Functional analysis of two human T-cell subpopulations: help and suppression of B-cell responses by T cells bearing receptors for IgM or IgG

Serum beta 2-microglobulin as a marker of activity in systemic lupus erythematosus

A prospective study of 62 patients with systemic lupus erythematosus (SLE) was performed in order to establish whether serum beta 2m could be a good marker of clinical activity. beta 2m was determined by radio-immunoassay and the values compared with a control group of healthy individuals. The mean value of beta 2m in the control group was 1.48 +/- 0.52 mg/l and 2.87 +/- 2.19 mg/l (p less than 0.001) in the SLE group, 4.53 +/- 2.89 mg/l in the 22 patients with active disease and 2.40 +/- 1.80 mg/l (p less than 0.001) in the 40 patients with inactive disease. High beta 2m values (greater than or equal to 3 mg/l) were observed in 64% of the patients with active SLE, VS. only 12% of the patients with inactive disease (p less than 0.001). Significant differences were also observed when beta 2m of the patients with inactive SLE was compared with the control group (p less than 0.001). The beta 2m with a sensitivity of 64%, a specificity of 87%, and an efficiency of 79% could be a good parameter to detect SLE clinical activity.

Human monocyte cell line (U937) releases suppressive IgG-binding factor(s)

Fc gamma receptor-bearing U937 cells, when incubated in serum-free buffer, were found to release spontaneously a suppressor material for pokeweed mitogen-drigen IgG synthesis which could be retained on Sepharose 4B-IgG immunosorbents. Immunosorbents coupled with IgM or F (ab')2 fragments of IgG were unable to retain the inhibitory activity of U937-derived material, suggesting a binding specificity for the Fc gamma fragment of IgG. This suppressor material corresponds therefore by definition to an IgG-binding factor (IgG-BF). The mechanism for in vitro suppression of the antibody response by U937-derived IgG-BF was investigated. It did not interfere with cell proliferation and displayed maximum effect when added at day 3 of the culture period. Tested for its effect on IgG, IgM and IgA synthesis, IgG-BF suppressed antibody production following a pattern specific for IgG. Finally gel filtration of the suppressor material gave rise to two peaks of inhibitory activity with an apparent molecular mass comprised between 30 to 40 kDa and 60 to 73 kDa, respectively.

Response of Peyer's patch lymphocyte subsets to Giardia muris infection in BALB/c mice. II. B-cell subsets: enteric antigen exposure is associated with immunoglobulin isotype switching by Peyer's patch B cells

The aim of this study was to quantify the response of Peyer's patch B cells, surface IgA-bearing (sIgA) B cells, and surface IgM-bearing (sIgM) B cells to Giardia muris infection. Following infection of a cohort of immunocompetent BALB/c mice with G. muris cysts, Peyer's patch cell suspensions were prepared at serial time points during the infection, incubated with fluorescein-conjugated monoclonal antibodies directed against murine leukocytes, B cells, sIgA B cells, sIgM B cells, or T cells, and analyzed by flow cytometry. Of total Peyer's patch leukocytes, the percentages of B cells, sIgA B cells, and sIgM B cells in uninfected BALB/c mice were 64.7 +/- 2.0% (mean +/- SEM), 30.3 +/- 1.5%, and 52.5 +/- 2.4%, respectively. The total number of Peyer's patch leukocytes increased significantly (1.8 X) during G. muris infection, and returned to control levels as the infection was cleared. The percentages of Peyer's patch T and total B cells did not change significantly during Giardia infection. However, sequential changes were observed in the percentages and numbers of sIgM and sIgA B cells during the infection. Peyer's patch sIgM B cells rapidly increased in percentage and number, reaching maximum levels 1 week after cyst inoculation. After remaining constant the first week, the number of Peyer's patch sIgA B cells increased during the second week of G. muris infection, reaching a maximum level 11-14 days after cyst inoculation. The data support the hypothesis that immunoglobulin isotype switching in Peyer's patches is induced by antigen exposure.

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.

The intrinsic radiosensitivity of lymphocytes in chronic lymphocytic leukaemia, quantitatively determined independently of cell death rate factors

Survival curve shape for lymphocytes X-irradiated in vitro is governed by death rate as well as intrinsic radiosensitivity. We have resolved into these two components the survival curves obtained for CLL lymphocytes by use of a simple mathematical model. A multiple correlation coefficient comparing the predicted with the experimental survival curves was close to unity (0.954-0.999). For 14/18 patients with unequivocal B-cell CLL, the leukaemic (colchicine ultrasensitive) cells behaved as a homogeneous population (D37 0.32-1.28 Gy). This is similar to the more radiosensitive class of lymphocytes of normal blood (believed to include the B cells) and is some 4-fold less than the more radioresistant class (comprising most of the T cells). The lethally hit cells were homogeneous in death rate, which followed first order kinetics. The half-life (range 9-87 h) was, on average, some 50 per cent shorter than the more radiosensitive normal lymphocytes. The remaining four patients constituted a miscellaneous group. From one of these, it can be seen that an excessively slow death rate can give the misleading impression of radioresistance. It is hypothesized that the benefit afforded certain CLL patients treated with low-dose total body irradiation (TBI) or splenic irradiation (SI) may reside, partly, in the sparing of T lymphocytes of the helper type and in accompanying selective elimination (or functional inactivation) of those of the suppressor type.

Increased IgG secretion by unstimulated mononuclear cells in active multiple sclerosis and functional assessment of the T8 subset

Unseparated mononuclear cells (10(5) cells/well) were cultured both in the presence and absence of pokeweed mitogen (PWM), and IgG secretion was measured by radioimmunoassay. In unstimulated cultures, levels of IgG secretion were found to be higher in a group of patients with multiple sclerosis (MS) than in control groups of healthy individuals or patients with other neurologic diseases (OND). By contrast, PWM-induced IgG secretion was similar in MS patients and in controls. In MS patients, levels of IgG secretion greater than 2500 ng/ml in unstimulated cultures were present in 29 (58%) of 50 patients with active disease and in only 3 (14%) of 21 patients with inactive MS (P less than 0.01; MS active vs inactive). Furthermore, levels of IgG secretion in unstimulated cultures were higher in patients who had abnormalities of circulating T-cell subsets consisting of reduced numbers of suppressor/cytotoxic (T8) cells and elevated helper:suppressor (T4:T8) ratios. In additional experiments using isolated populations of T-cell subsets, T8 cells from MS patients who had low percentages of circulating T8 cells were found to suppress PWM-induced IgG secretion by autologous cells to a similar extent as controls, suggesting that in vitro, T8 cells function normally in these patients. In vitro IgG secretion by unstimulated mononuclear cells in MS appears to be a further reflection of abnormal immune regulation in this disease.

