HIGH PERCENTAGES OF CD4-POSITIVE LYMPHOCYTES HARBOR THE HIV-1 PROVIRUS IN THE BLOOD OF CERTAIN INFECTED INDIVIDUALS

Objectives: HIV-1 infection of humans leads to states of immunosuppression. Therefore, we sought to determine precise levels of HIV-1 infection of cells in vivo, as these data may assist in the understanding of the pathogenetic processes involved in HIV infection. Design and methods: We have developed an in situ polymerase chain reaction (IS-PCR), which allows amplification of various genetic elements within intact cells. Initial studies using this technique have demonstrated higher levels of HIV-1 provirus in unfractionated peripheral blood mononuclear cells (PBMC) of infected individuals than have been demonstrated in many previous studies using standard PCR techniques. This study describes a combined protocol in which an immunomagnetic bead separation technique is used with IS-PCR to specifically determine cellular reservoirs for HIV-1 and levels of infected cell types in the peripheral blood. Results: CD4-positive lymphocytes infected with HIV-1 ranged from 0.2 to 69% in the 42 HIV-1-infected patients evaluated. The percentages of HIV-1-infected CD4-positive lymphocytes increased significantly with advancing stages of disease. These procedures also demonstrated that, with the exception of small percentages of infected peripheral blood monocytes, the CD4-positive lymphocyte is clearly the major cellular reservoir for HIV-1 in the peripheral blood. Conclusions: These data suggest that, in certain infected individuals, high levels of CD4-positive lymphocytes may harbor the HIV-1 provirus. Thus, the levels of infected lymphocytes are consistent with possible direct effects of HIV-1 on lymphocyte depletion in vivo.