Depression of Human Monocyte Chemotaxis by Herpes Simplex and Influenza Viruses

Abstract

Abstract To determine the effect of virus infection on monocyte chemotaxis, we isolated mononuclear leukocytes (MNL) from human peripheral blood on a Ficoll-Hypaque gradient and quantitated the chemotactic responsiveness in modified Boyden chambers. The MNL were exposed to herpes simplex (7 plaque-forming units/MNL) or influenza virus (103.0 hemagglutinin units/106.7 MNL) before quantification of chemotactic responsiveness of the cells to a chemotactic lymphokine. Incubation of these viruses with human MNL depressed monocyte chemotaxis by 62 to 85% (p <0.001) as compared to MNL incubated with non-infectious (UV-irradiated) viruses or a control tissue culture preparation. Similar amounts of vaccinia, polio, and reovirus were not inhibitory, and suggested that the inhibition was not a universal effect of viruses. Depressed chemotaxis was not caused by virus-induced cytotoxicity (as measured by trypan blue exclusion) since greater than 95% of the MNL were viable at the end of the assay period. The data suggest that one mechanism for the depression of cell-mediated immunity seen in certain viral infections can be due to the ability of viruses to inhibit monocyte chemotactic responsiveness.