Inhibitory effect of PWM-stimulated OKT4+ subsets on erythro-, granulo- and megakaryocytopoiesis in vitro

Normal human peripheral blood T cells and T-cell subsets defined by monoclonal antibodies of the OKT series were pretreated with pokeweed mitogen (PWM). Their effects on the haematopoietic precursors, erythroid (BFU-E, CFU-E), granulocyte-macrophage (CFU-GM) and megakaryocyte (CFU-M) colony forming cells were evaluated by coculture. While unstimulated T cells and T-cell subsets enhanced growth of autologous blood BFU-E, PWM-stimulated T and OKT4+ cells suppressed it, also inhibiting proliferation of both autologous and allogeneic bone marrow BFU-E, CFU-E, CFU-GM and CFU-M. PWM-stimulated OKT8+ cells had little effect on the growth of any of the precursors at the cell concentration at which growth was completely inhibited by PWM-stimulated OKT4+ cells. Irradiation of T or OKT4+ cells with 3000 rad before PWM stimulation completely abrogated the inhibition. These observations might be related to the mechanism of pancytopenia in some cases of immune-mediated aplastic anaemia.

Functional properties of a unique subset of cytotoxic CD3+ T lymphocytes that express Fc receptors for IgG (CD16/Leu-11 antigen)

A subset of peripheral blood T lymphocytes coexpressing CD3 and IgG Fc receptors (FcR) (CD16/Leu-11 antigen) have been identified, isolated, and functionally characterized. The CD3+, CD16+ cells were established in short-term culture using growth medium containing interleukin 2 (IL-2). Both the freshly isolated cells and the cultured cell line stably expressed the CD3+, CD16+ phenotype. Furthermore, a majority of these T cells lacked either CD4 or CD8 expression. Like in vitro-activated cytotoxic T lymphocytes and natural killer (NK) cells, the CD3+, CD16+ cells showed numerous azurophilic granules. Although these cells failed to mediate significant levels of NK cell-mediated cytotoxicity even after stimulation with IL-2, they efficiently functioned as effectors of antibody-dependent cellular cytotoxicity (ADCC). The Ig isotype specificity of the ADCC was analyzed using an isotype switch-variant family of a murine anti-HLA monoclonal antibody (mAb). Similar to the CD3-, CD16+ NK cell population, the CD3+, CD16+ T cells preferentially used the IgG2a antibody to mediate ADCC. The CD3+, CD16+ cells demonstrated a proliferative response when cocultured with either a NK-sensitive tumor cell line, K562, or a NK-insensitive B lymphoblastoid cell line, CCRF-SB. The response against CCRF-SB was significantly inhibited by anti-IL-2 receptor antibody, whereas the response against K562 was only partially diminished. Cytotoxicity was also induced in the CD3+, CD16+ population by the presence of anti-CD3 mAb, indicating that cytotoxicity can be triggered by stimulation via the CD3-T cell antigen receptor complex. By isolating these CD3+, CD16+ cells from the peripheral blood of a normal, healthy individual, it has been possible to extensively study the morphology, antigenic phenotype, and functional behavior of this unique subset of T lymphocytes expressing IgG FcR.

The generation of interleukin-2-dependent suppressor T-cells from patients with systemic metastasis of gastric carcinoma and the phenotypic characterization of the cells defined by monoclonal antibodies

Suppressor cells, which might be activated in patients with gastric carcinoma, were successfully enriched by the use of interleukin-2 (IL-2) prepared from human tonsils and spleens. That is, peripheral blood lymphocytes cultured for 3 or 4 weeks with IL-2 strongly inhibited the patient's own lymphocyte-proliferative responses to alloantigen or phytohemagglutinin (PHA). Quantitative fluorescence measurement for immunologic analysis of phenotypic characterization of the cells was made on FACS-IV with monoclonal antibodies anti-Leu-1 anti-Leu-2a, anti-Leu-3a, anti-Leu-4, anti Leu-5, anti-Leu-7, and anti-HLA-DR and goat anti-human immunoglobulin (Ig). Functional suppressor T-cells expanded with IL-2 showed the following phenotype: Leu-1+ Leu-2a+, Leu-3a-, Leu-4+, Leu-5+, Leu-7-, HLA-DR+, human Ig-. The IL-2-dependent suppressor T-cells could be obtained only when the cells were derived from patients with systemic metastasis of gastric carcinoma. These findings suggest that generation of IL-2-dependent suppressor T-cells is the result of large tumor burdens; this may exert negative cellular control in the immune responses, thus inducing the status of the lower cell-mediated antitumor immunity, and may promote cancer progression in gastric cancer patients.

Relationship between immune system and gram-negative bacteria. III. Functional analysis of human peripheral blood lymphocyte subpopulations separated by cytoadherence with Salmonella minnesota Rb

Spontaneous adherence of bacteria to human peripheral blood mononuclear cells (PBMC) represents a useful tool for analysis of lymphocyte subsets with different functions. We have recently shown that PBMC can be divided into 2 populations based on their ability to bind Salmonella minnesota R345 (Rb) bacteria. By using these procedures, here, we provide evidence that Rb-bound and Rb-unbound PBMC populations give similar proliferative responses to phytohemagglutinin (PHA) and concanavalin A (Con A), while the pokeweed mitogen (PWM)-induced proliferative and differentiative responses are higher in the Rb-unbound than in the Rb-bound PBMC fraction. Moreover, enhanced PWM-induced responses are obtained in Rb-unbound cell cultures enriched for T4+ cells. When B (non-E rosetting) cells are cultured with purified T lymphocytes from the Rb-bound (T-Rb+) and Rb-unbound (T-Rb-) fractions, comparable PWM-induced mitogenic responses are observed. The T-Rb- population contains a higher percentage of cells expressing T4+ phenotype, and when added to B cell cultures a more elevated PWM-induced IgA, IgG and IgM synthesis is observed than in B cell cultures containing T-Rb+ cells. These results suggest that the T-Rb- fraction is enriched for T cells which help IgA, IgG and IgM responses.

