HIV-INFECTION OF HUMAN CHOROID-PLEXUS - A POSSIBLE MECHANISM OF VIRALENTRY INTO THE CNS

The present study examines the hypothesis that HIV infection of the ch oroid plexus (CPx) may be an important site of viral entry into the br ain. Formalin-fixed, paraffin-embedded CPx was obtained from 25 patien ts with AIDS and 13 nonAIDS patients and was processed for light micro scopy and for immunohistochemical detection of HIV gp41, T and B lymph ocytes, monocytes/macrophages and endothelial cells. Eleven of the 13 nonAIDS CPx were normal and 2 contained inflammatory foci of undetermi ned etiology. The stroma contained T lymphocytes in all and monocytes in 22%; B lymphocytes and HIV antigen were absent. Choroid plexus of t he AIDS cases contained opportunistic infections or lymphoma in 12 and inflammatory foci alone in 6; 7 were normal. T lymphocytes were prese nt in 70% and monocytes in 50%. In addition to the stromal localizatio n, monocytes also were present in supra-epithelial regions and within or adjacent to the capillary endothelium. HIV-positive cells in the CP x were found in 11 cases (44%) and in the supra-epithelial area in ano ther 2. Their presence correlated with neither infection nor lymphoma of the CPx or brain. They were situated in the stroma, supra-epithelia l region and (rarely) capillary endothelium. Immunohistochemistry on s erial sections identified the HIV-infected cells as monocytes, includi ng those by capillary endothelium and in supra-epithelial areas. The s tudy demonstrates that the CPx contains HIV-infected monocytes in almo st half of the cases. Their apposition to endothelium suggests hematog enous origin. These results support the hypothesis that HIV encephalit is may develop from CPx infection.