Characterization by monoclonal antibody of a highly conserved antigenic determinant expressed on human platelet membranes and intermediate filament type III

The murine monoclonal antibody (MoAb) CB21, raised after immunization with sonicated extracts of human platelets, has been shown to react with a line-restricted surface molecule and also a cytoplasmic structure displaying no restriction in terms of lineage and species. The surface structure recognized by the CB2I MoAb is exclusively expressed on the surface membrane of human platelets, being undetectabie on other cells or lines so far tested. After permeabilizalion. The majority of the cells and lines tested with the CB21 MoAb displayed strong cytoplasmic reactivity with a constant typical filamentous distribution. Biochemical and morphological analyses showed that the cytoplasmic counterpart recognized by the CB2I MoAb is the intermediate filament type III.