Lymphocyte subpopulations in the neonate: identification of an immature subset of OKT8-positive, OKT3-negative cells

T cell subpopulations of lymphocytes from cord blood (CBL) of 24 newborns and from peripheral blood (a-PBL) of 24 healthy adult volunteers were assessed in T cell-enriched, T cell depleted and unseparated lymphocyte fractions by using OKT3, 4, 6, and 8 monoclonal antibodies. The results show that T cell-enriched CBL include adult numbers of OKT3+, OKT4+, OKT6+ and OKT8+ lymphocytes whereas the T cell-depleted fraction consists of a high percentage of OKT8+, OKT3-, non-E rosette-forming cells bearing a PNA receptor. The presence of the PNA receptor and the lack of the OKT3+ antigen strongly support the hypothesis that the subset of OKT8+ cells in cord blood includes immature T lymphocytes that may represent an intermediate stage between thymocytes and mature peripheral T cells.     

Natural antibacterial activity against Salmonella typhi in human cord blood

Cord blood mononuclear cells from normal human newborns possess natural antibacterial (NA) activity against Salmonella typhi, as assessed by an in vitro test. NA activity was significantly higher than that observed in PBMC from normal adult donors. Using fractionation on nylon wool and Percoll gradient or C-dependent killing with mAb, it was found that cells of the monocyte-macrophage series and CD4+ T lymphocytes were capable of exerting NA activity in newborns, in contrast with results obtained in adults, where the effector cell was a CD4+ T lymphocyte. The capability of expressing NA activity by CD4+ T lymphocytes from cord blood was also confirmed by flow cytometry sorting. Pretreatment of cord blood mononuclear cells with F(ab')2 fragments against human IgG, but not against human IgA, abrogate the NA activity. Furthermore, human IgA anti-S. typhi cannot arm CD4+ lymphocytes in cord blood. Thus it can be suggested that in newborns, the immune system still being immature, NA activity might be the expression of a mechanism of defence against infections, acting as antibody-dependent cellular cytotoxicity expressed by monocytes and CD4+ T lymphocytes armed with preexisting maternal IgG antibodies. This differs from NA activity of adults which is only mediated by CD4+ T lymphocytes armed by IgA.     

Suppression of adult B cell differentiation in pokeweed mitogen-stimulated cultures by Fc(IgG) receptor-negative T cells from cord blood.

Unfractionated T lymphocytes from cord blood suppressed adult B cell differentiation into immunoglobulin-producing cells in pokeweed mitogen-stimulated co-culture system. Cord blood T cells were fractionated into T cells bearing Fc receptors for IgG (Tgamma cells) and T cells lacking Fc receptors for IgG(Tnon-gamma cells) by rosette formation with ox erythrocytes coated by the IgG fraction of rabbit antisera followed by Ficoll-Hypaque gradient sedimentation. T gamma cells from cord blood, even though isolated after the interaction with immune complexes, showed no suppressor activity on adult B cell differentiation, whereas Tnon-gamma cells exerted strong suppression to a similar extent to that by unfractionated cord T cells. The suppressor activity on B cell differentiation by Tnon-gamma cell as well as by unfractioned T cells from cord blood was completely abrogated by irradiation with 2000 rads. These results indicated that, contrary to suppressor function found in adult T cells, the suppressor activity in cord T cells might be exerted by a T cell subset lacking Fc receptors for IgG(Tnon-gamma cells).     

Characterization of recirculating lymphocytes in rheumatoid arthritis patients: selective deficiency of natural killer cells in thoracic duct lymph

