A monoclonal antibody that recognizes an adhesion molecule expressed by certain cells of neuroectodermal and...

A cell surface glycoprotein has been identified from detergent extracts of cultured astrocytes obtained from neonatal rat cerebral cortex using a mouse monoclonal antibody (MAb 1A1). This antibody inhibits neuron-astrocyte and astrocyte-astrocyte adhesion, as well as neurite outgrowth on astrocytes in vitro. The MAb 1A1 does not bind to tissue sections, but by indirect immunofluorescence of dissociated CNS cultures, the antibody labels subpopulations of astrocytes (flat, type 1 astrocytes and Bergmann glia) and cells derived from the mesenchyme (leptomeninges and fibroblasts). The latter cells are labeled only when grown to confluency. The 1A1 cell surface glycoprotein appears as a single band of approximately 135 kDa on both reduced and nonreduced SDS-PAGE. Based on its unique cell-type distribution, functional properties and biochemical analysis, this 135-kDa protein appears to be distinct from other known adhesion molecules expressed on astrocytes. This molecule, thus, belongs to the growing list of cell adhesion molecules that may play a role in histogenesis and axonal growth during development of the mammalian CNS.