Expression of major histocompatibility complex antigens in neonate rat primary mixed glial cultures

Primary mixed glial cultures containing astrocytes, oligodendrocytes and macrophages have been cultured from cerebral hemispheres of neonate rats and examined by indirect immunofluorescence for the expression of class I and II RT1 major histocompatibility complex-coded antigens. None of these cells expressed detectable levels of either class I or II antigens except for the macrophages which were weakly class I positive. Treatment with lymphokine-containing supernatant from concanavalin A-activated splenic lymphocytes resulted in increased expression of class I antigens on all cells together with the appearance of class II RT1.B and RT1.D antigens on macrophages and a small proportion of type 1/protoplasmic astrocytes. The identity of the Ia antigens was confirmed by immunoprecipitation from lysates of surface-iodinated cells. The ability of lymphokine-treated mixed glial cultures to stimulate proliferation of allogeneic lymphocytes provides additional evidence of Ia induction. A possible role for these Ia+, putative antigen-presenting cells in delayed type hypersensitivity in the central nervous system is discussed.