STRUCTURAL POLYMORPHISMS OF COMPLEMENT RECEPTOR-1 (CR-1) IN SYSTEMIC LUPUS-ERYTHEMATOSUS (SLE) PATIENTS AND NORMAL CONTROLS OF 3 ETHNIC-GROUPS

CR1 exhibits a molecular weight polymorphism and variability in the nu mber of C3b-binding sites. Because this may affect immune complex clea rance, we used erythrocytes to investigate the CR1 size polymorphism i n SLE patients from three ethnic groups. The CR1-C allele was found mo re frequently in African-Americans, but the frequency did not differ b etween controls (10%, n = 63) and SLE patients (9%, n = 79). A 160-kD band similar to CR1-C was noted in a number of patients and was shown to be a proteolytic cleavage fragment. The study shows that the smalle st form of CR1, i.e. CR1-C, is not a genetic risk factor for SLE and t hat the frequencies of the CR1 structural alleles do not differ from r ace-matched healthy controls.