Production of HIV in culture fluids of PBMC from LTS and individuals who progressed to AIDS (Progressors). Two isolation methods [A-culture (A) and B-culture (B)] were used to detect HIV production from PBMC of LTS and Progressors. In the A-culture, the PBMC from each individual were stimulated with PHA for 3 days. Seven days later, PHA-activated PBMC from HIV-seronegative donors were added to these cultures. In the B-culture, PHA-activated PBMC from HIV-seronegative donors were added to unstimulated PBMC from LTS and Progressors. Culture fluids were monitored every 3 or 4 days for RT activity.20 Culture fluids were considered to contain HIV if the level of RT activity was ≥10⁴ cpm/mL. The amount of HIV in the culture fluids of A- and B-cultures of LTS and Progressors was found to be statistically different (P < .01 and P = .02, respectively) using the Mann-Whitney U test.