Release of granulocyte-macrophage colony-inhibiting activity by normal human postthymic precursor cells

Seven normal human peripheral blood cell fractions (buffy coat, mononuclear cells, non-T, T, Fc-IgM receptor-depleted T-lymphocyte, Fc-IgG receptor-depleted T-lymphocyte, and autologous rosette-forming T-cell-depleted T-lymphocyte subpopulations) treated with phytohemagglutinin (PHA) were examined for the production of granulocyte-macrophage colony-stimulating activity (CSA). It was found that medium conditioned by a T-lymphocyte subpopulation depleted of autologous rosette-forming T-cells (Tar cells, a postthymic precursor subpopulation that inhibits Ig synthesis) stimulated colony-forming units of granulocyte and macrophages (CFU-GM) to a greater extent than did the other conditioned media (CM) analyzed. Based on this finding, CM from an enriched Tar subpopulation was prepared and thus showed that PHA-treated Tar cells release a factor capable of inhibiting CFU-GM growth. The inhibitory activity of this factor persisted-after heat inactivation, suggesting that cause of the colony-inhibiting activity (CIA) is other than interferon. Further studies revealed that Tar-derived inhibitory factor acts either directly upon CFU-GM or via monocytes/macrophages (M phi/Ma), enhancing CIA, and not the level of CSA production by M phi/Ma. The overall data are interpreted as demonstrating the presence of CIA in a specific T-lymphocyte subpopulation that may represent a new relationship between lymphocytic and myelocytic systems in the human.

Modulation of the immune response by immunoglobulin for intravenous use. I. Inhibition of pokeweed mitogen-induced B cell differentiation

The effect of a commercially available intravenous gammaglobulin preparation (IgSRK; Sandoglobulin) on the antigen-non-specific activation of the immune system was examined using pokeweed mitogen (PWM)-induced B cell differentiation. In cultures of peripheral blood mononuclear cells from 16 normal donors, IgSRK (300 micrograms/ml) inhibited PWM-induced generation of plaque-forming cells by 76% (P less than 0.001), whereas human serum albumin (300 micrograms/ml) induced no significant inhibition (5%; P not significant). The IgSRK-mediated suppression was demonstrable in both serum-containing (76%) and serum-free (63%) media, and monomeric IgSRK suppressed as effectively as did heat-aggregated IgSRK. F(ab')2 fragments exhibited no inhibitory capacity (mean inhibition -11%; P not significant) suggesting that the Fc portion of IgSRK may be required for suppression. In addition, IgSRK had to be added to the cultures at their initiation to effect full inhibition. These studies suggest a potential beneficial pharmacological role for IgSRK in the treatment of disorders characterized by pathogenic autoantibodies, but also warn of a potential deleterious effect of inhibiting the host's humoral response to an infectious challenge.

The relationship between membrane characteristics, functional reactivity of T-lymphocytes, and the progression rate of B-cell chronic lymphocytic leukemia

Study performed on 192 patients has demonstrated that the progression rate of chronic lymphocytic leukemia (CLL) is associated with the existence of T-cell defect(s). A dynamic classification system based on evaluation of tumor mass growth rate, response to therapy, and myelopoietic failure (MF) has been devised for evaluation of progression rate of CLL. Besides four basic groups (Group 1: CLL without therapy; Group 2: CLL on therapy, without remission; Group 3: CLL on therapy, partial remission; Group 4: CLL on therapy, complete remission) patients were further classified into phase (type) A (stable, indolent CLL) or phase (type) B (active, progressive CLL). The major criteria for phase A were: total tumor mass (TTM) doubling time (DT) longer than 12 months, no MF, and/or good response to therapy. The major criteria for phase B were: TTM DT less than 12 months and/or accompanying MF and/or no response to therapy. The following major findings have been demonstrated: (1) altered quantitative relationship between active and nonactive parts of T-cell compartment (E/A ratio) in the progressive phase of CLL; (2) altered B/T gamma ratio in the progressive phase of CLL; (3) more than 50% increased percentage of T gamma cells in the stable phase of CLL; (4) very low stable and absent seeding efficiency of T-cells in the progressive phase of CLL; (5) altered (delayed) DNA synthesis pattern in the progressive phase of CLL; and (6) negative local xenogeneic graft versus host reaction in the progressive phase of CLL. Based on reported results, a hypothesis regarding the possible role of T-cells in the pathogenesis of CLL was suggested.

Cells and mediators which participate in immunoglobulin synthesis by human mononuclear cells. I. The obligatory requirement of null lymphocytes in the synthesis of immunoglobulins in vitro

The circulating mononuclear cells of normal adult human volunteers were fractionated into T and non-T lymphocytes. The T cells were then fractionated into TM and non-TM cells and the non-T cells were further fractionated, by both positive and negative isolation, into B cells and null cells. Culture of non-T cells, TM cells, and PWM for 7 to 8 days resulted in cytoplasmic Ig (cIg) synthesis by all B cells, as detected by immunofluorescence. However, culture of either purified B or null cells with TM cells and PWM resulted in a marked reduction (75%) of cIg-synthesizing cells. The addition of monocytes did not enhance cIg synthesis. Culture of reconstituted B and null cells with TM cells and PWM restored the capacity to synthesize cIg to the cells. It is concluded that null cells are required, as well as TM cells and PWM, for cIg synthesis by B cells.

