Abstract
Four antigens designated O1, O2, O3, and O4 have been detected by mouse monoclonal antibodies. They are expressed on the cell surfaces of oligodendrocytes in the central nervous system (see the preceding article, I. Sommer and M. Schachner (1981,
Develop. Biol.
83, 311–327)). O antigens are detectable on freshly trypsinized viable single cell suspensions from early postnatal cerebellum by indirect immunofluorescence procedures. Whereas antigens O1 and O2 are not detectable at birth, O3 and O4 antigens are recognized at this age; at postnatal Day 7 all O antigens are detectable. In monolayer cultures of fetal pons and cerebellum expression of antigens O3 and O4 precedes the detectability of galactocerebroside and antigens O1 and O2. In cultures of 7-day-old mouse cerebellum O1 and almost all O2 antigen-positive cells are also galactocerebroside-positive, whereas O3 and O4 antigens are additionally present on more simple or immature-looking galactocerebroside-negative cells. These O3 and O4 antigen-positive, but galactocerebroside-negative cells are neither positive for GFA protein, tetanus toxin receptors, nor fibronectin. After 7 days in culture more O3 and O4 antigen-positive cells are galactocerebroside-positive than after 2 days. In the peripheral nervous system, in 2 to 7-day-old cultures of neonatal dorsal root ganglion cells, O1 and O2 antigens are hardly detectable under the culture conditions used, whereas antigens O3 and O4 are found on some but not all Schwann cells. After 7 days
in vitro fewer Schwann cells are positive for O3 and O4 antigens than at 2 days. Antigen O4 is found additionally on the surface of dorsal root ganglion neurons, particularly after prolonged culture periods.