatment on suppressor T cells in duodenal ulcer patients

Changes in the suppressor T-lymphocyte activity were studied in 11 patients with duodenal ulcer during treatment with cimetidine. The drug was administered intravenously in a dose of 200 mg four times a day for a fortnight. Suppressor T-cell activity was determined by the Shou et al. method using two-stage culture before treatment, after 4 days of the treatment, just before drug withdrawal, and 2 days and 2 wk after the treatment. Suppressor T-cell activity significantly decreased soon after starting the treatment, remained low throughout the treatment, and rapidly and significantly increased following drug withdrawal.

Decreased macrophage-mediated suppression of lymphocyte activation in chronic renal failure

Prostaglandin-dependent adherent cell suppressor activity was assessed in patients with end-stage renal insufficiency. Proliferative responses of uremic peripheral blood mononuclear cells to optimal concentrations of phytohemagglutinin and concanavalin A were impaired. Responses to the galactosyl-directed lectins, soybean agglutinin and peanut agglutinin, were, however, normal or supranormal. The addition of 1 microgram/ml of indomethacin, to cell cultures resulted in relatively less potentiation of blastogenic responses to the galactosyl-directed lectins in cells from uremic patients (soybean agglutinin, p less than 0.02; peanut agglutinin, p less than 0.05). Similarly, depletion of adherent cells markedly enhanced blastogenesis induced by the galactosyl-directed lectins in normal cell cultures, whereas the effect was much less pronounced (soybean agglutinin, p less than 0.02; peanut agglutinin, p less than 0.02) in uremic cells. Reduced activity of the adherent cell suppressor system in patients with renal failure might be associated with altered sensitivity of uremic lymphocytes to soluble mediators of suppression. The lymphocytes of uremic patients, depleted of adherent cells, were relatively resistant to the inhibitory action of prostaglandin E1 (0.001 microgram/ml, p less than 0.05, and 0.01 microgram/ml, p less than 0.02) on galactosyl-directed, lectin-induced mitogenesis. In contrast, dibutyryl cyclic AMP (10(-4) M), 8-bromo cyclic AMP (10(-5) M), and 3-isobutyl-1-methyl xanthine (20 micrograms/ml) inhibited both control subject and patient cultures to the same extent. Prostaglandin E1 in combination with methyl isobutyl xanthine produced, in adherent-cell-depleted control subjects, levels of cyclic AMP that were significantly higher than in cells from uremic patients (p less than 0.05). Thus, depressed adherent cell suppressor activity in patients with renal failure may result in part from impaired generation of cyclic AMP by lymphocytes.

Induction of suppressor cell activity by human pregnancy serum

Third trimester pregnancy serum caused a dose-dependent inhibition of the one-way allogeneic mixed leukocyte reaction (MLR) through an effect that occurred during the first 48 hours of culture. Pregnancy serum also inhibited the mitogenic responsiveness of normal mononuclear leukocytes to concanavalin A (Con A) while the responses to phytohemagglutinin (PHA) and pokeweed mitogen (PWM) were less affected. Preincubation of normal peripheral blood mononuclear cells (PBMC) for 48 hours with 10% pregnancy serum enhanced a suppressor activity transferable with cells. These pregnancy serum-induced effector cells suppressed the MLR only when they were autologous to the responder population (p less than 0.05). The same suppressor cell preparation inhibited the proliferative responses of autologous PBMC to Con A (p less than 0.001) and PWM (p less than 0.05). These data suggest that one or more factors in pregnancy serum can induce or enhance suppressor cell activity in vitro. A comparable increase in suppressor cell activity in vivo may be responsible for blocking maternal rejection of the fetus and for the observed improvement in clinical activity of rheumatoid arthritis during pregnancy.

