Surface markers of resting and activated human T cells. Functional implications and experimental limits

Shifts in macrophage (M phi) surface phenotypes during tumor growth: association of Mac-2+ and Mac-3+ M phi with immunosuppressive activity

Rat anti-mouse monoclonal antibodies (mAb), anti-Mac-1, -2, and -3, directed against macrophage (M phi) glycoprotein surface antigens, were used to demonstrate a tumor-induced shift in peritoneal M phi subpopulations. This study of the tumor-induced shift was approached in two steps. First, to show that separate phenotypic M phi subpopulations existed and second, to show that a shift in these populations was involved in immunosuppression of the host during tumor growth. Endogenous peroxidase activity was examined among normal and tumor-bearing host (TBH) M phi. A significant increase in the number of peroxidase-positive M phi occurred during tumor growth. Indirect immunofluorescence showed a decrease in Mac-2+ cells and an increase in Mac-3+ cells in TBH M phi populations. When the mAb, anti-Mac-1,-2, and -3 were used in the presence of complement (C), they were cytotoxic for M phi and showed differential depletion of normal and TBH M phi. Peroxidase-positive TBH M phi were susceptible to C-mediated lysis by anti-Mac-1 and -3 but not by anti-Mac-2, whereas no direct relationship was observed among normal host M phi. To demonstrate differences between normal and TBH M phi subpopulations, soluble inhibitory factors were examined from mAb plus C-modified M phi populations. Anti-Mac plus C-treated normal and TBH M phi produced supernatants with different regulatory capabilities as assessed in the mixed-lymphocyte reaction (MLR). Anti-Mac-2 plus C treatment significantly reduced the ability of TBH M phi to produce a soluble suppressor(s) but did not alter normal host M phi-derived suppressor production. In contrast, anti-Mac-1 and -3 plus C treatment of normal host M phi significantly reduced suppressor production. In the TBH, however, anti-Mac-1 plus C had no effect, while anti-Mac-3 plus C had only a limited reduction as compared to the normal host. Determination of levels of prostaglandin E2 (PGE2) in M phi supernatants showed that normal host Mac-1+ M phi were involved in down regulation of PGE2 production. This control was missing in the TBH M phi. Mac-2+ M phi were the apparent producers of PGE2 which accounts for the factor-mediated MLR suppression attributed to TBH Mac-2+ M phi. Collectively, these data suggest that tumor-induced aberrations in immunoregulation can in part be attributed to differences in anti-Mac mAb-defined M phi subpopulations.

Lymphocyte emperipolesis into autologous monocytes in leukocyte cultures exposed to mitogenic lectins

Lymphocyte-monocyte synergistic interaction in cooperative response to mitogens and antigens is well established. This paper describes a less known--antagonistic (effector-target)--lymphocyte-monocyte interaction that came into existence in a leukocyte culture after the commencement of cellular response to concanavalin A, phytohemagglutinin and Wistaria floribunda mitogen. An invasion of lymphocytes into monocytes and monocyte polykaryons has been found 24-48 h after exposure to mitogens. The invasion is not followed by lysosome fusion with lymphocyte-bearing vacuoles, but is associated with a sequential destruction of the vacuole wall, and eventual disintegration of some affected cells. The expression of pan-T-cell surface antigens, staining patterns for nonspecific esterase and acid phosphatase as well as ultrastructural features show that the lymphocytes entering into and those located within monocytes and polykaryons represent activated T-cells. The presence of developed Golgi complexes associated with coated and smooth vesicles, and lysosomal bodies with microvesicles, tubular arrays or dense cores suggest that these T-cells belong to subpopulations which possess cytolytic activities. The lymphocyte invasion is considered cytolytic emperipolesis directed towards some autologous cells of the mononuclear phagocyte series. Its extent depends upon the mitogen concentration, and density of cell population in the culture. It also shows individual variability. The relationship of cytolytic emperipolesis to phagocytosis, and its possible significance as a mechanism of cell-mediated elimination of undesirable cells is discussed.

Analysis of intragraft effector mechanisms associated with human renal allograft rejection: immunohistological studies with monoclonal antibodies

Immunohistological studies of rejecting human renal allografts show that the onset of graft rejection is accompanied by the influx of small numbers of T-cells and macrophages. Both cell types occur in focal aggregates adjacent to the Class II antigen-rich renal vasculature and glomerular Bowman's capsule. Although most of the T-cells express the OKT8+ phenotype of cytotoxic T-cells, analysis with markers for activation of T-cells suggests that the vast majority of these cells are present as functionally inactive precursor cells. Smaller numbers of OKT4+ helper T-cells, NK cells and occasional B-cells are also present. Within a few days, up to 15% of T-cells express receptors for IL-2 and other activation markers, suggesting that they are now functionally active. OKT8+ T-cells continue to predominate, but at least some OKT4+ T-cells appear active as DTH cells. A large influx of mononuclear cells, particularly macrophages, follows and these cells are found within and adjacent to the large Class I antigen-rich intertubular capillary network. Many of these intragraft macrophage express pro-coagulant function, presumably through lymphokine-induced activation, and are enmeshed in a fibrin network. Irreversible kidney damage may result from the combined onslaught of these cellular and humoral mechanisms, and examination of nephrectomy specimens suggests that this destruction is principally mediated by macrophages and polymorphs. These studies, by showing the presence of multiple functionally active cell types within rejecting grafts, provide evidence for a multiplicity of intragraft effector mechanisms. This evidence indicates that in addition to cytotoxic T-cells, DTH cells, macrophages, NK, K and B cells contribute to the rejection process. Further unravelling of the complex response and, hence, greater insights into the basis for more effective immunosuppression are likely to follow from the immunohistological application of monoclonal antibodies to rejecting grafts. However, comparison with animal models of kidney rejection already suggests that there may be important differences in both the initiation and effector phases of human kidney allograft rejection.

Decrease of the OKT8 positive T cell subset in polymyalgia rheumatica. Lack of correlation with disease activity

Peripheral T cell populations were investigated in 35 patients suffering from polymyalgia rheumatica. The total number of T cells was low compared with those of a control group of similar age (P less than 10(-3). This decrease was demonstrated by using both classic E-rosette and monoclonal antibody techniques (OKT3, and OKT4 + OKT8) and was shown to be secondary to a selective T8 defect (P less than 10(-9). There was no correlation between the decrease in T8 (a cytotoxic suppressor T cell subset) and steroid therapy, disease activity, and temporal arteritis, nor between this decrease and the T gamma percentage and the presence of circulating immune complexes (CIC). The T gamma cell percentage was low in the patient group (P less than 10(-5) and correlated with the presence of detectable CIC (P less than 0.05). In contrast to the T8 and T gamma defects, concanavalin A-stimulated cells from 5 selected patients were found capable of suppressing in vitro anti-trinitrophenyl response. This suppression was found in both autologous and allogeneic experiments. From these data one can assume that an immune anomaly (T8 defect) could be the origin of CIC and the disease occurrence.