This paper describes immunoblotting and immunoprecipitation studies us
ing monoclonal anti-Wr(a) and anti-Wr(b) antibodies to investigate the
nature of the low-incidence blood group antigen, Wr(a) and its high-i
ncidence allelic antigen Wr(b) No membrane components were identified
by the immunoblotting experiments. Immunoprecipitation studies confirm
ed that the Wr(b) antigen involves both glycophorin A and band 3. The
monoclonal anti-Wr(a), BGU1-WR, failed to immunoprecipitate these or a
ny other red cell membrane component. The significance of these findin
gs is discussed.