Comparative analysis of the suppression by cord blood mononuclear cells of adult and neonatal lymphocytes

The spontaneous or in vivo generated suppressor cell activity of adult and cord blood has been quantitated and compared in a system that examines the regulation of the T-cell response to mitogen. We confirmed previous findings that spontaneous suppressor cell activity is stronger in cord blood. This is only true, however, in a system that uses adult lymphocytes as responder cells. Cord blood responder cells are significantly more resistant to suppressor signals than are adult cells. Thus, the influence of cord blood suppressor cells on cord blood effector cells is equivalent to that seen in similar cocultures containing only adult cells. Spontaneous suppressor cell activity decreases rapidly among cultured adult cells but remains unaffected in cultures of cord cells for at least 4 days. Suppressor cell activity induced by concanavalin A (Con A) was significantly greater with adult cells. The sum of the spontaneous and Con A-induced suppressor cell activity among both cord and adult mononuclear cells was identical, indicating that the total potential suppressor cell function of the two populations is similar and that assays of spontaneous or Con A-induced suppressor cell activity are likely to be examining the same cell population. These findings strengthen the hypothesis that while fetal immunoregulatory cells may be potent suppressor of maternal (adult) lymphocytes, internal (fetal) balance is maintained by having responder cells relatively resistant to these fetal suppressor cells.

Immunoregulatory function of human intestinal mucosa lymphoid cells: evidence for enhanced suppressor cell activity in inflammatory bowel disease

Abnormalities in immune regulation at the gut level may be relevant to the pathogenesis of inflammatory bowel disease, but little is known about the immunoregulatory properties of intestinal mononuclear cells. Therefore, we wished to see if lymphoid cells derived from the lamina propria of surgically resected bowel specimens have any modulatory effect upon the immune response of peripheral blood mononuclear cells from patients with ulcerative colitis or Crohn's disease. When autologous peripheral blood and intestinal lamina propria lymphoid cells were mixed at different ratios and cultured in the presence of phytohaemagglutinin, we were able to show that intestinal mononuclear cells had the capacity to modify the mitogenic response of the cultured cells. These intestinal immunoregulatory cells, when obtained from mucosa affected by inflammatory bowel disease, express a significantly enhanced suppressor cell activity as compared with those from non-inflamed control mucosa. Such suppressor cell activity varies with cell concentration and requires cell proliferation, but it is independent of anatomical origin (small vs large bowel), type of inflammatory bowel disease (ulcerative colitis vs Crohn's disease) or immunosuppressive therapy. These findings point to an important functional difference between inflammatory bowel disease and control intestinal mucosa mononuclear cells. The enhanced suppressor activity of lamina propria mononuclear cells may be associated with impairment of cell-mediated immunity at the gut level. This may be related to the pathogenesis of inflammatory bowel disease by leading to defective intestinal immune regulatory events, which may not be detectable at the peripheral level.

Immunological reason for chronic ill health after infectious mononucleosis

In a group of patients who suffered from chronic ill health after an attack of acute infectious mononucleosis a disorder of T cell regulation was found. By means of cytochemical reactions the staining pattern associated with T suppressor cells was found in a greater percentage and that associated with T helper cells in a smaller percentage than in normal subjects. In a few patients this finding was confirmed in a functional suppressor assay. The patients were unwell for at least a year but most later made a complete recovery, which was associated with return to normal of the lymphocyte subsets.

The regulation of T cell responses by spontaneously active suppressor cells

In studying T cell regulation, peripheral blood mononuclear cells from normal subjects were examined for 'spontaneous', rather than mitogen-induced, suppressor cell activity. Normal blood leucocytes from 30 subjects included a subpopulation of cells capable of suppressing the response of lymphocytes to the T cell mitogen phytohaemagglutinin by 21-35%. The indicator system for these studies consisted of fresh normal lymphocytes stimulated by three concentrations of PHA in the presence or absence of normal but mitomycin C treated peripheral blood lymphocytes. To measure accurately the spontaneous suppressor cell activity, additional cultures were needed to control for the suppressive effects of crowding and metabolic competition. Allogeneic, cryopreserved 'B' cell enriched populations, supplied satisfactory control cells for this purpose. While allogeneic culture systems could induce significant suppressor cell activity after 7 days of co-culture, they could not induce this activity in the 3 days required to assay spontaneous suppressor cell effects. In developing this assay we noted that (a) crowding became a factor in the cellular response to mitogens with concentrations higher than 2 X 10(4) cells/well, (b) spontaneous suppressor cell activity decreased rapidly once cells were placed in culture and (c) both spontaneous and concanavalin A (Con A) activated suppressor cells could significantly reduce the response to PHA even when added to cultures established with mitogens 72 hr earlier. The ability to measure spontaneous suppressor cell activity in vitro will allow more physiological studies of the membrane markers and functional characteristics of these cells than is possible in conventional studies utilizing Con A. In addition, this assay allows the detection of enhanced in vivo activity of suppressor cells not easily detected in assays relying on mitogen induction of suppression. Such increased activity is thought to be an important factor in the pathogenesis of a number of human diseases.