Five patients with rheumatoid arthritis (RA), who were treated by lymphocyte depletion by using thoracic duct drainage (TDD), provided an opportunity to characterize the phenotype and function of their recirculating lymphocytes. We found that: a) thoracic duct lymphocytes (TDL) were similar in their proportion of T cells (83% +/- 6 OKT3+), OKT4+ subset (65% +/- 8), and OKT8+ subset (22% +/- 6) to peripheral blood lymphocytes (PBL): b) fewer natural killer-like cells were present in TDL (5% +/- 4 Leu-7+; 2% +/- 2 Leu-11+: 8% +/- 2 OKM -1+) than in PBL (20% +/- 10 Leu-7+: 11% +/- 6 Leu-11+; 18% +/- 5 OKM -1) (p less than 0.01); c) TDL differed from synovial fluid lymphocytes ( SFL ) and synovial membrane lymphocytes ( SML ) in that TDL lacked a high percentage of activated lymphocytes (T cells bearing Ia antigen, OKT10 , and transferrin receptor): d) immature T cells (expressing either OKT6 antigen or reactive with peanut agglutinin) were not found in TDL even late in the course of TDD: and e) in vitro functional studies demonstrated that TDL were similar to PBL in their ability to synthesize immunoglobulin after mitogen stimulation and to generate cytotoxic T lymphocytes capable of lysing autologous EBV-transformed B cells. However, natural killer activity, as measured by lysis of K562 cells was significantly lower in TDL than PBL (p less than 0.05). These results demonstrate that natural killer cells defined by phenotype and function are excluded from thoracic duct lymph and thus have a circulation pattern different from most T cells.     

Human T-cell-mediated cytotoxicity: Role of subsets and neutralization of cytotoxicity by anti-α-lymphotoxin serum

T cells were isolated from peripheral blood lymphocytes (PBL) and sensitized to allogeneic PBL in a one-way mixed lymphocyte culture. The sensitized cells were fractionated on the basis of the presence of Fc receptors for IgG (T_G+) or IgM (T_M+), or the absence of both IgG and IgM receptors (T_G?,M?). The Cytotoxicity of the T cells was found to reside principally in the T_G?,M? subset. The degree of target cell lysis by this subset was related to the effector-to-target cell ratio. The sensitized T cells were also separated into subsets by treatment with monoclonal OKT4 antibody and complement (yielding OKT8⁺ cells) or OKT8 antibody and complement (yielding OKT4⁺ cells). The OKT8⁺ subset was the more cytotoxic of the two subsets, and this Cytotoxicity was again related to the effector-to-target cell ratio. The T-cell subsets obtained by these methods were characterized by immunologie and morphologic means. The Cytotoxicity of the total sensitized T-cell population or the T_G?,M? subset could be neutralized to a considerable extent by anti-human α-lymphotoxin (anti-α-LT) serum, and α-LT thus appears to have an important role in cytolysis in this system.     

Identification of the T cell subset that produces human gamma interferon

Positive and negative selection procedures combined with cytofluorographic analysis and lysis with monoclonal antibodies were utilized to identify the T lymphocyte subset that produces human gamma interferon (gamma-IFN) (formerly referred to as "immune" or "type II" interferon) in response to mitogen stimulation. Lymphocytes were separated on the basis of their Fc receptors for IgG or IgM, their nonreactivity with IgM or IgG antibodies, and their reactivity with the monoclonal antibodies OKT4, OKT8, OKT11a, and OKM1. Isolated T cell subsets were incubated with the gamma-IFN inducer, phytohemagglutinin. Three days after induction, the cell supernatants were harvested and assayed for interferon. The T cell subset that produces gamma-IFN was identified as E rosette positive with the phenotype: T gamma, T non-micro, OKM1+, OKT4-, OKT8- and OKT11a+. gamma-IFN production by cells was resistant to doses of x-irradiation that abrogate mitogen-induced T suppressor function but was highly sensitive to low doses of 4-hydroperoxycyclophosphamide. These data demonstrate that gamma-IFN is produced by the T gamma, OKM1+ lymphocyte subset, but these cells may also require the presence of accessory monocytes for elaboration of gamma-IFN. The anti-proliferative activity of gamma-IFN may be responsible for the previously described suppressor function of this subset, and gamma-IFN production by T gamma cells may distinguish this subset from the suppressor/cytotoxic functions of the OKT8+ subset or the mitogen-induced OKT4+ suppressor.     

Immature T lymphocytes in human cord blood identified by monoclonal antibodies: a model for the study of the differentiation pathway of T cells in humans

