Involvement of the HLA system in the immune response.

Abstract

Within recent years it has become clear that the major histocompatibility complex (MHC) plays a fundamental biological role in the cooperation between various cells in the immune responses. Most of this knowledge derives from studies of animals and has been summarized in recent reviews by Benacerraf and Germain (1978), Rosenthal (1978), Snell (1978), Thomas et al. (1978), and Zinkernagel (1978). It appears that MHC is involved primarily, perhaps exclusively, in thymus-dependent immunity, i.e. in cell-mediated immunity and usually in the induction of IgG antibody production. More specifically, various MHC factors play a role in the cooperation between the cell types responsible for thymus-dependent immunity: macrophages, T-helper lymphocytes, T-suppressor lymphocytes, T-effector lymphocytes, and certain B lymphocytes. A simplified scheme of these cooperations is given in Table 1 which also indicates which MHC factors seem to be involved in the various steps. In the early stages of the immunization, macrophages cooperate with T-helper lymphocytes and I region MHC determinants play a role here. These determinants are also involved in the cooperation between T-helper lymphocytes and B lymphocytes. In contrast, it is the H-2D and H-2K antigens which must be recognized on virus-infected or hapten-conjugated target cells when these are lysed by T-effector lymphocytes. Finally, the IJ antigens have been implicated in the action of suppressor cells.