Concanavalin-A-activated suppressor cells in patients with juvenile rheumatoid arthritis

Concanavalin-A-induced suppressor cell activity was investigated in 63 patients with a definite diagnosis of juvenile rheumatoid arthritis. Peripheral blood lymphoid cells from these patients did not have the same ability as cells from normal individuals to suppress the proliferative response of autologous cells, responding to phytohaemaglutinin, Candida albicans antigen, or allogeneic cells. No correlation was found between suppressor activity, disease activity, or number of joints involved. Nor was there any significant association between decreased suppressor cell activity and HLA-A, -B, -C, -D antigens, although there was a tendency towards association between decreased suppressor cell activity and HLA-B27.

Concanavalin-induced suppressor cells: characterization on the basis of corticosteroid and radiation sensitivity

Experiments were performed to examine whether the concanavalin A (Con A)- induced suppressor cells of several in vitro T- and B-lymphocyte functions constitute a functionally unique cell population. This study included simultaneous studies of three different assays of suppression of T- and B-lymphocyte functions. We found that Con-A-induced suppressor cells which inhibit the allogeneic mixed lymphocyte reaction (MLR) and the pokeweed mitogen-induced, plaque-forming cell (PEC) response are radiation sensitive at doses greater than 1000 rad, but corticosteroid resistant, while those suppressing allogeneic cell-mediated lympholysis (CML) are both radiation and corticosteroid resistant. These studies indicate either that Con-A-induced suppressor cells include heterogeneous populations which are differentially sensitive to corticosteroids and radiation, or that functionally distinct suppressor mechanisms are variably sensitive to these agents.

Heterogeneity of concanavalin A-induced suppressor T cells in man defined with monoclonal antibodies

Human peripheral blood T lymphocytes were enriched for OKT4+ or OKT8+ subpopulations using complement mediated lysis with OKT8 or OKT4 monoclonal antibodies. These subpopulations and unfractionated T cells were separately stimulated with concanavalin A (Con A) for a period of 48 hr and were then examined for their suppressive influence on proliferative response of autologous T cells to phytohaemagglutinin (PHA) or allogeneic non-T cells. Con A-activated unfractionated T cells, OKT4+ and OKT8+ T cell subsets markedly suppressed both these responses. Both OKT4+ and OKT8+ T cell subsets when enriched following Con A-activation of unfractionated T cells also caused significant suppression of proliferative responses of autologous T cells to PHA and allogeneic non-T cells in mixed lymphocyte cultures. The suppressive influence of Con A-activated T subsets was abolished by irradiation (2,000 rad) of activated cells. These studies indicate that Con A-induced suppressor T cells are heterogeneous. Precursors of Con A-induced suppressor T cells appear to reside in both OKT4+ and OKT8+ T cell populations.

Partial restoration of local GVH reaction in cancer patients by depletion of theophylline-sensitive suppressor T-cells

