Regulatory function of T lymphocytes in the immune response to polyvinyl pyrrolidone. II. Characterization of the intrinsic suppressor and the induced suppressor.

Anti-PVP antibody² response is regulated by two categories of suppressor cells, the intrinsic suppressor and the induced suppressor. The intrinsic suppressor activity was dependent on the thymus-derived cells, which were relatively short-lived, insensitive to the treatment with a small dose of ATS (T₁), resistant to HC, and may be adherent to NW. On the other hand, precursor of the induced suppressor was long-lived, susceptible to ATS (T₂), and insensitive to HC. Induced suppressor itself was sensitive to HC, radiosensitive, and nonadherent to NW.These results suggest that the intrinsic suppressor and the antigen-induced suppressor belong to different subsets of T cells.     

Regulatory function of T lymphocytes in the immune response to polyvinyl pyrrolidone. I. Two categories of suppressor T cells.

The regulation of antibody response of mice to polyvinyl pyrrolidone (PVP) was investigated using three preparations of PVP (K90, K30, and K15) differing from each other in molecular weight. The immunogenicity of PVP was higher as the molecular weight increased. The depletion of thymus-derived cells resulted in the augmentation of anti-PVP response. On the other hand, the response of intact mice to the most immunogenic PVP (K90) was suppressed more or less by the injection of any preparation of PVP 4 days prior to K90. This was most pronounced when the smallest PVP (K15) was preinjected. The suppression, however, was not observed in thymectomized-irradiated-bone marrow reconstituted mice.These results indicated that anti-PVP response was regulated by two different categories of thymus-derived cells, that is, “intrinsic” and “induced” suppressor cells. The activity of the latter was transferrable, PVP-specific, and eliminated by anti-Thy 1 serum and complement. In addition, the mean affinity of anti-PVP plaque-forming antibodies was found to be reduced by the action of “induced” suppressor cells.     

Role of macrophages as modulators but not as stimulators in primary mixed leukocyte reaction

The role of macrophages (M phi) and that of splenic dendritic cells (DC) in the allogeneic mixed leukocyte reaction (MLR) in the mouse have been investigated. In contrast with the high stimulatory capacity of DC, we obtained no evidence in favor of the competence of M phi, whether Ia + or Ia-, as an autonomous stimulator of MLR. However, M phi were found to modulate the level of MLR. Thus, M phi amplified the low level MLR to low dose DC and apparently suppressed the high level MLR to high dose DC. Ia + M phi seemed superior to Ia- M phi in the MLR-enhancing effect. M phi syngeneic to the responder and those to the stimulator suggest that M phi are modulators of immune responses triggered through the mediation of DC.