Human immunodeficiency virus in brain biopsies of patients with AIDS and progressive encephalopathy.

Human immunodeficiency virus (HIV) has been identified in patients with AIDS in their circulating and tissue lymphocytes and in their monocyte-macrophages, an arm of the cell-mediated immune system. We report our findings of HIV in brain biopsies. Virus was detected in oligodendroglial and astroglial cells. Virus was also present in the brain capillaries, both in lumens and at the endothelial gaps. Virus was also found in extracellular spaces. Budding forms of the developing virus and bar-shaped nucleoids of mature virus, the diagnostic hallmark of the HIV retrovirus, were identified in brain tissue of five of seven patients with AIDS studied. We believe that HIV may enter the the brain via the vascular capillaries (through the endothelial gaps), bind to brain cells containing T4 receptors, enter the cells, and replicate. There follows a reactive hyperplasia and degeneration of oligodendroglial and astroglial cells. The oligodendroglial cells are the myelin-forming cells, and thus, the result is myelin degeneration.