CD4 and Kaposi's sarcoma: Disease pathogenesis in AIDS-KS is linked to depletion of CD4+ T cells and the loss of KSHV-specific CD8+ cytotoxic T lymphocyte (CTL) responses 8, and treatment of AIDS-KS patients with highly active antiretroviral therapy (HAART) frequently induces KS remission 11 in association with recovery of anti-KSHV CTL responses 6.