Erythrocyte CR1 (C3b/C4b receptor) levels and disease activity in patients with SLE.
Fifty-four patients with systemic lupus erythematosus (SLE) were examined for (1) CR1 (C3b/C4b receptor) levels on erythrocytes by an enzyme-linked immunosorbent assay, (2) levels of circulating immune complexes (IC) by a polyethylene glycol precipitation complement consumption method, and (3) concentrations of C3d split products in plasma by intermediate gel rocket immunoelectrophoresis. A preponderance of low CR1 levels was found among patients with SLE (mean 40%, range 13-106) as compared with normal controls (mean 70%, range 24-130) (p less than 0.001). The concentrations of circulating IC were elevated in 38% of 58 samples. The concentrations of C3d were elevated in 72%, and were positively correlated with the levels of IC (tau = 0.28; p less than 0.005) and with disease activity as assessed by a modification of the UCH/Middlesex criteria. Negative correlations were seen between the CR1 numbers and disease activity (p = 0.01), concentrations of circulating IC (tau = -0.14; p less than 0.005), and C3d (tau = -0.21; p less than 0.005). The changes found in CR1 levels on repeated study were, however, relatively small (less than or equal to 27%; median 5), even during periods of changing disease activity.
D000328:Adult; D000936:Antigen-Antibody Complex / Q000032:analysis*; D003176:Complement C3 / Q000032:analysis*; D015933:Complement C3d; D004797:Enzyme-Linked Immunosorbent Assay; D004912:Erythrocytes / Q000276:immunology*; D005260:Female; D006801:Humans; D007122:Immunoelectrophoresis; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis*; D008297:Male; D011951:Receptors, Complement / Q000032:analysis*; D017463:Receptors, Complement 3b
D000936:Antigen-Antibody Complex; D003176:Complement C3; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D015933:Complement C3d