HLA-DR-POSITIVE DENDRITIC CELLS OF THE NORMAL HUMAN CHOROID-PLEXUS - A POTENTIAL RESERVOIR OF HIV IN THE CENTRAL-NERVOUS-SYSTEM

In a previous study of choroid plexus (CPx) from patients with the acq uired immunodeficiency syndrome (AIDS), we found a population of strom al cells infected with the human immunodeficiency virus (HIV). To dete rmine whether these represented antigen-presenting dendritic cells, we examined the phenotype of normal human choroid plexus by light and el ectron microscopy (EM) and established the HIV-infected cell type by i mmunohistochemistry in AIDS cases with HIV-infected CPx. Monoclonal an tibodies were used to detect class II major histocompatibility antigen s (MHC), S-100 and S-100 beta protein, lymphocytes, monocytes/macropha ges, and HIV glycoprotein. A variable number of stromal cells had slig htly elongated nuclei and long branching processes that were strongly immunoreactive for class II MHCs, rarely reactive for S-100 and S-100 beta and immunonegative for monocyte/macrophage markers. Phagocytic ac tivity was absent by EM and immunomarkers. They were numerous in the s ubepithelial region, and their processes occasionally extended toward the stromal capillaries or between the CPx epithelial cells. The HIV-i nfected cells were intensely immunoreactive for class II MHC markers a nd often displayed a dendritic morphology. These results document the presence of dendritic cells in the normal human CPx whose morphology a nd immunophenotype closely resemble those of DCs elsewhere in the body , They also show that these immunoreactive MHC class II cells are the cell type infected by HIV. We suggest that the functional activity of the CPx DCs is similar to that of antigen-presenting dendritic cells e lsewhere in the body. This includes the potential to harbor HIV during the prolonged period of clinical latency, acting as a central nervous system reservoir of infection before the onset of AIDS. Copyright (C) 1998 by W.B. Saunders Company.