Monoclonal antibody analysis of responder and stimulator cells in the human autologous mixed lymphocyte reaction

Responder and stimulator cell subpopulations in the autologous mixed lymphocyte reaction (AMLR) were determined with the OK series of monoclonal antibodies. Mitomycin-C-treated, monocyte-enriched cell populations were used as stimulator cells in the AMLR. Treatment of these monocytes with either OKM and/or OKI monoclonal antibodies and complement resulted in a marked loss of ability of these cells to act as stimulators in the AMLR. Removal of OKT3+ and OKT4+ cells diminished the proliferative responses of AMLR cultures. Interaction of T cells with autologous monocytes resulted in generation of cells capable of suppressing both MLR and AMLR cultures. The suppressor activity of these cells was diminished by treatment with OKI , OKT4 or OKT8 monoclonal antibodies. No cytotoxic activity to autologous or allogeneic monocytes was observed. Additional studies showed an increased number of OKT9 + and OKI + as well as OKT8+ T cells in the AMLR responder cell population. This study indicates that cultures of T lymphocytes with autologous monocytes yield T cell subset(s) which suppress MLR and AMLR reactivity.     

Activation of immune regulatory circuits among OKT4+ cells by autologous mixed lymphocyte reactions

We examined the nature of an autologous mixed lymphocyte reaction (AMLR) using T cell subsets defined by monoclonal antibodies. Cells capable of proliferating in the AMLR were demonstrated to reside in an OKT4+, but not an OKT8+, cell subset. With regard to the role of the T cell subsets recoverable from AMLR in the immune regulation, OKT4+ cells isolated from cells that had been activated for 3 days in AMLR did help pokeweed mitogen (PWM) stimulated immunoglobulin synthesis by autologous B cells. However, the OKT4+ cells activated for 6 days in AMLR exerted strong suppressor activity for PWM-induced immunoglobulin synthesis. Irradiation with 1,500 rad on activated OKT4+ cells in AMLR for 6 days not only eliminated the suppressor function but allowed for re-emergence of helper function. Cells exerting suppressor activity alone were recovered from OKT8+ cells stimulated with or without autologous non-T cells. These data suggest that OKT4+ cells activated in AMLR contain two functionally different subsets; one as helper cells and the other as suppressor cells. In addition, the emergence of OKT4+ suppressor function follows activation of the OKT4+ helper population, suggesting that a part of AMLR reflects a mechanism of 'feedback suppression' among OKT4+ cells.     

Radiosensitivity of isolated subsets of human lymphocytes (E+, OKT4+, OKT8+): protective role of monocytes and monokines.

The sensitivity of human peripheral blood T lymphoid populations to 60Co ionizing radiation was investigated. Dose-response values were determined for populations that are commonly identified by their ability to form spontaneous rosettes with sheep red blood cells (E+ cells), helper T lymphocytes (OKT4+ cells) and suppressor T lymphocytes (OKT8+ cells). OKT4+ and OKT8+ T cell subsets were negatively selected by complement (C)-mediated cytolysis using the C fixing OKT4 and OKT8 monoclonal antibodies (MoAb). The irradiation-induced damage was assessed by the lymphoblast transformation test, using the polyclonal T cell mitogen, phytohaemagglutinin (PHA) and the OKT3 MoAb. (The OKT3 antibodies are mitogenic for T cells only in the presence of monocytes). No significant differences were evident between dose-response values of E+, OKT4+ and OKT8+ lymphoid subpopulations when using PHA as a mitogen. On the other hand, when OKT3 was used to trigger resting irradiated peripheral blood T lymphocytes, e.g. E+ cells, OKT3 stimulated T cells proved to be markedly radioresistant as compared to PHA stimulated cell cultures. This was found to result from the fact that purified T cell cultures were co-cultured with non-irradiated monocytes when OKT3 was employed as a motogen. Similarly co-culturing of irradiated E+, OKT4+ and OKT8+ cells with non-irradiated autologus monocytes partially corrected the irradiation damage, regardless of the mitogen employed. More important, however, was the observation that macrophage derived supernatants containing (interleukin-1) IL-1 could confer a high degree of radioprotection on irradiated E+ cells. It is concluded that monocytes and monocyte products partially protect against irradiation damage.     

Activation of OKT4 suppressor cells in the autologous mixed lymphocyte reaction of patients with juvenile rheumatoid arthritis.

