Decrease in neutrophils observed in vivo in psoriatics after PUVA therapy.

In 56 patients leucocyte and differential counts were done before and at weekly intervals during PUVA treatment of chronic recalcitrant psoriasis. A statistical significant (P less than 0.01) decrease in the percentage of neutrophils was observed during the first week of the PUVA therapy. This observation could be closely related to the clinical clearing of psoriasis (P = 0.02). The effect of PUVA therapy in psoriasis may be due to a decrease in the number of immunocompetent neutrophils demonstrated in psoriatic lesions.