IL-2–induced HIV-1 production in CD45RA⁺/CD4⁺ (RA) and CD45RO⁺/CD4⁺ (RO) purified subsets. RT assay of supernatants from IL-2–stimulated, HIV-1–infected RA and RO cultures. Peak RT activity (day 13) showed a 19-fold difference between the 2 cultures. RT activity was converted to a percent based on maximal activity of the RO culture. Cell proliferation of the corresponding uninfected cultures was measured by ³H-thymidine uptake. Stimulation indices for the RA culture on days 7 and 10 were 3.71 and 4.34, respectively. The corresponding results for the RO culture on days 7 and 10 were 3.62 and 5.16, respectively. Inserts, 2-color FCA of IL-2–stimulated, HIV-1–infected (A) RA and (B) RO cultures 18 days postinfection. The number in each quadrant is the population percentage.