Host defense response to cytomegalovirus in the central nervous system. Predominance of the monocyte.

Cytomegalovirus (CMV) infection of the brain is common in AIDS; however, little is known of the host defense response to CMV in the central nervous system (CNS). A guinea pig model was developed to study this problem. In the present studies the percentages of T cells and monocytes invading the leptomeninges during the course of acute CMV infection were compared. In addition, qualitative observations on parenchymal infiltrates were made. Such studies have not been performed previously in CMV infection of the CNS. Monocytes, defined cytochemically, predominated in the leptomeninges and in parenchymal foci. In contrast, T cells, defined immunohistologically, were found in a low percentage in the leptomeningeal reaction and only rarely in the parenchyma. These novel results differ significantly from other viral infections in which the T cell predominates in the leptomeningeal response and plays a major role in the parenchyma.