Lymphocyte function in recurrent aphthous ulceration

Lymphocyte blast transformation responses to mitogens and to streptococcal, adenovirus Type 1, and oral mucosal antigens were studied in 32 patients with recurrent aphthous ulceration (RAU) and matched control subjects. RAU patients showed significantly depressed (p less than 0.05) responses to mitogens in comparison with matched controls, but there was no significant difference between patients and controls in response to any of the antigens tested. These results indicate that neither cell-mediated hypersensitivity to streptococcal or viral antigens nor cross-reactivity between oral mucosal and streptococcal antigens are likely to play a role in the pathogenesis of RAU. Rather, the data support the hypothesis of an imbalance or defect in immune cell subpopulations.

T cells with receptors for IgD

The role of IgD in the immune response has been elusive, although its predominance on the cell surface suggests a receptor function. We have shown previously that euthymic but not athymic BALB/c mice, injected with IgD before antigen, exhibit enhanced antibody responses which can be transferred by T cells. Isotype-specific T cells have been reported to have both upward and downward immunoregulatory effects. Here we demonstrate the existence of T cells with receptors for IgD, and show that exposure to IgD in vivo or in vitro significantly increases the number of T delta cells in the spleen and lymph nodes but not in the thymus. The kinetics of T delta-cell appearance in vivo parallels that of the immunoenhancing effect which occurs after injection of IgD. These T delta cells are of the Lyt 1+2- T-cell phenotype.

Regulatory roles of T mu and T gamma cells in the collaborative cellular initiation of the extrinsic coagulation pathway by bacterial lipopolysaccharide

The Shwartzman reaction is a classic biologic response in which the coagulation system is activated in vivo. Cellular initiation of the extrinsic coagulation protease cascade can be mediated by one or more limbs of the lymphoid response to diverse biological stimuli. The T cell-instructed monocyte and macrophage responses that have been implicated are mediated by a number of different cellular pathways and are elicited not only by antigens and allogeneic cells but also by other stimuli such as immune complexes and the lipid A moiety of bacterial lipopolysaccharide (LPS). The latter response has been implicated in the pathogenesis of the disseminated intravascular coagulation associated with bacterial infection. In the rapid collaborative cellular pathway response to LPS, we have described a relatively rigorous requirement for T helper cells in induction of the biosynthesis of tissue factor and Factor VII by monocytes. To elucidate potential regulatory aspects of this cellular procoagulant response, we provide the first evidence for the existence of T suppressor cells for the cellular procoagulant response to LPS by the rapid T cell-instructed pathway. Human peripheral blood lymphocytes were separated by cytoaffinity into Fc gamma-positive and Fc mu-positive cells and were characterized for their functional properties in the procoagulant response. T mu cells mediated the monocyte response, consistent with their identity with instructor cells. T gamma cells suppressed the response of monocytes to LPS in the presence of T mu cells, suggesting that they possess suppressor function for this response. The T gamma suppressor cells required stimulation by LPS to express their suppressor function and they exerted their suppressive effect directly on the monocyte. The existence and participation of LPS-responsive T suppressor cells on the cellular procoagulant response in vitro add a new dimension to the complexity of the rapid pathway of the collaborative cellular procoagulant response and may be important in the pathogenesis of disseminated intravascular coagulation.

The possible role of radiotherapy in chronic lymphocytic leukaemia: a critical review

The few clinical studies which have utilized irradiation as a treatment modality for chronic lymphocytic leukaemia (CLL) during the last two decades have led to rather conflicting and sometimes disappointing results. Low-dose total body irradiation (TBI) and extracorporeal, or mediastinal, radiotherapy did not appear to be superior to chemotherapy in most trials. Only the fractionated low-dose (600-800 rad) splenic irradiation was found to induce a long-lasting decrease of the lymphocyte count and a decrease in bone marrow infiltration in a significant proportion of cases, without any noticeable haematological toxicity. But new data is recently emerging; stratification of CLL in various subgroups, better understanding of the role of the normal T-cell subsets, better knowledge of the interaction between irradiation and haematopoiesis, and of the radiosensitivity of the various lymphocyte subpopulations. Thus one can now reconsider the possible role radiotherapy, and particularly splenic irradiation, can play as an alternative treatment to chemotherapy for CLL. Haematological toxicity is still limiting the use of TBI. The spleen irradiation avoids this drawback. Recent data suggest that this splenic irradiation could be efficient by means of several mechanisms; the successive destruction, fraction after fraction, of the part of the malignant lymphocyte clone present in the spleen is likely to be the main therapeutic explanation, with the knowledge that the lower the differentiation of the malignant clone, the more efficacious the irradiation. But in parallel, the destruction of the large subset of T-suppressors which is constantly present in the spleen may account for the improvement of the peripheral blood count after splenic irradiation, and possibly for a direct effect towards the malignant clone. With respect to these new data, splenic irradiation clearly needs further clinical evaluation in the treatment of CLL.

T cells in patients with chronic T gamma lymphocytosis: morphology, cytochemistry, ultrastructure and immunological characteristics

We have studied the morphology and cytochemistry in relation to the immunological phenotyping and functional properties of T cells from eight patients with chronic T gamma lymphocytosis. At the light microscopic level the morphology of the patients' lymphocytes was similar to that described for large granular lymphocytes. Ultrastructurally, a division into two groups could be made on differences in the amount of cytoplasm and the location and the more irregular form of the nuclei. The lymphocytes of one group (five patients) had in common the phenotype Fc gamma +, T3 +, T4 -, T8 +, Ia -, M1 - and demonstrated (with the exception of one patient) the same functions: presence of K-cell activity, absence of NK, helper and suppressor cell activities. In the other group (three patients), the lymphocytes of one patient showed the same phenotype and functions as those indicated above. The other two patients both lacked the T8 antigen on their lymphocytes but were different with regard to other surface markers. In addition, their cells were functionally identical: both demonstrated NK- and K-cell activity. Thus in this group of eight patients with chronic T gamma lymphocytosis, the immunological and functional subdivision paralleled in part a morphological division at the ultrastructural level.