Theophylline-resistant T-cell subpopulations were assessed in terms of numbers and function among patients with disseminated cancer, and compared to normal controls. Within the total E-rosetting T-cells (65 +/- 6.5% for normal donors versus 34 +/- 1.0% for cancer patients; P less than 0.001) the proportion of theophylline-resistant Te cells was 56 +/- 1.5% and 26.6 +/- 1.1%, respectively (P less than 0.001). This significant difference in distribution between theophylline-resistant (effector) and theophylline-sensitive (suppressor) cells in favor of the latter was also reflected by the poor performance of unseparated T-cells in the local GVH reaction. Thus, the mean GVH reaction among normal donors was 159 +/- 30 mm3 versus 44 +/- 28 mm3 among cancer patients (P less than 0.001). Removal of the theophylline-sensitive suppressor T-cells resulted in significant augmentation of the local GVH reaction among normal donors and in significant, although partial, immune restoration of the local GVH reaction in some patients but not in others. The mean local GVH reaction after removal of theophylline-sensitive suppressor T-cells was 196 +/- 89 mm3 among normal donors and 68 +/- 46 mm3 among cancer patients (P less than 0.05). This immune restoration following depletion of suppressor T-cells was only partial among cancer patients because of an apparent intrinsic defect in the capacity of their effector T-cells to exert vigorous local GVH reaction. In one small group of four patients, this intrinsic defect was so profound that even after removal of the theophylline-sensitive suppressor cells, the restoration of the local GVH reaction was negligible (12 +/- 10.8 mm3 versus 24 +/- 9.8 mm3; P greater than 0.1). The quantitative and qualitative changes in effector and suppressor T-cell distribution during the development of the malignant process and the possible interaction between them are discussed.

Regulatory T cell-subset imbalance in chronic active hepatitis

Three monoclonal anti-T-cell antibodies, specifically directed against total T cells (OKT3), inducer-helper T cells (OKT4) and suppressor/cytotoxic T cells (OKT8), were used in this study to analyze peripheral T-cell subsets in hepatitis B surface antigen (HBsAg)-positive and -negative chronic active hepatitis (CAH) patients. Results showed that a clear-cut difference exists in the distribution of peripheral T cells of these two groups of subjects. HBsAg-positive CAH patients had a numerical predominance of peripheral T lymphocytes expressing the characteristics of cytotoxic/suppressor T cells. In contrast, patients with "autoimmune" HBsAg-negative CAH exhibit a predominance of OKT4 cells, namely, the helper-inducer T-cell subset. In addition, high numbers of circulating double labeled cells (expressing both the OKT4 and the OKT8 xenoantigens) were detected in some of the HBsAg-positive and HBsAg-negative CAH patients studied.

Induction of suppressor cells after activation of human peripheral blood mononuclear cells with sodium periodate

Pretreatment of normal human peripheral blood mononuclear cells (MN) with sodium periodate (NaIO4) resulted in the induction of suppressor cells. The mitogenic response of fresh allogeneic and autologous cells to phytohaemagglutinin (PHA), Concanavalin A (Con A), pokeweed mitogen (PWM), various antigens and in mixed lymphocyte culture was suppressed when NaIO4 pretreated cells were present. PWM-induced plaque-forming-cell responses were also suppressed by NaIO4-pretreated cells. Treatment of cells with mitomycin C before the NaIO4 treatment abolished the suppressive activity. A ratio of 1 : combination that resulted in the strongest suppression. Supernatants from NaIO4-pretreated cell cultures were not inhibitory.

Regulation in vitro of human natural killer (NK) cell activity

The natural killer cell activity of PBL from epidemic polyarthritis patients was depressed early after onset of symptoms but returned to normal as the patient recovered. This study found that the in vitro culture of Ross River virus, the agent responsible for epidemic polyarthritis, with PBL resulted in enhanced rather than depressed NK cell activity. Evidence was also obtained that NK cell activity could be suppressed by suppressor-T lymphocytes generated by culture of PBL with high concentrations of Concanavalin A. This suppressive activity was not due to release of a soluble mediator(s) by the suppressor T cells.

