Infection of T Cell Subsets by HIV-1 and the Effects of Interleukin-12

CD4⁺ lymphocytes constitute one of the major cell targets for human immunodeficiency virus type 1 (HIV1) infection. The eventual loss of CD4⁺ lymphocytes contributes substantially to the pathogensis of HIV-1 and development of acquired immunodeficiency syndrome (AIDS). CD4⁺ lymphocytes consist of the subgroups Thl, Th2, and Th0, which differ in their cytokine profile. Thl cells produce cytokines that favor cell-mediated immune responses, whereas Th2 cells produce cytokines that favor humoral immunity. Th0 cells are precursors to the Thl and Th2 subsets. A shift from a Thl to a Th2 response has been reported for HIV-1-infected patients (Kannagi et al. 1990. J. Virol. 64, 3399–3406; Walker et al. 1986. Science 234, 1563–1566; Walker et al. 1991. J. Virol. 65, 5921–5927). For this reason, the potential role of cytokines in the development of AIDS has received a great deal of attention. Interleukin (IL)-12 is a disulfide-linked, 70-kDa heterodimeric cytokine produced by antigen-presenting cells. IL-12 has a central role in the development of the Thl-type immune responses. Therefore, we investigated the ability of T-tropic HIV-1 IIIB to replicate in Thl, Th2, and Th0 T cell clones and studied the effects of IL-12 on HIV-1 replication in these cells types. These studies demonstrate several points. (1) Thl, Th2, and Th0 T cell clones support HIV-1 IIIB replication nearly equally well, and it is, therefore, unlikely that differences in ability to support HIV-1 replication can explain changes in Thl, Th2, or Th0 subtype 1 following HIV-1 infection. (2) Using this model, we show that IL-12 can inhibit HIV-1 replication, consistent with a role for IL-12 in HIV-1 replication in T cells. (3) HIV-1 can form a persistent infection in T cell clones, providing a reservoir model for study of viral sanctuary and persistence in a system closely approximating the in vivo situation.