Polymorphism of Fc receptor on murine B cells is Igh-linked

Analysis of mouse IgG binding to Fc receptors on mouse B cells indicates that the IgG1, IgG2a, and IgGb subclasses bind to the same receptor. No differences in affinity were detected among subclass or between mouse strains. This same receptor bound rat IgG with an affinity that differed between mouse strains. This polymorphism in affinity for rat IgG maps to chromosome 12 distal to the Igh locus.

Interleukin 2 production by human T lymphocytes identified by antibodies to dipeptidyl peptidase IV

T-Cell subsets identified by polyclonal and monoclonal antibodies to dipeptidyl peptidase IV (DP IV) were investigated. Analysis in a cytofluorograf revealed 63 +/- 7% positive scatter-gated T lymphocytes. DP IV-positive cells were found to be T11+, 74-81% OKT4+, and 12-19% OKT8+. DP IV-negative cells were T11+ and comprise 16-40% OKT8+, and 10-30% OKT4+ T cells. Treatment of T lymphocytes with rabbit anti-DP IV and complement as well as the presence of rabbit anti-DP IV during culture resulted in a reduction of interleukin 2 (IL-2) production. This reduction was not observed with the mouse monoclonal anti-DP IV antibody II-19-4-7. Positive enrichment of DP IV-positive lymphocytes by cell sorting revealed excellent IL-2 production of DP IV-positive cells and very poor IL-2 activity in supernatants obtained from DP IV-negative lymphocytes. Thus, DP IV may serve as cell surface marker for IL-2-producing T lymphocytes.

Thyroid autoantibody synthesis by lymphocytes from different lymphoid organs: fractionation of B cells on density gradients

Lymphocytes from thymus, blood, lymph nodes and thyroid tissue of patients with autoimmune thyroid disease have been assessed for their ability to synthesize thyroid autoantibodies spontaneously or following stimulation by Pokeweed mitogen (PWM). Blood and thymic lymphocytes synthesized IgG and microsomal or thyroglobulin antibodies of IgG class in response to PWM (and were therefore probably B-memory cells), while thyroid lymphocytes frequently secreted autoantibodies spontaneously. Lymph node lymphocytes resembled blood lymphocytes in terms of increased production of IgG in response to PWM; however, spontaneous secretion of thyroid autoantibodies was observed in some lymph node suspensions, and the magnitude of the increment in thyroid autoantibodies synthesized in response to PWM was lower than that observed for blood lymphocytes. Fractionation of B-cell enriched populations on density gradients and subsequent incubation of the fractions with T cells and PWM demonstrated that, whereas blood B cells capable of synthesizing autoantibody were found in both medium and low density fractions, lymph node precursors of thyroid autoantibody-secreting cells were associated almost exclusively with the light fractions. The presence in lymph nodes of small numbers of low density B cells, compared with a much higher proportion of the heterogeneous population capable of secreting IgG, could account for the discrepancy between the IgG and autoantibody response to PWM. Further, it seems likely that the density difference in the autoantibody precursor population of lymph nodes and blood is related to the difference in the state of activation of B cells in these lymphoid organs.

Suppression of T helper function: an immunoregulatory effect of rosette inhibitory factor in hepatitis B virus infection

The potential immunoregulatory effects of rosette inhibitory factor (RIF) were evaluated using lymphocyte subpopulations defined by monoclonal antibodies (OKT4, OKT8). Initial experiments indicated that RIF inhibits E-rosette formation by T cells that provide helper/inducer function (OKT4+). Subsequently, experiments were done to assess if RIF had an inhibitory effect on in vitro immunoglobulin and anti-HBs production. These studies used peripheral blood mononuclear cells from convalescent and hepatitis B-vaccinated donors. The results indicated that RIF-positive low-density lipoprotein, but not RIF-negative low-density lipoprotein, inhibits in vitro production of IgG and IgM by 60 to 70% and totally ablates anti-HBs synthesis. In order to determine if RIF directly affected the proliferative response of T4 lymphocytes, these cells were cultured in the presence of optimal mitogen concentrations and either RIF-positive or RIF-negative low-density lipoprotein. The experiments demonstrated that RIF-treated T4 cells are hyporesponsive to pokeweed mitogen and phytohemagglutinin when compared to T4 cells cultured in the absence of RIF. In contrast, B cell proliferation in response to soluble T helper factors was not affected by incubation with RIF. As the production of soluble helper factors by T4 cells was inhibited by exposure to RIF-positive but not RIF-negative low-density lipoprotein, we conclude that the suppressive effect of RIF on immunoglobulin and anti-HBs synthesis is due to inhibition of this specific helper T cell function.

A lymphoproliferative disorder of T gamma cells with the phenotype of cytotoxic/suppressor T-cell

A 25-yr-old Japanese male showed unique T gamma cell proliferation different from cases reported previously. His clinical and hematological features were characterized by persistent high fever and the appearance of large lymphocytes with abundant cytoplasm and azurophilic granules in the peripheral blood (11% of the leukocyte differential count) and the ascitic fluid. These lymphocytes showed the ability to bind the Fc portion of IgG and they beared the antigen of cytotoxic/suppressor T-cell defined by monoclonal antibodies. T-cells from this patient suppressed the immunoglobulin production of normal B-cells by pokeweed mitogen, although a polyclonal hypergammaglobulinemia was observed in the serum. Chromosomal abnormality indicated the malignant nature of the proliferating T gamma cells in this patient. The clinical, hematological, and immunological findings characterized the disease of this patient as a distinct entity among the lymphoproliferative disorders of T-cell origin.