The reactivity of human cord blood lymphocytes was assessed against a panel of monoclonal antibodies (MoAb). The mean proportion of OKT3+ cells (pan-T) was significantly lower in cord blood (52 +/- 13.8%; mean +/- SD) compared with that of adult blood (75 +/- 8.9%) and paralleled well with the E-rosette-forming capacity (50 +/- 16.3%). Both the proportions of OKT4+ cells (helper/inducer phenotype) and of OKT8+ cells (suppressor/cytotoxic phenotype) were significantly reduced in cord blood (43 +/- 11.8% vs 50.3 +/- 7.4% and 20 +/- 10.3% vs 25.6 +/- 6.0%, respectively), while the overall OKT4/OKT8 ratio was increased compared with adult blood (2.87 +/- 1.83 vs 2.04 +/- 0.61). Unlike adult blood, in 30 of the 35 samples of cord blood an overlap was observed between the total proportion of OKT4+ and OKT8+ cells (65 +/- 15.2%) and that of OKT3+ cells (52 +/- 14.3%). Although small numbers of cells coexpressing both antigens were occasionally found, double-staining analysis showed that the overlap in cord blood was mostly due to an expanded proportion of OKT3 (Leu-4)-/OKT8 (Leu-2)+ cells. Relevant proportions of OKT6+ (common thymocyte antigen) and OKT10+ (thymocytes, activated T cells, precursor cells) cells were found in cord blood as opposed to adult blood (10.8 +/- 8.6% vs 0.6 +/- 0.6% and 67 +/- 18.0% vs 8 +/- 2.1%, respectively), while terminal deoxynucleotidyl transferase-positive cells were observed only in two samples of cord blood. A small proportion of T cells (E-rosette+) reacted with the MoAb OKIa1 (HLA-DR). Finally, the proportion of cord blood cells recognized by the MoAb Leu-7 (HNK-1 clone) was almost negligible compared with adult blood (2.8 +/- 2.4% vs 15 +/- 7.5%). These data confirm the immaturity and heterogeneity of cord blood lymphocytes and demonstrate the presence at birth of circulating lymphocytes which express a surface phenotype reminiscent of that found in the late stages of intrathymic differentiation and in some human T-cell leukemias. Human cord blood may thus represent a suitable model for the study of the differentiation pathway of normal and pathological T-cells in humans.     

Developmental changes in humoral suppressor activity released from concanavalin A-stimulated human lymphocytes on B cell differentiation

Cell-free culture supernatants (Con A-activated supernatants) were obtained by incubating peripheral blood lymphocytes (PBL) from cord blood, healthy children of various ages, and healthy adults with mitogenic doses of concanavalin A (Con A) for 48 hr. It is well known that human T lymphocytes are activated by Con A to manifest suppressor function in vitro. One mechanism whereby these suppressor cells act has been shown to be by the secretion of a soluble suppressor factor. The present study has investigated the Con A-inducible suppressor cell function in cord blood, children of various ages, and adults by comparing the ability of each Con A-activated supernatant to inhibit the generation of immunoglobulin-producing cells (Ig-PC) in pokeweed mitogen- (PWM) stimulated cultures of adult PBL. Con A-activated supernatants from adults could markedly suppress the generation of Ig-PC by allogeneic as well as autologous PBL in response to PWM. Such suppression appeared to be equally effective on the generation of IG-PC of 3 major classes, IgG, IgM, and IgA. On the contrary, Con A-activated supernatants from cord blood and newborn infants showed only a negligible suppression on PWM-induced adult B cell differentiation. But the suppressor activity found in Con A-activated supernatants gradually increased with advancing age, and reached approximately to the adult level at 4 yr of age or later. The results suggest that human T lymphocytes may be relatively deficient in their Con A-induced suppressor cell function in the early period of life.     

Functional analysis of monkey lymphocyte subsets defined by OKT4 and OKT8 monoclonal antibodies

The percentages of rhesus monkey blood lymphocytes (PBL) reactive with OKT4 and OKT8 antibodies and the $\text{OKT}\text{4}\text{OKT}\text{8}$ ratio showed significant correlations with the log of the immunoglobulin plaque-forming cell (PFC) response after stimulation with pokeweed mitogen (PWM). These correlations suggested that monkey OKT4⁺ cells function as “helper” cells and OKT8⁺ cells function as “suppressor” cells for the PFC response. This was confirmed by separation and study of enriched T- and B-cell subpopulations. OKT8-depleted (OKT4⁺) and OKT4-depleted (OKT8⁺) cells were obtained by treatment of purified T cells with antibody and complement. OKT4⁺ cells augmented the PWM-induced B-cell differentiation into PFC but OKT8⁺ cells did not. OKT8⁺ cells suppressed the PFC response by mixtures of B cells and OKT4⁺ cells. OKT8 antibodies also detected a suppressive cell subset in African green monkeys since the percentage of OKT8⁺ cells showed a negative correlation with the log PFC response. OKT4 antibodies failed to bind to African green monkey PBL.     

