Some immature tetanus toxin-positive cells share antigenic properties with subclasses of glial cells. An immunofluorescence study in the developing nervous system of the mouse using a new monoclonal antibody S1

Monoclonal antibody S1 reacts in monolayer cultures with the cell surfaces of oligodendrocytes and a subclass of astrocytes derived from early postnatal mouse cerebellum, cerebrum and spinal cord, as well as with some glial cells in mouse retina but not in dorsal root ganglia. At earlier developmental stages S1 antigen is present in addition to oligodendrocytes and astrocytes on some tetanus toxin-positive neurons. S1 antigen is a developmentally early marker, detectable already in freshly trypsinized single cell suspensions from cerebella of 13-day-old embryos. Immunocytolysis of S1 antigen-bearing cells leads to reappearance of S1 positive glial cells but not tetanus toxin receptor-positive neurons. S1 antigen is also expressed in rat, rabbit, chicken and human. When cultured cells are permeabilized with denaturing agents, S1 antibody not only labels cell surfaces of some glial cells and, depending on the developmental stage, some neuronal cells but also intracellular components of all astrocytes, oligodendrocytes, neurons and fibroblasts.