Cytolytic activity of T lymphocytes isolated from ovarian carcinoma ascitic fluid. Analysis at the population and clonal level

T lymphocytes were isolated from ascitic fluid of three patients with ovarian carcinoma at III-IV stage. Surface markers analysis of such purified T cells revealed that T8+ cells were well represented among ascitic T lymphocytes (from 35 to 56%). Low percentages of activated T cells, as indicated by HLA-DR and TAC (interleukin-2 receptor) positivity, were also present. However, fresh ascitic T lymphocytes failed to lyse autologous tumor target cells in a 4-h 51Cr release assay. Furthermore, by applying a limiting dilution microculture system that allows optimal conditions for cloning of human T lymphocytes, we derived clones from these populations. From 41 to 63% of clones so obtained had cytolytic activity in a lectin-dependent assay allowing detection of cytolytic T cells of any specificity. More importantly, in all three patients several clones were found to lyse autologous tumor target cells as well. Some of these clones have been studied in more detail: 9 out of 10 expressed the T8+/T4- phenotype, whereas only one was T8-/T4+; 6 out of 9 clones had a definite NK-like activity, while none of them lysed autologous PHA-lymphoblasts.

Impaired B lymphocyte reactivity in patients after radiotherapy

The effect of therapeutic irradiation upon B lymphocyte function was investigated in patients with various malignancies. The test system used was a reverse hemolytic plaque assay, which made it possible to study the activation and differentiation of B lymphocytes into immunoglobulin-secreting cells (ISC). Peripheral blood lymphocytes from normal individuals and patients before and after radiotherapy were stimulated in vitro with the polyclonal B cell activator pokeweed mitogen, and the number of ISC was estimated. B cell reactivity was markedly reduced in those patients who had received irradiation within the last six months. In patients in whom radiotherapy had been terminated more than 12 months before the lymphocytes were tested, B cell reactivity was comparable to that of patients prior to radiotherapy. By means of marker analyses, there was a reduction of B lymphocytes and T lymphocytes in the peripheral blood with a preponderance of T helper cells. Several mechanisms--e.g., reduced or defective B cell differentiation, altered regulatory T-helper or suppressor cell function or activation of suppressive monocytes--could be responsible for impaired B cell reactivity after radiotherapy.

Atopic asthma: T lymphocyte subpopulations

Atopy is associated with diminished cell-mediated immunity and increased amounts of IgE, both of which may be caused by imbalances of T lymphocyte subsets. We compared the composition of highly purified peripheral-blood T cells of fifteen atopic asthmatics with ten non-atopic control subjects. Each subject was examined on five separate occasions. Indirect immunofluorescence using monoclonal antibodies was used to define T cell subsets. We examined the proportion of T cells with T3 (most T cells), T4 (helper/inducer), T8 (suppressor/cytotoxic), M1 (natural killer), and Ia (activated T cells) surface antigens. Blood was obtained at the same time of day to eliminate the effects of circadian rhythm. Subjects were taking no medications. We found no difference between the groups of the percentage of T cells with T4, T8, M1, and Ia antigens, nor the ratio of T4+ (helper) to T8+ (suppressor) cells. T3 percent was slightly (94.3 vs 92.5%) higher in the atopic group. We conclude that atopic asthma is not associated with imbalances of peripheral-blood T cell subsets.

Impaired suppressor activity in children affected by coeliac disease

Immunoregulatory cells were enumerated in 19 coeliac disease children on a gluten free diet by means of monoclonal antibodies that define total T lymphocytes (T3), helper/inducer T cells (T4), suppressor/cytotoxic T cells (T8) and monocytes (M1), as well as by means of surface receptors for Fc fragments of IgM and IgG (T mu and T gamma, respectively). In addition, suppressor cell function was assessed in 17 coeliac disease patients by examining the ability of concanavalin-A (Con-A)-activated suppressor cells to inhibit autologous cell response to mitogenic stimulus as compared with age-matched controls. No statistically significant differences were found in the percentages of subsets defined by monoclonal antibodies between coeliac disease patients and age-matched controls, whereas coeliac disease patients had a significant decrease of the subpopulation bearing membrane receptor for Fc fragment of IgG. Mean value was 8.5% in coeliac patients versus 13.4% in age-matched controls. In the functional assay, mononuclear cells from 10 out of 17 coeliac disease patients either totally or partially failed to suppress responder cells after Con-A-activation. This defect is not related to HLA-DR status, because no difference was found between patients-HLA-matched and unmatched normal individuals. In this assay, mononuclear cells of three coeliac disease patients with low suppressor activity were able to inhibit responder cells to the same extent as controls, when indomethacin was used to block prostaglandin production in the induction phase of Con-A-activated suppressor cells. Our results suggest that an abnormality in immunoregulation may play a role in the pathogenesis of coeliac disease.

The effect of 2'deoxyguanosine on human lymphocyte responses. II. 2'deoxyguanosine enhances PWM-induced B cell differentiation

Addition of 40 microM 2'deoxyguanosine (2'd Guo) results in enhancement of human lymphocyte cultures stimulated with pokeweed mitogen, assessed by staining intracytoplasmic immunoglobulins. Furthermore, B cell responses were enhanced under experimental conditions favouring T cell suppression rather than help. Experiments with enriched B cell fractions indicate that 2'dGuo does not directly stimulate B cell responses. The enhancement by 2'dGuo was still observed in the presence of irradiated (non-proliferating) T cells. The mechanism of enhancement by 2'dGuo is discussed in terms of its effect on proliferation-independent suppressor T cells.

T-cell abnormalities after mediastinal irradiation for lung cancer. The in vitro influence of synthetic thymosin alpha-1

The effects of mediastinal irradiation (RT) on the numbers and functions of purified peripheral blood T-lymphocytes from patients with locally advanced non-small cell lung cancer were evaluated. The patients were candidates for a randomized trial to evaluate the immunorestorative properties of synthetic thymosin alpha-1. Twenty-one patients studied before RT did not exhibit any significant difference in T-cell numbers or function compared to age-matched healthy subjects. However, 41 patients studied within 1 week after completing RT exhibited significant depressions of E-rosette-forming cells at 4 degrees C (E4 degrees-RFC)/mm3, E-rosette-forming cells at 29 degrees C (E29 degrees-RFC)/mm3, OKT3/mm3, OKT4/mm3, and OKT8/mm3 (P = 0.0001); total T-cell percentages (%OKT3, P = 0.01); and T-cell proliferative responses in mixed lymphocyte cultures (MLR) (P = 0.01) and to the mitogen phytohemagglutinin under suboptimal conditions (P less than or equal to 0.03). Nine patients studied before and after RT showed a significant increase in OKT4/OKT8 (P = 0.01) following RT. A short-term in vitro incubation with thymosin alpha-1 could enhance MLR of T-cells in 12 of 27 patients with post-RT abnormalities. In 13 patients who were treated with placebo, the RT-induced depression of T-cell numbers and function persisted for at least 3 to 4 months. In addition, in 12 patients progressive decreases developed in %E4 degrees-RFC, %OKT3, %OKT4, and OKT4/OKT8, which always preceded clinical relapse. This study indicates that mediastinal RT results in prolonged depletion of circulating T-cells, alterations of T-cell subset proportions, and intrinsic T-cell functional deficiencies. This patient population provides a uniformly immunosuppressed group of subjects with which to evaluate the immunorestorative effects of thymosin alpha-1 or other biologic response modifiers.