TPA, tumor promoter-induced suppression of immunoglobulin secretion in human blood lymphocytes

12-O-Tetradecanoylphorbol-13-acetate (TPA) modulates DNA synthesis and differentiation of normal and malignant human lymphoid cells. Using the reverse plaque forming assay and radioimmunoassay, we showed that nontoxic concentrations of TPA (5 to 10 ng/ml) inhibited Ig secretion of peripheral blood lymphocytes. This inhibition was dependent on T lymphocytes and not monocytes; TPA treatment of the B cell-enriched fraction slightly enhanced Ig secretion. Suppression was evident when the proportion of TPA-pretreated T lymphocytes exceeded 50%. TPA-induced suppressor cells were present in both OKT8+ (suppressor/cytotoxic) and OKT4+ ("helper/inducer") subpopulations. The suppression was diminished but not abolished by the irradiation of T lymphocytes. In addition, TPA treatment modulated the expression of OKT4 antigen, whereas the expression of OKT8, 9.6 (sheep erythrocyte receptors) and surface Ig remained unchanged. Modulation of OKT4 was energy dependent and was not blocked by a maximal saturation of TPA receptors at 4 degrees C. We postulate that TPA-induced suppression of Ig secretion is T cell dependent and is likely to be associated with proliferation and activation of OKT8+ and OKT4+ lymphocytes and the induction of OKT4+ suppressor cells.     

Changes in the ratio of T-lymphocyte subpopulations in various cytological samples of Plummer's thyroid adenoma

In order to correlate possible alterations of cell-mediated immune response with the evolutive phases of Plummer Adenoma (P. A.), T lymphocytes subpopulations in FNA samples and in peripheral blood lymphocytes (PBL) have been studied in 5 patients with autonomous nodules. The lymphocyte component in FNA and peripheral blood has been isolated by Lymphoprep gradient centrifugation; the analysis of T helper and T suppressor subpopulations was made by indirect immunofluorescence with OKT8 and OKT4 monoclonal antibodies. Our results show a reduction in OKT4/OKT8 ratio in cytological samples compared with PBL in patients with P. A., while in control subjects there was not statistically significant difference. In the patients with P. A., the relative increase of OKT8 lymphocytes in FNA compared with PBL is correlated with the functional state, that is toxic adenomas have a lower OKT4/OKT8 ratio compared with nodules in pre-toxic phase. In conclusion: T lymphocyte subpopulations typing in FNA demonstrate that, even in this type of hyperthyroidism, immune response disorders are present and consist of relative increase of suppressor/cytotoxic T cells, compared to T helper cells.     

Predominance of helper-inducer T cells in mesenteric lymph nodes and intestinal lamina propria of normal nonhuman primates

To define the characteristics of T cells associated with the gastrointestinal tract, the phenotypes and immunoregulatory function of T cells from mesenteric lymph node (MLN) and lamina propria lymphocytes (LPL) were compared to peripheral blood (PBL) and spleen lymphocytes in normal nonhuman primates. Mesenteric lymph node lymphocytes were characterized by a higher proportion of Leu-3+(CD4+) and 9.3+(alpha-Tp44) lymphocytes and a lower proportion of Leu-2+(CD8) lymphocytes than lymphocytes in other sites. LPL and MLN lymphocytes were both characterized by a higher proportion of cells having the helper-inducer phenotypes (Leu-3+, Leu-8+, Leu-3+, 2H4+) compared to PBL. A lower proportion of cells with the suppressor-inducer phenotypes (Leu-3+, Leu-8+, Leu-3+, 2H4+) was found in LPL, but not in MLN lymphocytes compared to PBL. In studies of the Leu-2+ T cells, it was found that whereas PBL, spleen, and LPL contained approximately equal proportions of Leu-2+, Leu-15+ (suppressor phenotype) and Leu-2+, 9.3+ lymphocytes (cytolytic T-cell phenotype), the MLN T cells were predominantly Leu-2+, 9.3+. Furthermore, the Leu-3/Leu-2 ratio was significantly higher in MLN compared to other sites. In pokeweed mitogen-stimulated cultures, the highest helper function for Ig synthesis was found in MLN. Cells from none of the sites studied showed evidence of increased suppressor cell activity. These results show that MLN and LPL T cells in normal nonhuman primates differ from T cells in peripheral blood and spleen. While both MLN and LPL have a high proportion of T cells with the helper-inducer phenotype, cells with the suppressor-effector phenotype are infrequent in MLN, while cells with the suppressor-inducer phenotype are infrequent in LPL.     

