Reactivity of a human monoclonal antibody against Rh D with the intermediate filament protein vimentin.

The human IgM anti-Rh D antibody MAD-2 has previously been shown to react with human and animal tissues and leucocytes. Double labelling immunofluorescence with MAD-2 and a mouse monoclonal antibody against vimentin, the intermediate filament protein of cells of mesenchymal origin, showed coincidental staining which was distinct from that seen with antibodies against other cytoskeletal proteins. Using immunoblotting, both MAD-2 and anti-vimentin reacted with a 55 kDa tissue component, and with purified vimentin. These results show that the major tissue and leucocyte protein recognized by MAD-2 is vimentin.