Activation of suppressor cells by the autologous mixed lymphocyte reaction (AMLR) was studied in patients with juvenile rheumatoid arthritis (JRA). Isolated OKT4 cells were used as responders and irradiated whole non-T cell preparations, non-adherent non-T cells (B and null cells), adherent non-T cells (monocytes), and B cells preactivated by Staphylococcus aureus Cowan I, as stimulators in the AMLR. Suppression was assessed by a reduction of pokeweed mitogen stimulated immunoglobulin synthesis by lymphocytes of healthy donors upon addition of AMLR-activated OKT4 cells. The results of this study suggest normal activation of OKT4 suppressor cells in the AMLR of patients with JRA.     

Comparison of phorbol myristate acetate and phytohaemagglutinin as stimulators of in vitro T lymphocyte colony formation of human peripheral blood lymphocytes. I. Surface markers of colony cells.

Human T lymphocyte colonies were grown in methylcellulose semi-solid cultures in the presence of phytohaemagglutinin (PHA) and/or phorbol myristate acetate (PMA). Surface marker analysis showed lower percentages of OKT3- and OKT4-positive cells in PMA-induced colonies than those in PHA-induced colonies. The percentage of OKIa1-positive cells in PMA-induced colonies was approximately twice that in PHA-induced colonies. The percentage of OKT9-positive cells in PMA-induced colonies was significantly lower than that in PHA-induced colonies. These data suggest that the subsets of PMA-induced colony cells express a more immature phenotype than that of PHA-induced colony cells and that, among PMA-induced colony cells, there are fewer T cells in the proliferative status at the time tested. When 3 X 10(5)/ml monocyte-depleted T cells, at which concentration of seeded cells neither PHA nor PMA could induce colony growth, were cultured in the presence of both PHA and PMA, T cell colony growth was observed. In T cell colonies induced by a combination of PHA and PMA, the percentages of OKT3-, OKT4- and OKT8-positive cells were different from those in colonies induced by either PHA or PMA alone. These results suggest that PMA acts not only as a substitute for monocytes and/or interleukin-1, but may directly affect lymphocyte proliferation induced by a combination of PHA and PMA.     

Effect of PHA-activated T cells on B-cell differentiation.

Recent studies indicate that human T cells expressing the T4 determinant are comprised of functionally distinct subsets. We investigated if activation of OKT4+ cells with the mitogen PHA affected their ability to regulate the proliferation and polyclonal differentiation of autologous B cells. OKT4+ cells were preactivated with PHA and then cocultured with autologous B cells in the presence or absence of PWM. B-cell proliferation and differentiation to immunoglobulin-secreting cells (IgSC) were assessed by [3H]thymidine incorporation and reverse haemolytic plaque assay, respectively. In the absence of PWM, the PHA-activated OKT4+ cells demonstrated radioresistant help and radiosensitive suppression of IgSC responses. Addition of PWM to cocultures of irradiated PHA preactivated OKT4 cells and autologous B cells resulted in further suppression of IgSC responses, suggesting that PWM activated yet another suppression mechanism. Addition of PWM caused diminished B-cell proliferation as well. These data demonstrate functional heterogeneity within the OKT4 subset, and suggest that the particular immunoregulatory activity displayed is influenced by the state and mode of activation of these cells.     

The suppressive effects of monocytes in the autologous mixed lymphocyte reaction.

The response of isolated T cells to autologous non-T mononuclear cells is called the autologous mixed lymphocyte reaction (AMLR). The responding T cells show immunological memory and specificity. This reaction was present in all thirty normal individuals tested. Since the AMLR in the absence of evidence of in vivo excessive lymphoproliferation must somehow be controlled, we have studied the interactions of enriched T cells, B cells and monocytes in culture as possible means of regulation of this reaction. Increased rate of [3H] thymidine incorporation by T lymphocytes were observed when they were cultured with mitomycin-treated autologous non-T cells. This was increased when the stimulating cells were enriched for B lymphocytes and was significantly decreased when the stimulating cells were enriched for monocytes. Addition of monocyte-enriched cells to B-enriched cells in a 1:1 ratio, significantly suppressed the AMLR (P- less than 0.01). Equivalent numbers of monocytes did not suppress T-cell responses to phytohaemagglutinin (PHA). Monocyte-enriched cells were separated from stimulating B-enriched cells by nucleopore (0.6 mu) or dialysis tubing (0.12 mu) in Marbrook chambers. Soluble products released from monocyte-enriched cells also suppressed the AMLR. The significance of the AMLR in vivo is uncertain but it may be important in immunoregulation, monocytes playing an important role.     

