Characterization of responding cells in oxidative mitogen stimulation. III. Presence of I-A- and I-J, E, C-subregion gene products on the surface of required cells.

Ia antigens coded by genes of the murine major histocompatibility complex are expressed on the surface of a population of cells critical to the proliferative response of murine spleen cells to the oxidative mitogen neuraminidase/galactose oxidase. By selective depletion with antiserum and complement, Ia antigens coded (or determined) by the I-A and I-J, E, C subregions of the Ir region can be detected on the surface of cells required for the response. In addition, I-A-subregion products have a functional significance in cellular activation which can be demonstrated by blocking experiments with anti-Ia serum in the absence of complement.