Differentiation of cerebellar bipotential glial precursors into oligodendrocytes in primary culture: developmental profile of surface antigens and mitotic activity.

We have analyzed the changes in surface antigenic properties of cerebellar bipotential precursors of oligodendrocytes and type-2 astrocytes during their differentiation into oligodendrocytes in serum-free cultures and the relationship between antigen expression and proliferation of these cells. Double immunofluorescence experiments with different monoclonal antibodies (mabs) performed at various stages in vitro and immunocytolysis experiments provided evidence for the following antigenic developmental profile: at early stages in culture the progenitor cells are recognized by the mabs A2B5 and LB1 (which bind to surface gangliosides) but not by other mabs known to label immature or mature oligodendrocytes (04, 01, and anti-galactocerebroside [GalC]). A few days later, the precursors start to express the 04 antigen; at this stage they maintain a bipotential nature and, in the presence of serum, they differentiate into type-2 astrocytes. If maintained in serum-free medium, the progenitor cells enter the oligodendrocyte differentiation compartment, acquiring GalC positivity. Soon after becoming GalC+, the cells lose both bipotentiality and the surface antigens binding A2B5 and LB1. They conserve, however, the antigen binding 04. Experiments of [3H]thymidine autoradiography combined with immunofluorescence showed that a greater proportion of the LB1+ cells incorporated the radioactive nucleoside into their nuclei as compared to the 04+ cells. No incorporation was present in GalC+ oligodendrocytes.