Autologous Mixed Lymphocyte Reaction in Man

Human peripheral T cells and T-cell Subpopulations defined with monoclonal antibodies of the OKT series were studied for the proliferative response on stimulation with autologous non-T cells or mitogen-activated T cells as stimulators in autologous mixed lymphocyte reaction (AMLR). T cells exhibited a vigorous proliferative response when stimulated with autologous non-T cells or activated T cells but not with unactivated T cells. The stimulatory capacity of non-T cells or activated T cells in AMLR was inhibited by prior treatment of stimulator cells with 7, 2 anti-human Ia framework-specific monoclonal antibody in the absence of complement. A BUdR and light technique was used to ablate proliferating T cells in response to either non-T cells or activated T cells in AMLR. The removal of T cells responding to autologous non-T cells left the responsiveness to autologous activated T cells relatively intact. Conversely, the removal of T cells responding to autologous activated T cells left the responsiveness 10 autologous non-T cells relatively intact. Thus T cells responding to autologous non-T cells appear to be distinct from those responding to autologous activated T cells in AMLR. Further analysis with OKT4 and OKT8 monoclonal antibodies showed that the major population responding to autologous non-T cells was contained in OKT4⁺ T cells and that responding to autologous activated-T cells was contained in OKT8⁺ T-cell subset. However, both OKT4⁺ and OKT8⁺ T-cell subsets responded by proliferation to non-T cells and activated T cells in allogeneic MLR. T cells selected after AMLR between T and non-T cells or T and activated T cells were treated with mitomycin and examined for their regulatory influence on the proliferative response of fresh autologous responder T cells. T cells selected from T and non-T AMLR augmented and those obtained from T and activated T AMLR suppressed the proliferative responses of fresh autologous T cells to phytohaemagglutinin and to autologous or allogeneic non-T cells in AMLR or allogeneic MLR. These findings indicate that in AMLR between T and non-T cells or T and activated T cells phenotypically distinct Subpopulations of T lymphocytes respond by proliferation and express distinct immunoregulatory functions.     

Surface markers of cloned human T cells with helper or suppressor activity on pokeweed mitogen-driven B cell differentiation

Human spleen T cells stimulated with pokeweed mitogen (PWM) were cloned under limiting conditions in microculture systems using interleukin 2 and irradiated autologous cells. Clones were screened for helper or suppressor activity on PWM-dependent B cell differentiation by adding cell aliquots to either isolated B cells and PWM or to mixtures of T and B cells and PWM. Out of 97 clones tested, 14 promoted intense B cell differentiation, as assessed by measurements of secreted IgG, and 6 strongly inhibited B cell maturation induced by spleen T cells. All the selected clones maintained their original activity after short-term clonal expansion; in addition, a similar (helper or suppressor) effect was detected when the total number of plasma cells per well was evaluated. Suppressor clones had no cytolytic activity on autologous T and B cell blasts, K562 cells or antibody-coated L 1210 mouse cells. Nine helper and 6 suppressor clones were analyzed for a battery of surface markers. All the clones were E rosette-positive and expressed HLA-DR (Ia) antigens. Fcmu receptor was present on a single helper clone, whereas Fc gamma receptor was expressed on a suppressor clone only. All but two clones expressed the OKT4+/ OKT8-, a single suppressor clone was OKT8+/OKT4-, whereas coexpression of OKT4 and OKT8 antigens was detected in one helper clone. Thus, the claim that helper T cells are OKT4+/OKT8- and suppressor T cells are OKT4-/OKT8+ is not supported by the analysis of their phenotype at the clonal level.     

