title: Normal distribution of complement C3b receptor (CR1) numbers on erythrocytes in blood donors: low levels are associated with HLA-B27.
abstract: Blood donors were examined for C3b receptor (CR1) levels on erythrocytes by a microtiter plate enzyme-linked immunosorbent assay and for HLA-A, -B, and -C antigens, C3 phenotypes and blood groups. The CR1 levels among 150 donors varied in the range from 24 to 130% (mean +/- 1 SD = 69.9 +/- 22.9) of an erythrocyte standard, and in accordance with a polygenic model of inheritance the distribution of CR1 was well approximated by a normal curve (chi-square goodness-of-fit test nonsignificant, p = 0.66). Low CR1 levels were associated with HLA-B27 (n = 11, p = 0.05), which was confirmed by investigation of further 20 HLA-B27-positive donors (p = 0.05). The CR1 levels were not associated with a certain C3 phenotype. Possibly, the blood group phenotype M-M + S-s+ is associated with high and the S antigen with low CR1 numbers. The relation between low CR1 numbers and HLA-B27 might be important for the understanding of the association between HLA-B27 and certain inflammatory rheumatological diseases.
mesh_terms: D001782:Blood Donors; D001789:Blood Group Antigens; D004910:Erythrocyte Membrane / Q000276:immunology*; D006680:HLA Antigens / Q000032:analysis*; D015796:HLA-B27 Antigen; D006801:Humans; D011951:Receptors, Complement / Q000276:immunology*; D017463:Receptors, Complement 3b
chemical_list: D001789:Blood Group Antigens; D006680:HLA Antigens; D015796:HLA-B27 Antigen; D011951:Receptors, Complement; D017463:Receptors, Complement 3b