Effect of 8-methoxypsoralen plus UVA (PUVA) on lymphocyte transformation and T cells in psoriatic patients

Abstract

SUMMARY The peripheral blood lympochytes of the psoriatic patients studied initially showed a normal response to phytohaemagglutinin (PHA) and to purified protein derivative of turberculin (PPD) in a microculture using whole blood, but a lower than normal response to a high concentration of concanavalin A (Con A). The initial level of E-rosette-forming T cells in psoriatic patients (51.3%) was significantly lower than that in healthy controls (66.7%). A single exposure to 8-methoxypsoralen (8-MOP) and UVA light (PUVA) did not suppress the lymphocyte responses to PHA, Con A or PPD, rather the responses showed a tendency to be slightly increased. Similarly, no changes in the mitogen responses of peripheral blood lymphocytes were recorded during or after 12 weeks PUVA therapy for psoriasis. The lymphocytes still showed a weaker than normal response to a high concentration of Con A. However, the percentage of E-rosette-forming T cells in the peripheral blood increased from 51.3% to 62.8% after 12 weeks PUVA therapy. The low initial level of E-rosette-forming T cells was found to correlate more closely with the activity than with the extent of the disease. The increase found in the E-rosette-forming cells during PUVA therapy did not correlate with the improvement of the psoriatic lesions. The low response of peripheral blood lymphocytes of psoriatic patients to a high concentration of Con A correlated with the age of the patients but not with the activity or extent of the disease.