Autologous and allogeneic mixed-lymphocyte responses following thermal injury in man: the immunomodulatory effects of interleukin 1, interleukin 2, and a prostaglandin inhibitor, WY-18251

A group of 30 burn patients with 36-87% total body surface area (TBSA) burns was studied at 24-48 hr postburn. These included studies of (1) autologous and allogeneic mixed-lymphocyte reactions (MLR); (2) the immunoregulatory influence of mitomycin C-treated T cells, non-T cells, and unfractionated peripheral blood lymphocytes (PBL) on allogeneic MLR; and (3) correlation between the proportions of T-cell subsets defined with monoclonal antibodies (OKT4 and OKT8) and autologous MLR. Studies concerning adherent cell production of thromboxane, prostaglandin E2, and prostaglandin F2a and the immunomodulatory effects of Interleukin 1 (IL-1), Interleukin 2 (IL-2), and a prostaglandin inhibitor, WY-18251, on autologous MLR are presented. The autologous mixed-lymphocyte reaction was depressed in 60% of the burn patients tested. This depressed response correlated closely to the extent of third-degree injury (P less than 0.025) and to TBSA injury greater than 60% (P less than 0.025). A linear correlation was observed between the depression in autologous MLR and a decrease in both the percentage of OKT4+ T cells and the OKT4+/OKT8+ ratio. The response of T cells from burn patients in allogeneic MLR was normal. Age, sex, TBSA of the burn, and size of second-degree burn did not correlate with the abnormalities observed in MLR. Mitomycin C-treated mononuclear cells, purified T cells, or non-T cells from burned patients did not demonstrate any suppressive influence on MLR in normals. Monocyte number and arachidonic acid metabolism were investigated. In addition to increased numbers of monocytes following thermal injury, adherent cells produced increased quantities of thromboxane, prostaglandin E2, and prostaglandin F2a. The effects of Interleukin 1, Interleukin 2, and a prostaglandin inhibitor, WY-18251, were studied in autologous MLR (AMLR) of burned and normal patients. Interleukin 1 and WY-18251 did not induce any significant changes in proliferation in burned patients or normal controls. When compared to cultures without exogenous IL-2, an increase in AMLR was observed following the addition of IL-2 to burn patient cultures at Day 6 and Day 7 of culture. Although the addition of IL-2 did increase proliferation in AMLR of normal controls at Day 6 and Day 7, the enhancement observed for the burn patient cultures represented a restoration to the level of normal control cultures without IL-2. A dose-dependent increase in AMLR was observed in T cells isolated from normal and burned patients in the presence of purified Interleukin 2.(ABSTRACT TRUNCATED AT 400 WORDS)     

Human autologous mixed lymphocyte reaction as an in vitro model for autoreactivity to apoptotic antigens

Recent studies have indicated that cells undergoing apoptosis are the source of autoantigens which drive autoimmune responses in systemic lupus erythematosus (SLE). It has been recognized for many years that in vitro stimulation of T cells with irradiated major histocompatibility complex (MHC) class II-bearing autologous cells results in T-cell proliferation with immunological specificity and memory, namely the autologous mixed lymphocyte reaction (AMLR). The nature of the major stimulants in the AMLR is still unclear. We investigated whether apoptotic fragments from irradiated cells act as antigenic stimulators for AMLR or nucleohistone-primed T cells. T-cell proliferation in the primary AMLR was significantly suppressed by the presence of a caspase inhibitor Z-Val-Ala-Asp-CH2F (Z-VAD.fmk), indicating that apoptotic antigens released from irradiated autologous feeder cells act as stimulators of AMLR T cells. This inhibitory effect of Z-VAD was not caused by toxic effects, because the T-cell response to the mitogen phytohaemagglutinin (PHA) was not inhibited by Z-VAD. A nucleohistone preparation was shown to contain antigens that are important in the AMLR, as culture with nucleohistone (but not with thyroglobulin or hen-egg lysozyme) primed T cells to respond with secondary kinetics in a subsequent AMLR that was also suppressed by Z-VAD. Our data provide evidence that the AMLR constitutes a model for the evaluation of cellular and molecular mechanisms that may be relevant to the pathogenesis of SLE and similar autoimmune diseases.     

