Effects of 8-methoxypsoralen (8-MOP) and UVA on human lymphocytes

Abstract

Peripheral lymphocytes of 37 psoriatic patients are tested before and under PUVA treatment using as parameter the non specific stimulation effect of HgCl2 (10 microgram/ml) in culture, measuring the 3H-thymidine incorporation after the last 16 h of a 5-days culture. Oral 8-MOP in therapeutic doses is decreasing the lymphocyte stimulation as well as 8-MOP together with UVA irradiation during the first week of treatment. After 1 week, the stimulation is, on the contrary, significantly enhanced after irradiation. Lymphocytes isolated by centrifugation over Lymphoprep are submitted to PUVA conditions in petri dishes (Hank's solution 8-MOP 1 microgram/ml, irradiation with 350 nm, 93-372 mJ/cm2). The total cell number, the E-rosette formation (as marker for T-lymphocytes) and the EAC-rosette formation (as marker for B-lymphocytes) are determined. PUVA conditions have an energy dependent decreasing effect on the cell number, while the T- and B-cell proportions remain constant. UVA irradiation alone has such an effect only with high energies. 8-MOP without UVA has no significant influence on the cell number.