Differential effects of experimental hyperlipidemia on various types of rabbit peripheral blood lymphocyte receptors

Rabbits fed a high-cholesterol diet for 3 months showed an increase in peripheral blood lymphocytes with membrane receptors for the Fc portion of immunoglobulin G and a decrease in lymphocytes with receptors for the Fc portion of immunoglobulin M and also with receptors for the third component of the complement. Thus our results indicate changes in lymphocyte membrane receptor expression in experimental hyperlipidemia that may supposedly influence some lymphocyte functions.

B cell growth factor activity of immunoaffinity-purified and recombinant human interleukin 2

We investigated the effect of recombinant and affinity-purified human interleukin 2 (IL2) on human B cell proliferation. Five X 10(4) nonadherent spleen cells that had been depleted twice of T cells were activated by 3-day culture with formaldehyde-killed Staphylococcus aureus Cowan strain I (SAC) prior to addition of tested growth factors. Cultures were harvested 72 h later. It was found that both IL2 preparations led to optimal cell proliferation compared with a control supernatant obtained by 36 h phytohemagglutinin stimulation of spleen mononuclear cells. Moreover, the effect of such spleen supernatant on B cell proliferation correlated with the IL2 activity since its B cell growth factor activity (BCGF) was not greater than that of purified IL2 and no residual BCGF activity could be detected after absorption of all IL2 activity by the IL2-dependent cytotoxic T lymphocyte line cells. T cells, enumerated as E-rosetting cells as well as T3+ cells, represented 0.2 to 2% of the cells recovered at termination of the cultures (day 6) and there were less than 1% E-rosetting cells in freshly purified or SAC-activated (day 3) B cell populations. Therefore, we conclude that IL2 is a growth factor not only for activated T cells but also for activated human B cells.

Alteration of Fc-receptor phenotype and proliferative capacity of Fc-IgG-receptor positive lymphocytes through interaction with soluble immune complexes of patients with SLE or RA

Soluble circulating immune complexes (CIC) are a common finding in patients with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) or other autoimmune diseases. The predominant immunoglobulin class of most CIC is IgG, which enables these CIC to bind to Fc-IgG-receptor expressing cells. In this study the interaction between soluble CIC from patients with SLE or RA and Fc-IgG-receptor positive lymphoid cells from healthy individuals was investigated. Similar to the effect observed with insoluble immune complexes, soluble CIC interact with Fc-IgG-receptor positive lymphoid cells and can induce a modulation of Fc-receptor expression. Fc-IgG-receptors are lost and Fc-IgM-receptors are expressed on the same cells after IC interaction and culturing the cells for 24 h. Simultaneously with this change of Fc-receptor phenotype the originally Fc-IgG-receptor positive cells demonstrate a decreased ability to proliferate upon mitogen stimulation. This change of phenotype and proliferative capacity correlates with the content of CIC in the sera of patients with SLE or RA.

Glucocorticoids enhance the in vitro Ig synthesis of pokeweed mitogen-stimulated human B cells by inhibiting the suppressive effect of T8+ T cells

The in vitro effects of three potent glucocorticoids (GC) (dexamethasone, prednisolone, cortisone) on human lymphocyte functions were investigated. In pharmacological concentrations GC strongly suppressed lymphocyte transformation induced by T-cell mitogen (concanavalin A and phytohaemagglutinin). After pokeweed mitogen (PWM) stimulation GC enhanced the number of immunoglobulin (Ig)-producing cells without affecting the proliferative response. Mineralocorticoid aldosterone showed no effect. Addition of 3 X 10(-8)-3 X 10(-6) mol/l of different GC to PWM cultures significantly increased the number of Ig-secreting cells, measured by the plaque-forming cell assay. Experiments conducted with fractionated defined lymphocyte subpopulations showed that the T8+, a radiosensitive T suppressor cell, is more sensitive than the T4+ T helper cell to GC effects. It is concluded that GC in pharmacological concentrations display a dual effect on human lymphocyte functions in vitro: an inhibition of lectin-induced T lymphocyte proliferation and a rather selective inhibition of T suppressor cell function which leads to an enhanced B-cell maturation and Ig synthesis in PWM-stimulated cultures. No measurable direct effect on the B lymphocytes was noticed.

Characteristics of histamine receptors present on suppressor T cells in "healthy individuals"

Twelve to 30% histamine receptor bearing cells were detectable in the peripheral blood mononuclear cells of healthy tuberculin sensitive individuals. The number of binding sites per cell ranged from 2.1 X 10(4) to 5.08 X 10(4) (mean 2.5 X 10(4)) with an affinity ranging from 2.5 X 10(-6) M to 10.9 X 10(-6) M (mean 3.6 X 10(-6) M). The histamine receptors on these cells were found to be of H2 type as indicated by the abrogation of binding of 3H-histamine by cimetidine. It was further confirmed that histamine receptor bearing cells in the peripheral blood belonged to a T cell subset which formed rosettes with AET treated sheep erythrocytes and had receptors for Fc portion of IgG and phenotype markers of T3 and T8. Deletion of such cells by means of affinity chromatography on histamine bound Sepharose columns, led to enhanced antigen induced lymphoproliferation indicating the suppressor nature of these T cells.