Suppressor cell function of human granular lymphocytes identified by the HNK-1 (Leu 7) monoclonal antibody

The HNK-1 (Leu 7) differentiation antigen defines a subpopulation of human granular lymphocytes with natural killer (NK) and K cell function. In this study, we investigated whether HNK-1+ cells, identified with the monoclonal antibody and purified with a fluorescence-activated cell sorter (FACS), could function as suppressor cells. The results demonstrated that purified HNK-1+ cells efficiently suppressed both PWM-induced IgG production by B cells and T cell proliferation in mixed lymphocyte reactions (MLR). Manifestation of this suppressor cell activity required immune complex activation and was partially sensitive to 2000 rad irradiation. This suppressor cell activity was predominantly mediated by a subset of HNK-1+ cells that have previously been shown to have maximum NK function and lack expression of the E rosette (ER) receptor and T cell antigens (e.g., T3 and T8). Thus, HNK-1+ER- cells suppressed a MLR by an average 52%; HNK-1+ER+ were one-half as efficient, causing an average 23% suppression. For comparison, we also examined the characteristics of Leu 2a+ suppressor T lymphocytes. In contrast to HNK-1+ cells, unactivated Leu 2a+ cells suppressed both B and T cell responses. This suppressor activity was not augmented by immune complex activation and was absolutely radio-sensitive in PWM assays. HNK-1+ cells, especially the HNK+ER- subset, can therefore mediate suppressor cell function in addition to their spontaneous cytotoxic function. Furthermore, some of their suppressor cell properties are distinct from those attributed to other types of suppressor lymphocytes.     

Mechanism of action of a suppressor-activating factor (SAF) produced by a human T cell line

We previously described a potent suppressor-activating factor (SAF) produced constitutively by a 6-thioguanine-resistant mutant of the human T cell line CEM. In the present study, we investigated the mechanism of action of SAF. After a brief (4- to 18-hr) exposure to SAF at 37 degrees C, T lymphocytes (either unseparated, or purified OKT4+ and OKT8+ subpopulations), but not B lymphocytes, suppressed allogeneic and syngeneic T cells in co-culture experiments, apparently via the release of a suppressor activity. The total T cell-released suppressor activity (TRSA) accumulated after 3 days culture post-treatment was about 100- to 500-fold higher than the original suppressor activity (SAF) added to trigger the release. Arresting protein or DNA synthesis, or even killing the cells did not affect the release of TRSA by T lymphocytes, but lowering the incubation temperature to 4 degrees C reduced it drastically. Pre-treatment of T lymphocytes with the metabolic inhibitor, sodium azide, or the adenylate cyclase stimulator, prostaglandin E2, or the addition of exogenous dibutyryl cAMP, all suppressed the release of TRSA. The presence of monoclonal antibody OKT3, but not OKT4 or OKT8, enhanced the release of TRSA. The presence of OKT11 blocked the release of SAF. The functional characteristics of TRSA appeared to be identical to those of SAF. However, unlike SAF, interaction of T lymphocytes with TRSA triggered only marginal enhancement of suppressor activity. In addition, the kinetics of the suppression mediated by SAF showed a much larger increment as a function of time than that mediated by TRSA. Taken together, the data suggest that SAF might represent an activated form of SAF, and that the continuous activation of SAF by lymphocytes in culture may account for its high potency in suppressing T cell proliferation in vitro.     

