Erythrocyte membrane proteins reactive with IgG (warm-reacting) anti-red blood cell autoantibodies: II. Antibodies coprecipitating band 3 and glycophorin A.
In our initial immunochemical study of the red blood cell (RBC) membrane proteins targeted in 20 cases of warm-antibody 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 Wrb epitope may depend on a band 3-GPA interaction. Earlier, anti-Wrb 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-Wrb 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 "pure" anti-Wrb specificity. Two other patients' autoantibodies displayed both IP and serologic evidence for anti-Wrb as a major component in combination with one or more additional specificities. However, among 3 other patients whose autoantibodies coprecipitated band 3 and GPA, there was no reduction in IP or IAT reactivity with Wr(b-) RBCs in 2 and only slight reduction in the third. We conclude (1) that human anti-Wrb autoantibodies, like their murine monoclonal counterparts, coprecipitate band 3 and GPA from human RBCs; but (2) that not all antibodies with this IP behavior have anti-Wrb serologic specificity, as defined by this donor's Wr(b-) RBCs. The possibility of an additional (non-Wrb) RBC epitope dependent on a band 3-GPA interaction is raised.
Leddy
J P
JP
Department of Medicine, University of Rochester School of Medicine and Dentistry, NY.
Wilkinson
S L
SL
Kissel
G E
GE
Passador
S T
ST
Falany
J L
JL
Rosenfeld
S I
SI
D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology; D001323:Autoantibodies / Q000276:immunology*; D001789:Blood Group Antigens / Q000276:immunology*; D000939:Epitopes; D004912:Erythrocytes / Q000276:immunology*; D006021:Glycophorins / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D051379:Mice; D011233:Precipitin Tests
D001457:Anion Exchange Protein 1, Erythrocyte; D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D001789:Blood Group Antigens; D000939:Epitopes; D006021:Glycophorins; D007074:Immunoglobulin G