EXPRESSION OF CD25 DEFINES PERIPHERAL-BLOOD MONONUCLEAR-CELLS WITH PRODUCTIVE VERSUS LATENT HIV-INFECTION

The present studies were designed to further determine whether the CD2 5 marker could distinguish between cells productively and latently inf ected with HIV. This was accomplished by combining immunotoxin (IT)-me diated killing of CD25(+) cells, highly sensitive indirect immunofluor escence to detect remaining CD25(+) cells, and PCR-mediated amplificat ion of proviral DNA in immunotoxin-treated vs untreated HIV-infected c ells. Our results demonstrate that: 1) By direct immunofluorescence 3 to 8% of PBMCs are CD25(+), whereas by indirect immunofluorescence 30% are CD25(+). The increased number of CD25(+) cells is due to their de tection by the highly sensitive indirect immunofluorescence assay. Up to 60% of the CD25(+) cells are CD4(+) and 12% are CD8(+). 2) Treatmen t of HIV-infected PBMCs with an anti-CD25 IT for 6 days eliminated bot h CD25(high) and CD25(low) cells and decreased the production of p24 b y 99%. 3) Differences in the HIV proviral genome were detected in the unfractionated PBMCs vs PBMCs from which CD25(+) cells had been elimin ated by IT treatment. Hence, PBMCs containing both CD25(+) and CD25(-) cells express all intermediate proviral species and full-length doubl e-stranded proviral DNA. In contrast, CD25(-) quiescent cells contain predominantly intermediate species. These results confirm and extend o ur previous observations that expression of CD25 can distinguish laten tly infected cells from cells producing virus.