Interference with human immunodeficiency virus (HIV) replication by CD8+ T cells in peripheral blood leukocytes of asymptomatic HIV carriers in vitro

A long asymptomatic period is one of the characteristics of human immunodeficiency virus (HIV) infection, despite its fatal consequences. Antiviral defense in HIV-infected individuals controls viral replication during this period. In the present study, we demonstrate that peripheral blood leukocytes (PBL) of asymptomatic HIV-1 carriers, following exogenous HIV-1 infection in vitro, do not support viral replication. These cells do not produce detectable amounts of reverse transcriptase or accumulate unintegrated proviral DNA. This is a striking contrast to the behavior of HIV-1-infected PBL of seronegative individuals, which produce large amounts of RT and unintegrated DNA. Such resistance to HIV-1 replication is not seen in PBL of patients with advanced disease. Since the binding of HIV-1 to CD4 molecule is not impaired in PBL of asymptomatic carriers, the interference with HIV replication must occur after the stage of virus binding. PBL lose their resistance when CD8+ lymphocytes are removed. In addition, these PBL are not resistant to an exogenous infection with HIV-2. These observations suggest that certain populations of CD8+ lymphocytes of asymptomatic HIV-1 carriers operate on the target cells in PBL to block viral replication in an HIV-1-specific manner. Such CD8+ lymphocyte-mediated interference with HIV replication could play an important role in the maintenance of the period of disease latency.