Downregulation of HLA Class I Antigens in HIV-1-Infected Cells

By means of indirect immunofluorescence analysis we investigated the effect of HIV-1 infection on HLA class I surface antigens. We report here that in CD4+ HeLa cells, in H9 cells, and in peripheral T lymphocytes HLA class I antigens are downregulated following infection with HIV-1. The downregulation is effected at a posttranscriptional level since the amounts of HLA class I specific mRNA are similar in infected and uninfected cells. This phenomenon is not only correlated with the state of infection, that is, the presence of P24 of HIV-1 in the cells, but also depends on the time of infection. Upon HLA class I downregulation by HIV infection, the specific lysis of peripheral blood cells by allogeneic CTL is reduced.