Further characterization of mitogen-induced autorosette-forming cells: correlation with T-cell subsets and with lymphocyte proliferative responses to mitogens

Spontaneous autologous rosette-forming cells (ARFC), which form rosettes with autologous erythrocytes, have been of interest as a subset of thymus-derived lymphocytes (T cells). An association of these cells with concanavalin A (Con A)-induced ARFC has been suggested. Furthermore, the Con A-induced ARFC have been shown to be a suppressor T-cell subset in the Con A-generated suppressor system. We have previously reported the induction of ARFC from T cells by several T-cell mitogens such as phytohemagglutinin-P (PHA) and allogeneic non-T cells other than Con A. In the present report, we further characterized the mitogen-induced ARFC and have extended the study to patients with systemic lupus erythematosus (SLE). We have found that ARFC are also inducible from peripheral blood T cells by pokeweed mitogen (PWM). Studies of T-cell surface markers on the ARFC using OKT monoclonal antibodies confirmed the induction of ARFC from both OKT4- and OKT8-reactive T cells by either Con A, PHA, or PWM stimulation. However, OKT4-reactive T cells were the major cellular source of the ARFC induced by all of the mitogens. In studies of SLE patients, proportions of both Con A- and PWM-induced ARFC were found to be significantly low in PBL of SLE patients treated with moderate or large doses of prednisone, with or without concomitant immunosuppressants, but not in SLE patients without such treatment. Proportional analysis of the T cells and their subsets suggested association of these alterations in the mitogen-induced ARFC with the OKT4-reactive T cells, since a significant decrease in the OKT4-reactive T-cell subset was demonstrated in the PBL of these patients. Proportions of PHA-induced ARFC, however, were not significantly different between SLE patients and healthy adults. Moreover, positive correlations of the mitogen-induced ARFC with lymphocyte proliferative responses to each mitogen were established in both SLE patients and healthy adults. These results further support our previous observation that suggest the receptors for autologous erythrocytes are enhanced or reexpressed on those T cells which are highly activated by mitogens.     

Effector activity of OKT4+ and OKT8+ T-cell subsets in lectin-dependent cell-mediated cytotoxicity against adherent HEp-2 cells

The role of OKT4+ and OKT8+ T-cell subsets was studied in lectin-dependent cell-mediated cytotoxicity (LDCC) against adherent HEp-2 human epipharynx carcinoma target cells. LDCC was evaluated by detachment from the monolayer of [3H]thymidine prelabeled HEp-2 cells in a 24-hr assay with a concanavalin A (Con A) dose of 25 microgram/ml at effector:target cell ratios of 5:1, 25:1, and 50:1. Under these conditions but without Con A considerable natural cell-mediated cytotoxicity (NCMC) was not elicited; however, the cytotoxicity was significantly augmented in the presence of Con A (=LDCC) by sheep erythrocyte rosette-forming T lymphocytes and by both OKT4+ and OKT8+ T-cell fractions. LDCC activity by isolated OKT8+ T cells was superior to that by OKT4+ T cells and unfractionated T lymphocytes. By contrast, addition of either OKT4+ or OKT8+ T cells together with unfractionated T lymphocytes, or OKT4+ and OKT8+ T cells mixed at ratios of 1:1, 1:2, and 2:1, to target cells did not result in major differences in comparison of LDCC activities by these mixed effector cell populations with each other or with that by unfractionated T lymphocytes. Parallel studies were carried out to determine the effect of OKT4+ and OKT8+ T-cell subsets on the Con A-induced proliferation of peripheral blood mononuclear cells (PBMC). While OKT8+ T cells inhibited the mitogenic response to Con A, OKT4+ T lymphocytes had no major effect. A higher responsiveness of the OKT8+ to OKT4+ T-cell subset in LDCC to HEp-2 targets and in Con A-induced lymphocyte proliferation is suggested.     

A defect in the suppressor circuits among OKT4+ cell populations in patients with systemic lupus erythematosus occurs independently of a defect in the OKT8+ suppressor T cell function

The autologous mixed lymphocyte reaction (MLR) is thought to be part of a regulatory role of T cells on B cell function. OKT4+, but not OKT8+, cells can proliferate in response to autologous non-T cells. Moreover, the OKT4+ cell population activated early in the course of autologous MLR functioned as inducer cells for the differentiation of B cells, whereas later in the response, the activated OKT4+ cells were particularly enriched in suppressor cells. A part of the autologous MLR appears to be an important pathway for the activation of feedback suppression mechanisms among cells contained within the OKT4+ populations. Patients with systemic lupus erythematosus (SLE) were studied with regard to the following OKT4+ cell functions in vitro after activation in the autologous MLR: a) proliferative response, and b) helper and suppressor activities for differentiation of B cells. A marked reduction in the proliferative response of OKT4+ cells was observed in SLE patients. SLE OKT4+ cells activated in the autologous MLR could function as helper cells but could not exert any suppressor activity. This OKT4+ cell abnormality was present regardless of the disease activity, and occurred in the absence of autoantibodies including anti-T cell antibodies. Instead, SLE anti-T cell antibodies could preferentially eliminate cells bearing the OKT8+ phenotype characteristic of suppressor cells in populations of normal T cells. These results suggest that the defect in the suppressor circuits among OKT4+ cell populations is intrinsic to SLE lymphocytes and that the OKT8+ suppressor T cell defect is caused by antibodies produced by the B cells of SLE patients.     

