Deficiency of erythrocyte C3b receptor (CR1) in AIDS and AIDS-related syndromes.

The expression of C3b receptors (CR1) on erythrocytes of gay men at various levels of risk for AIDS was studied. Fourty-nine heterosexual male controls had a mean (X) +/- standard deviation of 516 +/- 136 CR1 per erythrocyte (CR1-3); 17 asymptomatic gay men had X = 423 +/- 156, 16 gay men with one AIDS-related complex (ARC) symptom or sign had X = 342 +/- 154, 9 patients with ARC had X = 252 +/- 76, and 14 gay men with AIDS had X = 173 +/- 76 CR1-E. The patients with ARC and AIDS had a highly significant decrease in CR1-E when compared with normal individuals (p = less than 0.001) and studies of families of 4 AIDS patients suggest that this defect is acquired.