Contribution to the regulation of virus replication in cells latently infected with human immunodeficiency virus 1

Monocytes/macrophages have been known to play an important role in the initiation and propagation of human immunodeficiency virus 1 (HIV-1) infection. To analyze the function of these cells during the clinical asymptomatic period of infection, we examined the effect of murine peritoneal macrophages and human peripheral blood macrophages on two cell lines latently infected with HIV-1, a promonocytic cell line, U1, and a T-cell line, ACH-2. Monokines of the murine peritoneal macrophages induced significant viral expression in U1, but not in ACH-2 cells. Experiments employing transient transfection of U937 and CEM cells with HIV long terminal repeat (LTR)-chloramphenicol acetyl transferase (CAT) plasmids indicated that the effect of these monokines was due to specific activation of the HIV LTR. In contrast, supernatants of human macrophages induced viral expression in both ACH-2 and U1 cells. These results suggest that several monokines are active in regulating the transition from the clinical asymptomatic period of HIV infection to progression to acquired immunodeficiency syndrome (AIDS).