Rosette formation between T and autologous B lymphocytes. I. Characterization of a T cell subpopulation

The ability of some T cells to form rosettes with autologous B lymphocytes (TrB cells) appears to be a marker of a subpopulation of T cells, a majority of which have high avidity receptors for sheep red blood cells. TrB cells have a higher proportion of suppressor cell surface markers (OKT-8+ and receptor for the Fc fraction of IgG), as well as higher suppressor activity than other T cell populations. TrB cells also help in B lymphocyte transformation under the stimulation of a T-dependent B mitogen. The TrB cells seem to express the Fc gamma receptor after ecotatic association with B cells, since T gamma cells previously isolated from total T cells form rosettes with B cells in the same proportion in which total T cells do. Studies on TrB cells subpopulation may explain some of the defects in functional cell-cell interactions.

Phenotypic and functional heterogeneity of human T cell clones producing gamma-interferon

Human T cell clones were derived from peripheral blood and screened for their ability to release gamma-interferon (gamma-IF) following PHA stimulation. Nine clones producing more than 20 U/ml of gamma-IF were expanded and analyzed for cytolytic activity in a lectin-dependent assay and for the ability to release interleukin-2 (IL-2). In addition, clones were analyzed for T4 and T8 antigen expression. Five out of nine clones had cytolytic T lymphocyte activity, while four released relatively large amounts of IL-2. Five clones were T4+ while the remaining expressed the T8+ phenotype. These results clearly indicate that gamma-IF production is not restricted to T cell subsets defined according to either functional or phenotypic criteria.

Lymphocyte subsets in patients with compositae oleoresin dermatitis and increased UVA sensitivity during treatment with azathioprine

Four patients with severe contact dermatitis resulting from compositae oleoresin were found to have increased sensitivity to ultraviolet light. All showed a clear reduction of Leu-3a-positive lymphocytes (T helper/inducer cells) and cells expressing the Ia phenotype in their blood. The numbers of T suppressor/cytotoxic (Leu 2a) lymphocytes, monocytes and B lymphocytes were within the normal range. Treatment with azathioprine (150 mg daily) improved the eczema. The number of Leu-3a-positive lymphocytes normalized during therapy, but the number of Ia-positive cells did not.

Melphalan treatment of human peripheral T cells promotes Ig production by B cells in vitro

Human blood B lymphocytes were cocultured with autologous T lymphocytes which were pretested with melphalan or adriamycin in the presence of pokeweed mitogen (PWM). Melphalan treatment of the cells produced an increased secretion of IgG and IgM, whereas adriamycin did not.

IgE Fc receptor positive T and B lymphocytes in patients with the hyper IgE syndrome

The percentages of peripheral blood lymphocytes (PBL), bearing Fc receptors for IgE (Fc epsilon R) and IgG (Fc gamma R) were determined in four patients with the hyper IgE syndrome by a rosette assay employing IgE and IgG coated fixed ox erythrocytes. The patients had 8 +/- 3% Fc epsilon R+ and 13 +/- 8% Fc gamma R+ PBL, compared to 1.2 +/- 1% Fc epsilon R+ and 17 +/- 4% Fc gamma R+ PBL for control donors. T cells were isolated by rosetting with neuraminidase treated sheep erythrocytes (EN). Indirect immunofluorescence with Lyt 3 monoclonal antibody (MoAb) to the sheep erythrocyte receptor, followed by rosetting for Fc epsilon R and Fc gamma R showed that the patients' T cells contained less than 0.1% Fc epsilon R+ and 1.4 +/- 0.2% Fc gamma R+ cells; T cells from the control subjects contained less than 0.1% Fc epsilon R+ and 11 +/- 4% Fc gamma R+ cells. The non-T (EN rosette depleted) cells of the patients included 56 +/- 18% sIgM+/sIgD+, 45 +/- 9% Fc epsilon R+ and 35 +/- 27% Fc gamma R+ cells. Indirect immunofluorescence with MoAb to IgM, IgD, and NK cells (antibody B73.1) followed by rosetting for Fc epsilon R and Fc gamma R, indicated that 92 +/- 2% of the Fc epsilon R+ cells and 9 +/- 7% of the Fc gamma R+ cells were B cells (mu+/delta+), while 3 +/- 4% of the Fc epsilon R+ and 30 +/- 23% of the Fc gamma R+ cells were NK cells (B73.1+). Thus, most of the Fc epsilon R+ non-T cells were B cells, and only a small fraction appeared to be NK cells. On the other hand, Fc gamma R+ B cells were outnumbered by Fc gamma R+ NK cells (B73.1+) by three to one. The data indicate that patients with the hyper IgE syndrome have increased numbers of Fc gamma R+ PBL, most of them being B cells, whereas their T cells contain less than 0.1% Fc epsilon R+ cells.

Release of hemopoietic factors by normal human T cell lines with either suppressor or helper activity

We analyzed the release of activities capable of stimulating the in vitro growth of human hemopoietic progenitor cells by long-term cultured T cell growth factor (TCGF)-dependent human T lymphocytes. Seven cell lines tested produced colony-stimulating activity (CSA) as well as burst-promoting activity (BPA). The CSA stimulated primarily the growth of the cells forming colonies after 14 days of incubation. In addition the supernatants from these seven T-cell lines showed the ability to induce the in vitro growth of mixed granulocyte, erythroid, megakaryocyte, macrophage colonies (CFU-GEMM). The release of hemopoietic factors did not depend on the presence of accessory cells or phytohemagglutinin or serum during the incubation for factor production. In six of the T cell lines the majority of the cells were reactive to the OKT 8 monoclonal antibody (MoAb), whereas one cell line contained mostly OKT 4+ cells. Suppressor activity was detected in three tested OKT 8+ cell lines, while the one OKT 4+ displayed helper activity. All cell lines produced hemopoietic factors with equal efficiency. These results indicate that factors affecting human hematopoiesis are produced by normal T lymphocytes in long-term culture and this property is not related to the helper or suppressor activity of the cultured cells.