Antigenic heterogeneity of a human melanoma tumor detected by autologous CTL clones

Peripheral blood lymphocytes from a melanoma patient were stimulated with autologous melanoma cells in mixed lymphocyte tumor cultures (MLTC). After three restimulations, the lytic activity of the responder cells directed against the autologous melanoma cells was higher than that against K-562 and autologous Epstein-Barr virus-transformed B cell line (EBV-B) cells. From these MLTC-responder cells, we derived specific cytolytic T cell (CTL) clones that lysed the autologous melanoma cells and did not lyse K-562 or autologous EBV-B cells. Autologous melanoma clones were found that were resistant to some or all of these CTL clones. The autologous CTL clones recognized at least two different antigens (A, B) on the melanoma cells and three types of melanoma clones could be distinguished (A+B+, A+B-, A-B-). This antigenic heterogeneity of melanoma clones was confirmed by testing the CTL clones in cold target competition and also in antigen-dependent CTL proliferation assays performed with very small numbers of stimulator cells. The data further indicated an instability of the expression of a melanoma-associated antigen in the course of a long culture period. Among the melanoma clones that expressed antigen A, one was found to stimulate the proliferation of anti-A CTL clones much more effectively than the others. This represents a new type of heterogeneity among tumor cells which may be of significance for the elicitation of an autologous anti-tumoral immune response.     

Monocytes control gamma/delta T-cell responses by a secreted product.

Gamma-irradiated ex vivo bovine monocytes induce proliferation of gamma/delta T cells in the autologous mixed lymphocyte reaction (AMLR), whereas when not irradiated they prevent this response. In contrast, non-irradiated autologous monocytes have no effect on bovine alpha/beta T-cell proliferation in the allogenic MLR suggesting that the regulation is specific for gamma/delta T-cell responses. Here, we showed that the inhibition was not mediated by inducing cell death and that the ability of ex vivo monocytes to prevent proliferation of gamma/delta T cells was not generalized in that gamma/delta T cells still responded to mitogenic stimulation. Inhibition of the AMLR by non-irradiated monocytes could not be overcome by addition of interleukin-2 to the cultures or by costimulation with antibodies to WC1, a gamma/delta T-cell-specific cell-surface differentiation antigen shown elsewhere by us to be involved in activation of gamma/delta T cells. Furthermore, we showed that monocytes inhibited gamma/delta T-cell responses via a soluble product since inhibition occurred even when monocytes and gamma/delta T cells were separated by membranes of transwells or when supernatants from monocyte cultures were added to AMLR cultures. Maximal secretion of the inhibitory product by the monocytes occurred during the first 6 hr of in vitro culture at 37 degrees, rapidly decreased thereafter, and did not occur when monocytes were incubated at 4 degrees. The inhibition was not attributable to nitric oxide, reactive oxygen intermediates, prostaglandin E2 or transforming growth factor-beta (TGF-beta) but the ability of monocyte supernatants to mediate inhibition was sensitive to heating at 65 degrees. Lipopolysaccharide and granulocyte-macrophage colony-stimulating factor activation of monocytes temporarily abrogated their ability to inhibit proliferation. In contrast, heat-shocking had no effect on their ability to inhibit. We hypothesize that non-irradiated monocytes produce the inhibitory material in vivo in order to regulate gamma/delta T-cell responses to self-derived monocyte membrane components, but that when monocytes are altered by infection, transformation, irradiation, or cytokine activation, production of the inhibitor is temporarily suspended allowing stimulation of gamma/delta T cells to occur.     

Autologous mixed lymphocyte reaction in man. XIII. Characterization of the T-T autologous mixed lymphocyte reaction

In this study we have demonstrated that in the T-TA autologous mixed lymphocyte reaction (AMLR), OKT4⁺ T cells are the major responders; however, in the presence of additional interleukin-2 (IL-2), OKT8⁺ T cells also respond by proliferation. Both OKT4⁺ and OKT8⁺ T cells, activated in the T-non-T AMLR, act as stimulators in the T-TA AMLR. OKT4⁺ T cells activated in the T-TA AMLR suppress the proliferative response of the fresh T-non-T AMLR; control OKT4⁺ cells show no immunoregulatory activity in this system. In contrast, control OKT8⁺ T cells spontaneously suppress the proliferation of the T-non-T AMLR, but activation of OKT8⁺ T cells in the T-TA AMLR does not result in a further increase in the suppressor activity of OKT8⁺ T cells. In summary, in the T-non-T and T-TA AMLR phenotypically similar T-cell subpopulations proliferate but express distinct immunoregulatory functions and perhaps regulate the tempo of the AMLR.     

Cellular interactions in spontaneous or autologous cell-induced proliferative and lymphokine responses of human lymphocytes.

