Erythrocyte Membrane Proteins Reactive With IgG (Warm-Reacting) Anti-Red Blood Cell Autoantibodies: 11. Antibodies Coprecipitating

In our initial immunochemical study of the red blood cell (RBCI membrane proteins targeted in 20 cases of warmantibody autoimmune hemolytic anemia (AHA), RBC eluates of 6 patients mediated immunoprecipitation (IP) of both band 3 and glycophorin A (GPA). This dual IP pattern had previously been observed with murine monoclonal antibodies (MoAbs) against the high frequency blood group antigen, Wrb (Wright), suggesting that the W 8 epitope may depend on a band 3-GPA interaction. Earlier, anti-We had been identified serologically as a prominent non-Rh specificity of AHA autoantibodies. In the present study, 6 autoantibody eluates immunoprecipitating band 3 and GPA from common Wr(b+) RBCs were retested, in parallel with murine anti-WP MoAbs, against very rare Wr(a+b-) En(a+) RBCs. One patient's autoantibodies were unreactive with the Wr(b-) RBCs by either IP or indirect antiglobulin test (IAT) and were judged to have