Serum HIV antigen and anti-P24-antibodies in 200 HIV seropositive patients: correlation with CD4 and CD8 lymphocyte subsets.

Serum HIV (P24) antigen (Ag) measured by an antigen capture ELISA (Abbott) and anti-P24-antibodies (Abs) measured by a competitive ELISA (Abbott) and by Western Blot (Dupont de Nemours) analysis were correlated with lymphocyte subsets (CD4 and CD8) in 174 HIV seropositive patients without AIDS (non-AIDS) and 26 with AIDS. In the non-AIDS group, 27% of the patients were anti-P24-Ab negative and 21% were Ag positive while in the AIDS group these figures were 62% and 54% respectively (P less than 0.001). Overall, a significant correlation exists between the Ab-Ag profile and the CD4 cell count: the percentage of patients with anti-P24-Ab positive and Ag negative decreases from 90% for patients with more than 900 CD4 cells/microliter to 21% for patients with 100 and less CD4 cells/microliter; on the contrary, the percentage of patients with anti-P24-Ab negative and Ag positive increases from 0% over 800 CD4 cells to 53% under 100 CD4 cells/microliter. A weak correlation may also exist with the CD8 cell count. The subgroup of patients with 1,000 or more CD8 cells/microliter have a higher (but not significant) percentage of subjects with Ag positive and anti-P24-Ab negative than the subgroup with less than 1,000 CD8 cells/microliter. A short-term longitudinal study (mean follow-up: 1 year) was performed on 80 non-AIDS subjects: 77% (10/13) of those who had a CD4 cell decrease (greater than 30%) were initially Ag positive, while only 21% (14/67) of those without a decrease were Ag positive at the beginning (P less than 0.1). Although the relative weight and individual predictive value of each of these parameters need to be classified, they are probably the best biological markers currently available for monitoring clinical trials with experimental drugs.