Purified human B cells were activated in cultures in the absence of any intentional stimulants as judged by lymphokine synthesis and proliferation. These responses were not augmented by monocytes. Lymphokine production (LIF) was increased in the presence of T cells. Autologous mixed lymphocyte reaction of T cells against B cells (AMLR) did not include LIF production in spite of the proliferative response. We would suggest that activated B cells present in the population of purified B cells are the stimulators in AMLR. In our interpretation these results support the hypothesis that AMLR reflects a mechanism by which T cells regulate lymphocyte function.     

Studies on immunoregulatory mechanisms in acute and chronic hepatitis B

Patients with acute hepatitis B and HBV-induced chronic hepatitis as well as normal control persons participated in the study. Hepatitis patients of both groups have decreased OKT4+/OKT8+T cell ratios due to an percental increase of OKT8+T cells in peripheral blood compared to the data of controls. Lymphocyte cultures of chronic hepatitis patients show reduced DNA synthesis after stimulation by allogeneic non-T cells, PHA, Con A and PWM. PWM-induced immunoglobulin secretion by B cells, determined by means of a reverse haemolytic plaque assay (RHPA) and a solid phase ELISA, showed comparable results in hepatitis B patients and controls. The AMLR, which is thought to reflect an autologous immunoregulatory phenomenon, is slightly impaired in cultures of hepatitis B patients in comparison to controls. Con A-induced suppressor cell activity on T cell reactions is decreased in hepatitis, whereas suppressor cell activity on B cell activation is within the same range as in cultures of controls. It is concluded from these data, that suppressor cell activity on T cell function is impaired in hepatitis B, whereas B cell functions and suppressor cell activity on B cell function are in the normal range. The results with the functional assays and the finding of increased proportions of OKT8+T cells in hepatitis B are considered to reflect properties of different T cell subpopulations, responsible for different immunoregulatory functions.     

CD8+/DR+ T gamma cells inhibit the autologous mixed lymphocyte reaction.

The proliferative response of T cells during autologous mixed lymphocyte reactions (AMLR) was affected by depletion of IgG Fc receptor+ T lymphocytes (Tg). Removal of Tg cells resulted in enhanced proliferation, and EA-rosette isolated Tg cells, when added to AMLR cultures as irradiated third components, reduced the uptake of 3H-thymidine by 63-87% in a dose-dependent manner. Negative selection using an avidin-biotin affinity chromatography technique demonstrated that the suppression was mediated by DR+ Tg cells; the major proportion of which also expressed the CD8 antigen. By comparing AMLR supernatants collected from control (lacking Tg) and suppressed (containing Tg) cultures on days 2, 3, and 4, it was established that supernatants from suppressed cultures had significantly reduced levels of cytokine activity. These data indicate that the CD8+/DR+ Tg cells function as suppressor cells during an AMLR and reduce the proliferative response by inhibiting AMLR responder T cells from producing the cytokines necessary for in vitro growth.     

Monoclonal antibodies against HLA-DR antigens acting on stimulator cells prevent OKT8+ T lymphocytes from acquiring sensitivity to interleukin 2 and expressing suppressor function

Purified OKT8⁺ but not OKT4⁺ T lymphocytes generated suppressor activity in autologous mixed lymphocyte reactions (AMLR) in the presence but not in the absence of interleukin 2 (IL 2) as determined in proliferative responses of peripheral blood mononuclear cells induced by Concanavalin A, the OKT3 monoclonal antibody and allogeneic cells (indicator systems for suppressor activity used in this study). Furthermore, treatment of AMLR-activated T cells with the OKT8 antibody plus complement abolished suppressor cell activity whereas treatment of the cells with the OKT4 antibody plus complement did not. The three monoclonal anti-HLA-DR antibodies used in this study abrogated the induction, but not the effector phase, of suppressor cells in AMLR. The anti-DR antibodies acted specifically on the stimulator non-T cells and not on the responder T cells. The addition of IL2 to AMLR cultures performed in the presence of the anti-DR antibodies did not restore or increase the suppressor activity whereas IL2 added to AMLR cultures exposed to control antibodies or medium alone increased the suppressor activity. Moreover, purified OKT8⁺ T cells cocultured with autologous non-T cells and IL2, in the presence of the anti-DR antibodies, neither responded to IL2 by proliferating nor expressed suppressor function. In contrast, OKT8⁺ T cells from similar cultures, but performed in the absence of the anti-DR antibodies or exposed to control antibodies, proliferated to IL2 stimulation and exhibited suppressor activity. Unactivated OKT8⁺ T cells were unresponsive to IL2 and unable to express suppressor function. Finally, the addition of the OKT8 antibody (in the absence of complement) to AMLR cultures had no effect on the generation of suppressor cells. From these results, we conclude the following: (a) OKT8⁺ T lymphocytes become sensitive to IL2 by interacting with HLA-DR antigens on the stimulator non-T cells and, with the help of IL2, they express suppressor cell activity; (b) the OKT8 antigenic determinant on AMLR-activated suppressor cells does not seem to participate in their process of activation; (c) results of previous studies showing that OKT4⁺ T lymphocytes become sensitive to IL1 and are capable of synthesizing IL2 after interaction with HLA-DR on the stimulator cells, and the findings presented here, lead us to suggest that both OKT4⁺ and OKT8⁺ T lymphocytes possess receptors for self HLA-DR antigens and that neither the OKT8 nor the OKT4 antigenic determinants on these cells are involved in the recognition of HLA-DR antigens. The suppressor activity generated in AMLR may be one mechanism whereby effector self-tolerance is maintained in the face of inductive self-recognition.     