Regulation of cellular immune response against autologous human melanoma. I. Evidence for cell-mediated suppression of in vitro cytotoxic immune response

The potential existence of down-regulation of cytotoxic immune response against an autologous human melanoma line was investigated as a possible explanation for cytotoxic unresponsiveness against the autologous melanoma cells. The melanoma cell line, PJ-M, was established and lymph node resident lymphocytes (LNL) were isolated from a lymph node which was partially infiltrated with the melanoma cells. Autologous peripheral blood lymphocytes (PBL) were sensitized in in vitro co-culture (IVC) against radiated PJ-M cells in the presence or absence of PJ-M-sensitized LNL and enriched suppressor (OKT8+) or inducer (OKT4+) LNL populations, and were assayed for cytotoxicity in a 4-hr 51Cr-release microcytotoxicity assay. Significant cytotoxic response against PJ-M could be generated in the PBL, but not in the LNL. The addition of sensitized, unfractionated LNL, OKT8+, or OKT4+ LNL populations abrogated cytotoxic response in the PBL against PJ-M. The suppression of cytotoxic response was induced selectively against the PJ-M targets, because IVC of PBL in the presence of the sensitized LNL did not affect the generation of polyclonal cytotoxic alloreactivities, nor did they abrogate the generation of cytotoxic response against allogeneic targets in IVC against the corresponding allogeneic targets. These results suggest the possibility that cytotoxic immune response against the autologous melanoma cells might have been suppressed by the individual's own immunoregulatory circuit.     

Glucocorticoid receptors in subpopulations of human lymphocytes defined by monoclonal antibodies

Glucocorticoid receptors (GR) were investigated in subpopulations of lymphocytes identified by monoclonal antibodies. Purified T (OKT3+) and non-T lymphocyte subpopulations were isolated from human peripheral blood using Degalan bead columns coated with rabbit anti-human IgG. Purified subpopulations of OKT4+ and OKT8+ lymphocytes were obtained by coating the nonadherent population (T cells) from the first column with OKT4+ or OKT8+ and pouring it into a second Degalan column, coated with goat anti-mouse IgG. GR content and affinity were analyzed by a whole cell assay with [3H]dexamethasone as tracer. The numbers of GR in lymphocyte subpopulations (OKT3+ cells, non-T cells, OKT4+, and OKT8+ cells) were nearly equal. It is concluded that the differential effects of glucocorticoids on the circulatory kinetics of OKT4+ and OKT8+ cells probably are not related to differences in glucocorticoid receptors of these T-cell subpopulations.     

Secretions of anti-myelin-associated glycoprotein antibodies by B cells from patients with neuropathy and nonmalignant monoclonal gammopathy

Four patients with peripheral neuropathy and nonmalignant monoclonal gammopathy with anti-myelin-associated glycoprotein (MAG) antibodies were studied to determine whether secretion of anti-MAG IgM antibodies by B cells was autonomous, or whether the monoclonal B cells were responsive to T cells. Secretion of anti-MAG IgM by isolated B cells was stimulated by the addition of increasing numbers of pokeweed mitogen (PWM)-activated autologous OKT4+ helper T cells in all four patients. Secretion of anti-MAG IgM by peripheral blood lymphocytes was dependent on the ratio of OKT4+ T helper cells to OKT8+ T suppressor/cytotoxic cells. In three patients with an OKT4+ to OKT8+ T-cell ratio of 2:1, PWM activation stimulated secretion of anti-MAG IgM; in one patient with an OKT4+ to OKT8+ ratio of 1:2, activation by PWM suppressed anti-MAG IgM secretion. These studies suggest that the monoclonal B cells that secrete anti-MAG IgM are responsive to regulatory T cells.