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 (HIV-1) 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 Th1, Th2, and Th0, which differ in their cytokine profile. Th1 cells produce cytokines that favor cel l-mediated immune responses, whereas Th2 cells produce cytokines that favor humoral immunity. Th0 cells are precursors to the Th1 and Th2 su bsets. A shift from a Th1 to a Th2 response has been reported for HIV- 1-infected patients (Kannagi et al. 1990. J. Virol. 64, 3399-3406; Wal ker 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 t he development of AIDS has received a great deal of attention. Interle ukin (IL)-12 is a disulfide-linked, 70-kDa heterodimeric cytokine prod uced by antigen-presenting cells. IL-12 has a central role in the deve lopment of the Th1-type immune responses. Therefore, we investigated t he ability of T-tropic HIV-1 IIIB to replicate in Th1, Th2, and Th0 T cell clones and studied the effects of IL-12 on HIV-1 replication in t hese cells types. These studies demonstrate several points. (1) Th1, T h2, and Th0 T cell clones support HIV-1 IIIB replication nearly equall y well, and it is, therefore, unlikely that differences in ability to support HIV-1 replication can explain changes in Th1, Th2, or Th0 subt ype 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 infecti on in T cell clones, providing a reservoir model for study of viral sa nctuary and persistence in a system closely approximating the in vivo situation.