Differential effects of parainfluenza virus type 3 on human monocytes and dendritic cells

To understand the lack of protective immunity observed after infection with parainfluenza virus type 3 (PIV3), we tested the effect of the virus on hu man monocytes and monocyte-derived immature dendritic calls (DCs). Expressi on of viral antigens on the cell surfaces correlated with replication of th e virus, which was marginal in monocytes but extremely efficient in DCs. Th e virus increased monocyte survival at least in pa rt through the productio n of granulocyte-macrophage colony-stimulating factor but, in contrast, acc elerated DC apoptosis. In addition, PIV3 infection failed to activate monoc ytes but induced maturation of DCs with increased expression of CD54, HLA-D R, CD86, and CD83 and production of bioactive IL-12. However, PIV3-infected DCs demonstrated low stimulatory properties in DC-T cell cocultures, a fin ding that could not be attributed to the production of infectious virus or IL-10. These results demonstrate for the first time that PIV3 dramatically modifies the survival and/or the function of antigen-presenting cells and m ight therefore prevent the development of efficient antiviral immune respon ses. (C) 2001 Academic Press.