Regulation of the Immune Response by the Major Histocompatibility System

IN the past decade, it has become apparent that the immune response is precisely regulated.^{1 2 3 4 5} This regulation operates at several levels and determines whether there will be an immune response to an antigen, what the magnitude of the response will be, which classes of antibodies will be produced, and which subsets of antigen-specific T cells will be induced. In retrospect, it seems obvious that regulation would be required to prevent the immune response to each antigen from assuming the proportions of a polyclonal gammopathy or a lymphoproliferative syndrome.Most antigens elicit a complex interacting set, or network, of functionally distinct, . . .