[Cell kinetic effects of a single PUVA treatment on rapidly proliferating epidermis of the stripped skin of guinea pigs].

This study investigated the cell kinetic effects of a single treatment with PUVA on guinea pig epidermis after tape stripping. Flow cytometry was used to determine the proportion of cells in S phase and G2 + M phase. Bromodeoxyuridine incorporation was used to determine the labeling index. Conventional histological techniques were used to observe the mitotic index. An initial decrease followed by a subsequent significant increase compared to the non-PUVA-treated controls was observed in all parameters studied except the mitotic index, which was below or around the control level until 168 hours after the treatment with PUVA. The results obtained in this study suggest that PUVA induces a partial blocking at G1-S boundary for short duration, and that when the partial G1 block is released, then the cells of stimulated epidermis enter DNA synthesis and pass through the S phase to the G2 phase in partial synchrony. It is also suggested that PUVA blocks the passage of cells from the G2 phase to mitosis, resulting in an long-lasting accumulation of cells in the G2 phase.