The cell cycle in psoriasis

The cell cycle has been determined in eight in-patients with psoriasis. The cell cycle time for the germinative cell compartment has been found to be 91 h, and the turnover time for the epidermal compartment, beneath the keratin layer to be 120 h (5 days). The duration of the S phase (DNA synthesis) has been found to be 10 h, and that for mitosis 30 min. If it is accepted that the turnover time for the keratin layer is 2 days, then the turnover time for the epidermis in psoriasis is 7 days, and not 3–4 days as previously described.