Development of an in vitro test system with human skin cells for evaluation of phototoxicity.

Photosensitizing compounds may cause severe skin reactions after appropriate light exposure. On the cellular level this cutaneous in vivo response can be demonstrated by an in vitro model system with adequate target cells of human skin. Normal keratinocytes and fibroblasts were used to establish a predictive assay for phototoxic compounds.

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.