Autologous Mixed Lymphocyte Culture: Immunoregulatory Aspects

Abstract

It is well established that the autologous mixed lymphocyte reaction (AMLR) represents an immunologic response of T cells to surface antigens on autologous nonT cells. Autologous mixed lymphocyte culture (AMLC) has been shown to possess two main attributes of immune responses : immunologic specificity and memory. AMLC stimulation may result in a variety of effector and immunoregulatory activities. We were interested predominantly in the latter aspects, namely, generation of suppressor cells in AMLC. The critical role in stimulating AMLC response belongs to class II MHC antigens, and any cells expressing class II antigens (B cells, monocytes, and activated T cells) are able to stimulate AMLC reactivity. Cells responding to AMLC stimulation are T lymphocytes, and recent investigations have demonstrated that the cells predominantly proliferating in AMLC are T4 lymphocytes (Engleman et al. 1981). Isolated T8 cells are unable to proliferate in AMLC, presumably, because of lack of interleukin 2 (II.-2) production by these cells. Ability of T8 cells to proliferate in AMLC is restored if T4 cells (as the source of II-2) or exogenous IL-2 are added to the culture (Romain et al. 1984). Nevertheless, even under these circumstances, the relative contribution of T4 cells to the proliferative response in AMLC is much greater than that of T8 cells (Kotani et al. 1984). In this communication, we describe the activity of suppressor cells generated in AMLC and attempt to analyze cellular interactions involved in that phenomenon, at the level of functionally heterogeneous subpopulations within major T cell subsets.