CD4 and AIDS: Early studies into AIDS pathogenesis reported that apoptosis of CD8+ and CD4+ T lymphocytes has a key role in disease progression and that apoptosis of neuronal elements may also lead to the neuronal cell loss noted in patients.42–44 Increased apoptosis of neurons, astrocytes and microvascular endothelial cells also occurred in the CNS of macaques infected with a neurovirulent strain of simian immunodeficiency virus.45 Consistent with these observations, we showed HIV-1-mediated apoptosis of astrocytes that was further enhanced by EtOH.