The involvement of the cerebral cortex in human immunodeficiency virus encephalopathy: a morphological and immunohistochemical study.

The encephalopathy resulting from direct infection of the brain by human immunodeficiency virus (HIV), which correlates clinically with the AIDS dementia complex, has been reported as being localized to the white matter where it induces myelin loss, gliosis and perivascular infiltration by mononuclear macrophages and multinucleated giant cells. Damage to the cortical grey matter in HIV encephalopathy was investigated in nine randomly selected HIV-positive cases with or without clinical or morphological evidence of encephalopathy and in five age-matched controls, using routine histology and immunohistochemical methods [glial fibrillary acidic protein (GFAP), microglia and HIV antibodies]. Increased numbers of GFAP-expressing astrocytes and Ricinus communis agglutinin 1-120-expressing microglial cells were found in all the HIV-positive cases (including asymptomatic) and their severity could be correlated with the severity of the encephalopathy in the white matter; the increase in number of cells expressing GFAP was diffuse and the intensity of the staining higher than that of microglial cells. The subpial region was the most severely involved. It is suggested that involvement of the cortical grey matter is more common in HIV infection than previously suspected and that clinical evidence of a dementing process in AIDS is not necessarily due only to white matter lesions.