HIV encephalopathy and lymphadenopathy: cells associated with viral antigens.

HIV associated subacute, micronodular encephalitis and lymphadenopathy were compared with regard to demonstrable HIV antigens and characterization of HIV antigen expressing cells. In the brain, both gag- and env-coded antigens were confined to cells of micronodular lesions with immunophenotype of monocyte/macrophages (KiM6+, 9.4+, CD4+/-). The micronodular lesions were also infiltrated by some lymphoid cells, predominantly CD8+. In lymphadenopathic nodes, gag-encoded antigens were demonstrable almost exclusively in follicles/germinal centres in association with follicular dendritic cells, whereas env-antigens usually were not found. Follicular involution was related to destruction of follicular dendritic cells and infiltration of CD8+ lymphocytes within the germinal centres. During follicular involution, HIV-gag antigens diminished in parallel with destruction of the network of dendritic reticulum cells. These findings indicate important tissue related differences in HIV expression. In addition, a possible participation of CD8+ cells in the pathogenesis of HIV induced tissue lesions is suggested.