[Free dissociated and precipitated p24 antigenemia of HIV-1 in subjects of the black race].

P24/HIV-1 antigen in the sera from 41 HIV-1-infected Black individuals, living in the Central African Republic (n = 17) and in France (n = 24), and in 21 HIV-1-infected Caucasians patients, matched on the stages of the disease, has been detected and quantified by ELISA, without and with acid pretreatment of the sera by HC1 or by glycine, and after ultracentrifugation of serum. Free p24 antigenemia was detected less frequently in Black patients (9.7%), than in Caucasian controls (33%) (p < 0.05). Decomplexed p24 antigenemia was detected in 34% of patients after dissociation of circulating immune complexes (CIC) by HC1 (p < 0.01) and in 44% of patients after dissociation of CIC by glycine (p < 0.001). However, the mean concentration of decomplexed p24 antigenemia of positive sera was higher after pretreatment by HC1 (88 pg/ml) than by glycine (52 pg/ml), suggesting that a strong acid is more convenient than a weak one to disrupt the CIC in Black individuals. After ultracentrifugation of the serum, the detection of p24 antigen was not significantly increased. Acid dissociation of CIC is a usefull method to increase the sensitivity of detection of circulating p24 antigen in HIV-1-infected Black individuals.