Transient impairment of peripheral blood lymphocyte function during PUVA therapy.

Three parameters of immune function--enumeration of circulating T and B lymphocytes and response of lymphocytes to graduated doses of phytohaemagglutinin (PHA)--were examined serially in eleven patients with psoriasis before, during, and after an intensive course of PUVA therapy. A trend was detected for the lymphocyte response to PHA to fall during the first week of treatment and then rise back towards the pre-treatment level. No alteration was found in the percentage or absolute numbers of circulating T and B lymphocytes. This study shows that routine PUVA therapy can induce an alteration in immune function but that this alteration is slight and short-lived.