CR1 activity on erythrocytes and renal glomeruli in patients with renal disorders.

Complement receptors for C3b/C4b (CRI) on erythrocytes (ERC1) and renal glomeruli (GCR1) were examined in patients with different types of renal disorders. Normal ECR1 activity was found on erythrocytes from patients with IgA glomerulonephritis, benign nephrosclerosis and other types of renal diseases. In patients with systemic lupus erythematosus (SLE) and glomerulonephritis ECR1 activity was low or absent in 75% of the patients. The GCR1 activity, however, was normal except in areas with complement deposits where GCR1 activity was abolished. During treatment with corticosteroids and azathioprine of patients with SLE the clinical response was followed by increased functional ECR1 activity. In those patients who did not respond the ECR1 activity was persistently low. Three patients with renal transplant all showed increased ECR1 activity.