FREQUENCY OF CELLS POSITIVE FOR HIV-1 P24 ANTIGEN ASSESSED BY FLOW-CYTOMETRY

Objective: Markers of HIV disease progression such as soluble p24 anti gen detection and CD4 lymphocyte depletion are most useful in the late r stages of HIV disease and are relatively insensitive as therapeutic monitors. Flow cytometric detection of HIV-1 replication in CD4 lympho cytes was evaluated for use as a marker in predicting disease progress ion earlier in the course of HIV disease. Design: To determine whether the number of HIV-1-infected CD4 cells, as measured by p24 antigen de tection, can be correlated with disease progression, we used flow cyto metry to detect intracellular HIV-1 p24 in CD4 lymphocytes from HIV-1- seropositive subjects at ail stages of HIV disease. Methods: Mononucle ar cells from HIV-1-seropositive subjects and uninfected control subje cts were permeabilized and stained with anti-HIV-1 p24 monoclonal anti bodies. The cells were then stained with a fluorescein isothiocyanate- conjugated goat antimurine immunoglobulin G followed by a phycoerythri n-conjugated monoclonal anti-CD4 antibody. The percentage of p24-posit ive CD4 lymphocytes was compared with absolute CD4 counts, soluble p24 detection and Waiter Reed classification. Results: CD4 lymphocyte abs olute counts and the percentage of CD4 lymphocytes declined as the Wai ter Reed classification indicated disease progression. The mean percen tage of p24 antigen-positive CD4 lymphocytes increased with disease pr ogression. Only 30% of Waiter Reed stage 6 subjects were soluble p24 a ntigen-positive, whereas 68% were cellular p24 antigen-positive. Concl usion: The percentage of p24 antigen-positive CD4 lymphocytes increase d as HIV disease progressed. Flow cytometric quantitation of p24 antig en-positive CD4 cells is a useful method of monitoring in vivo HIV rep lication and disease progression.