Interleukin-4 is needed for the infection of monocytes by human cytomegalovirus

Objective: We studied the ability of human cytomegalovirus (HCMV) to infect peripheral blood mononuclear cells (PBMC) pretreated with or without Th2-c ytokine interleukin-4 (IL-4) in vitro. Methods: Adherent cells and nonadher ent cells were obtained from PBMC. We inoculated these cells with HCMV at c oncentrations ranging from 0 to 10 ng/ml of IL-4. Immediate-early antigen-1 (IE-1) and glycoprotein H (gH) mRNAs were detected using the reverse-trans cription polymerase chain reaction. Results: IE-1 and gH mRNAs could be det ected in monocytes pretreated with IL-4. In contrast, no IE-1 mRNA was dete cted in monocytes pretreated without IL-4. We tested whether higher infecti ous titers could result in the infection of monocytes whether or not they w ere pretreated with IL-4. However, no IE-1 mRNA was detected in the monocyt es not pretreated with IL-4. To elucidate how HCMV-infected monocytes affec t lung tissue, human embryonic lung fibroblasts MRC-5 were cocultured with HCMV-infected monocytes. The cytopathic effects of HCMV were observed micro scopically and was confirmed by direct immunoperoxidase staining with a hum an monoclonal antibody against the HCMV IE-1. Conclusion: Our data strongly suggest that the ability of HCMV to infect monocytes may correlate with th e presence of IL-4. Copyright (C) 2001 S. Karger AG, Basel.