APOPTOSIS INDUCED BY HIV-INFECTION IN H9 T-CELLS IS BLOCKED BY ICE-FAMILY PROTEASE INHIBITION BUT NOT BY A FAS(CD95) ANTAGONIST

Infection of human CD4-positive T lymphocytes by human immunodeficienc y virus type 1 (HIV-1) is thought to lead to death of infected cells b y apoptosis, although one recent report questions this conclusion, Her e we demonstrate that HIV-1-induced apoptosis of the H9 human T cell l ine is blocked by peptide inhibitors of IL-1 beta converting enzyme (I CE)-family proteases, but not by the antagonistic M3 anti-Fas Ab, Apop tosis occurred in all phases of the cell cycle, not selectively in G(2 ) as a consequence of vpr-mediated cell cycle arrest, We conclude that apoptosis accounts for all cell death related to HIV-1 infection of t he human CD4-positive cell line H9, requires an ICE-like protease but is not Fas mediated, and occurs in all phases of the cell cycle.