title: Development of a C1q-ABO-ELISA to measure C1q binding by human anti-A alloantibodies.
abstract: Little is known about the correlation between the amount of anti-A antibodies and the respective complement activating capacity. We have therefore developed a new ELISA procedure for the study of complement activation by anti-A antibodies bound to immobilized blood group substance A through the classical pathway. C1q binding capacity of anti-A was then compared to both anti-A immunoglobulin (Ig) isotype serum concentrations and to the hemolysing capacity of O type sera. We have demonstrated that sera with low anti-A IgG and IgM levels produced low C1q binding activity and no hemolysis of human A1 red blood cells (RBC), whereas higher anti-A Ig levels resulted in either weak or strong C1q binding capacity as well as weak or strong RBC hemolysis. A correlation of rs = 0.755 was observed between C1q-ABO-ELISA and hemolysin assay results, although only 58% of the O type sera containing C1q binding anti-A lysed A1 type RBC under the used conditions. The C1q-ABO-ELISA is therefore a more sensitive assay for detecting 'dangerous' O type donors for blood transfusion to A type recipients than screening tests for hemolytic anti-A or determination of anti-A Ig levels alone.
authors.affiliation: Regional Red Cross Blood Transfusion Center, University of Berne, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: von Allmen
authors.forename: R
authors.initials: R
authors.lastname: Rieben
authors.forename: U E
authors.initials: UE
authors.lastname: Nydegger
mesh_terms: D000017:ABO Blood-Group System / Q000032:analysis* / Q000276:immunology*; D000328:Adult; D000918:Antibody Specificity; D000941:Antigens; D003167:Complement Activation; D015922:Complement C1q / Q000276:immunology* / Q000378:metabolism*; D003171:Complement Pathway, Classical; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006460:Hemolysin Proteins; D006801:Humans; D007518:Isoantibodies / Q000276:immunology* / Q000378:metabolism*; D012680:Sensitivity and Specificity
chemical_list: D000017:ABO Blood-Group System; D000941:Antigens; D006460:Hemolysin Proteins; D007518:Isoantibodies; D015922:Complement C1q