The differentiation of O-2A progenitor cells into oligodendrocytes is associated with a loss of inducibility of Ia antigens.

Current data suggest that some astrocytes, one of the 3 main types of macroglia in the central nervous system (CNS), can be induced by interferon-gamma (IFN-gamma) to express major histocompatibility complex class II antigens (immune-associated or Ia) and present antigen to T lymphocytes. In contrast, oligodendrocytes, another type of macroglia, cannot be induced to express Ia. The astrocytes which have been shown to express Ia are from a particular glial lineage and are called type-1 astrocytes. The oligodendrocyte-type-2 astrocyte (O-2A) lineage, which gives rise to oligodendrocytes, also gives rise to a second class of astrocytes called type-2 astrocytes and the ability of type-2 astrocytes or the common O-2A progenitor cell to express Ia is not known. We have now found that both type-2 astrocytes and O-2A progenitor cells can be induced to express Ia by IFN-gamma but Ia expression is not induced in oligodendrocytes in parallel cultures. Thus, it appears that differentiation of O-2A progenitor cells into oligodendrocytes is specifically associated with a loss of inducibility of Ia. This apparent loss of the capacity for Ia expression, and presumably antigen presentation, in oligodendrocytes (the cells which produce myelin in the CNS) is of particular interest in view of the ability of immunization of myelin components to produce autoimmune-mediated paralytic disease.