Characterization of a non-T, non-B human lymphocyte (L cell) with use of monoclonal antibodies. Its regulatory role in B lymphocyte function

These studies investigate the role of L lymphocytes in regulating terminal B lymphocyte differentiation. L cells have abundant Fc IgG receptors and comprise 10--15% of human peripheral blood mononuclear cells (PBMC). L cells lack the conventional markers of B and T lymphocytes and in culture, do not develop into B cells, T cells, or macrophages. Additionally, use of monoclonal antibodies failed to detect on L cells, surface antigens specific for B cells, T cells, and macrophages. In these studies, purified L cell subpopulations depleted of macrophages were co-cultured with autologous PBMC in the presence of pokeweed mitogen and at the end of 8 d, development of intracytoplasmic immunoglobulin (Ig) was determined. L cells were depleted of B and T cells by rosetting techniques and, in addition, by cytotoxicity techniques using monoclonal-specific antisera to T cells. In 14 individuals, L cells when co-cultured with PBMC, enhanced Ig synthesis by 83% +/- 62 SD, and also enhanced cell proliferation. Radiated L cells lost enhancing properties. To study the role of their high density Fc IgG receptors, L cells pretreated with IgG antibody-sensitized erythrocytes were used (i.e., after lysis of rosettes). Such L cells significantly inhibited Ig synthesis (by greater than 50%) despite promoting cell proliferation. Antibody-sensitized erythrocyte-rosetted macrophages did not inhibited Ig synthesis. Thus, positive and negative influences can be mediated by the same cell, depending on the state of Fc-receptor stimulation. Such cells may play a more prominent role in "feed-back" regulation of Ig synthesis by virtue of having abundant Fc IgG receptors.

Abnormalities of T-cell subsets in glomerulonephritis and systemic lupus erythematosus

In this study, three kinds of monoclonal antibodies directed at human T lymphocytes, produced by mouse hybridomas and termed OKT3, OKT4, and OKT8, were used in an indirect immunofluorescence assay, to analyze the distribution of peripheral T lymphocyte subsets in 41 patients with glomerulonephritis (GN) and 11 patients with systemic lupus erythematosus (SLE). As assessed by functional studies, OKT4 and OKT8 defined the helper and cytotoxic/suppressor T lymphocytes subsets, respectively, whereas OKT3 recognized all peripheral T-cells. Among GN patients, the ones presenting membranous GN (MGN), IgA disease, and lipoid nephrosis associated with segmental and focal hyalinosis (FGS) showed significant decrease of their peripheral cytotoxic/suppressive T cells. On the contrary, no significant alteration was found in the peripheral T cell distribution of patients with membranoproliferative GN (MPGN) and lipoid nephrosis associated with minimal-change GN (MCGN). Unexpectedly, there was a tendency for peripheral cytotoxic/suppressive T lymphocytes to be high in the majority of SLE patients, and only two of these subjects exhibited a relative decrease in peripheral OKT8 marked cells. The steroid therapy received by our patients might account for this discrepancy with previous reports of altered suppressor function in active SLE.

Lymphocyte suppressor cell activity in acute and chronic liver disease

We investigated lymphocyte suppressor cell activity in 53 patients with acute and chronic liver diseases. Suppressor cells were generated by preincubation of peripheral blood mononuclear cells (PBM) with concanavalin A (Con A) for 48 hr. Suppressor cell activity was evaluated by inhibition of Con A-stimulated blast transformation and by inhibition of pokeweed mitogen-induced immunoglobulin (Ig) synthesis of fresh allogeneic normal PBM in the second-set cultures. Of 29 patients with chronic active liver diseases (CALD), defective suppressor cell activities were observed in eight cases (28%) for Ig synthesis and 16 cases (55%) for blast transformation study. The suppressor cell activities were decreased in two (22%) of nine cases with chronic persistent hepatitis and one (17%) of six cases with inactive cirrhosis for both Ig synthesis and blast transformation. In contrast, suppressor activities were inducible in all nine patients with acute viral hepatitis. The histocompatibility antigen DR4 was significantly increased in CALD patients, but there was no correlation between this antigen and suppressor cell activity. These findings suggest that altered lymphocyte suppressor cells in patients with CALD may contribute to the continuing liver cell injury in this disease.

