SELECTIVE INDUCTION OF MONOCYTE AND NOT NEUTROPHIL-ATTRACTING CHEMOKINES AFTER INFLUENZA-A VIRUS-INFECTION

It is characteristic for virus infections that monocytes/macrophages a nd lymphocytes infiltrate infected tissue while neutrophils are absent . To understand the mechanisms selectively attracting mononuclear cell s in viral diseases, we examined in an influenza A virus model the exp ression and regulation of chemokines as candidate molecules responsibl e for the immigration of leukocytes into inflamed tissue. After influe nza A virus infection of human monocytes, a rapid expression of the mo nonuclear cell attracting CC-chemokine genes MIP-1, MCP-1, and RANTES occulted which was followed by the release of chemokine proteins. In s triking contrast to CC-chemokines, the expression of the prototype neu trophil CXC-chemoattractants IL-8 and GR O-alpha was completely suppre ssed after influenza A infection. The release of other neutrophil chem otactic factors was excluded by microchemotaxis assays. These results suggest that the virus-specific induction of mononuclear cell-attracti ng chemokines accounts for the preferential influx of mononuclear leuk ocytes into virus-infected tissue.