Abnormalities in autologous mixed lymphocyte reaction-activated immunologic processes in systemic lupus erythematosus and their possible correction by interleukin 2

The autologous mixed lymphocyte reaction (AMLR) represents the activation, proliferation and differentiation of T cells in response to signals from autologous non-T cells. Upon stimulation by autologous non-T cells, OKT4+ cells produce interleukin 2 (IL2); cells contained within both OKT4+ and OKT8+ cell populations can also be activated by autologous non-T cells to become sensitive to IL2. Once these activated OKT4+ and OKT8+ cells are exposed to IL2 produced by OKT4+ cells, they will proliferate and go on to differentiate into effector cells. Patients with systemic lupus erythematosus (SLE) have a defect in the AMLR. The ability of OKT4+ cells to produce IL2 in the AMLR is impaired. Upon triggering with autologous non-T cells, their OKT8+ cells become sensitive to proliferative signals of IL2; however, their OKT4+ cells fail to express IL2 receptors. These defects are a consistent feature in patients with SLE. AMLR-induced immunologic processes which require cell interactions between OKT4+ cell subpopulations are not correctable even by the addition of normal IL2. However, the immunologic processes mediated through OKT4+-OKT8+ cell interactions can be corrected with normal IL2. The latter finding suggests that the partial correction of the AMLR-induced immunologic processes with IL2 might lead to suppressed B cell hyperactivity of patients with SLE.     

Peripheral T-cell lymphomas. Immunophenotype, lymphokine production, and immunologic functional characteristics of the lymph-node malignant T cells.

Immunophenotype and functions of the malignant T cells to secrete various T-cell derived lymphokines and to respond in autologous mixed lymphocyte reaction (AMLR) and allogeneic mixed lymphocyte reaction (MLR) of the six patients with peripheral T-cell lymphomas (PTL) are presented. Three cases showed CD3/TcR alpha beta discordance (1 CD3+/TcR alpha beta-; 2 CD3-/TcR alpha beta+) and one showed absence of both these antigens (CD3-/TcR alpha beta-). In addition, we found that 50% of cases expressed CD25+, CD38+, and CD71+ activation antigens. The CD3/TcR alpha beta discordance and expressions of activation antigen noted in these cases were typical and similar to those reported from elsewhere. These malignant T cells from all cases whether CD25+ or CD25- (resting) expressed elevated interleukin-2 receptors (IL-2R) on stimulation with phytohemagglutinin (PHA) or human recombinant interleukin-2(rIL-2), and secreted elevated IL-2 by PHA, than do T cells from patients with tuberculosis (TB) or normal healthy controls. These malignant T cells also demonstrated elevated AMLR but deficient MLR B cells growth factor (BCGF) (except in one unusual case) secretion was increased, whereas B-cell differentiation factor (BCDF) secretion decreased. These results suggest that malignant T cells from lymph nodes of patients with PTL have uniform multiple immunologic defects in IL-2, BCGF, and BCDF lymphokine secretion and respond in AMLR and MLR, which do not correlate with immunophenotype or histologic types. These functions differentiate them from lymph-node T cells of patients with TB or blood T cells of normal healthy controls.