Monoclonal antibody to intermediate filament proteins in astrocytes

A monoclonal antibody was developed using rat astrocytes purified in vitro as the starting antigenic material. Selection of the monoclonal was on the basis of astrocyte binding specificity in brain sections using indirect immunofluorescence techniques. The antibody (RBA2) that was chosen was specific for astrocytes in that it did not stain neurons or oligodendrocytes in frozen brain sections. It did, however, show binding to vascular smooth muscle and meningeal cells. The antigenic determinant(s) was determined to be on filaments of the intermediate-size class in cultured astrocytes and fibroblasts. From analysis of binding patterns in various tissues and in immunoblots, it was found that RBA2 cross-reacted strongly with glial fibrillary acidic protein (GFAP) and desmin. There was a weaker cross-reactivity to a vimentin-associated component. It is proposed that this antibody can be used as an astrocyte and blood vessel marker in brain sections, a vimentin marker in cultures and as a probe of intermediate filament composition and distribution.