Activation and proliferation of CD8+ T cells in lymphoid tissues of HIV-1-infected individuals in the absence of the high-affinity IL-2 receptor

Activation of CD8(+) T cells may have important pathogenic implications in HIV-1 infection. Studies of this process have so far been confined to cells from the peripheral blood. In the present study, we have examined molecules involved in activation and proliferation of CD8(+) T cells in lymphoid tissues from HIV-l-infected patients. Tonsillar tissue and blood samples from 13 HIV-1-infected patients and 6 seronegative controls were examined for cell surface expression and the presence of mRNA for CD69, CD25, and HLA-DR. Intonsillar tissue, the number of CD8+ T cells was increased several fold in HIV-l-infected patients compared with controls. The majority of these cells expressed CD69 and HLA-DR, but virtually no tonsillar CD8+ T cells were found to express CD25 on the cell surface or at the mRNA level. Following in vitro activation, however, almost all activated CD8(+) T cells were found to express CD25. Tonsillar CD4(+) T cell numbers were maintained or reduced compared with controls, and a considerable proportion expressed CD25. The data suggest that CD8(+), but not CD4(+) T cells proliferate extensively in lymphoid tissues in HIV-1-infected patients in the absence of the high-affinity interleukin-2 (IL-2) receptor.