PUVA treatment in chromium hypersensitivity: effect on skin reactivity and lymphocyte functions

Two male patients with longstanding contact sensitivity to chromium were treated with PUVA. One patient, suffering from concomitant photosensitivity, reacted very favorably; his skin lesions cleared and light tolerance increased. This was paralleled by a decrease in the photopatch test reactivity and by the extinction of the patch-test reactivity on PUVA-exposed (pigmented) skin. Patch and photopatch tests on PUVA-shielded skin showed no decrease in skin test reactivity. PUVA-treatment caused a decrease in the number of rosette-forming T cells and an increase in lymphocyte stimulation in both patients. In one patient, abnormally high PHA-induced suppressor cell activities were recorded prior to treatment; after PUVA therapy the values were back to normal. In both patients, the PPD-induced suppressor cell activity of PWN response was clearly increased by PUVA-therapy. Other suppressor cell functions were not much affected. It is concluded that while PUVA-therapy may produce some systemic immunological effects, its abating effect on contact sensitivity and photosensitivity is mainly mediated through local mechanisms in the skin.

Con A-induced suppressor cell activity and T-lymphocyte subpopulations in peripheral blood lymphocytes of patients with rheumatoid arthritis and juvenile rheumatoid arthritis

Suppressor cell activity was investigated in peripheral blood lymphocytes from twenty patients with rheumatoid arthritis (RA) and twenty patients with juvenile rheumatoid arthritis (JRA) using a concanavalin A/mixed lymphocyte culture assay. The mean suppression in the RA patients was slightly reduced compared with the suppressor cell activity in adult controls (25 +/- 5% suppression compared with 37 +/- 5%; P less than 0.05, Student's t test), whereas the JRA patients had normal suppressor cell activity (mean 46 +/- 5% versus 43 +/- 5% in healthy children matched for age and sex). The RA patients had normal proportions of T-cell subpopulations, 13.3% T gamma cells and 49.8% T mu cells, compared with 13.8% and 58.0% in controls. The JRA patients, however, had a significantly reduced mean percentage of T gamma cells, 6.6%, compared with 13.8% in healthy children (P less than 0.05, Mann-Whitney U-test). The mean percentage of T mu cells was 53.7%, versus 56.2% in the controls. The relation between suppressor cell activity and suppressor cells enumerated by membrane markers is discussed.

Immunoregulatory T cell function in multiple myeloma

Multiple myeloma is a malignancy characterized by uncontrolled monoclonal B cell differentiation and immunoglobulin production. In most instances, there is concomitant reduction in polyclonal differentiation and immunoglobulin synthesis both in vivo and in vitro. In in vitro pokeweed mitogen-induced B cell differentiation assays, proliferation and polyclonal immunoglobulin secretion optimally requires T cell help and can be inhibited both by monocytes and suppressor T cells. Helper function and monocyte-mediated suppression are relatively radio-resistant whereas T suppressor function is sensitive to 2,000 rad x-irradiation. We have examined myeloma T cell subset function in this assay using recombinations of isolated patient and normal B cells, T cells, and T cell subsets. Monocytes were removed by a carbonyl iron ingestion technique, normal and myeloma T cells were fractionated on the basis of Fc receptors for immunoglobulin (Ig) G (Tgamma) or IgM (Tmu or T non-gamma), and proliferation and IgG secretion after co-culture determined by [(3)H]thymidine incorporation and radio-immunoassay, respectively. Myeloma B cells demonstrate quantitatively and qualitatively normal blastogenic responses and are appropriately regulated by either autologous or allogeneic T helper and suppressor subsets. Despite normal proliferation, however, myeloma B cells remain deficient in subsequent differentiation and immunoglobulin secretion even when co-cultured in the absence of monocytes or suppressor T cells and the presence of normal helper cells. Myeloma T cell populations, in contrast, are entirely normal in helper capacity over a range of T:B ratios but are markedly deficient in radiosensitive and concanavalin A-induced suppressor activity. T suppressor cell dysfunction in multiple myeloma is apparently due to a deficit in the T non-gamma suppressor subset, whereas Tgamma cells, although proportionately reduced, are functionally normal. This unique T suppressor deficit reflects the heterogeneity of suppressor mechanisms in this disease and may represent a compensatory response to the monoclonal proliferation or the involvement of regulatory T cells in the pathogenesis of the malignancy.