Puva photohyposensitization in polymorphous light eruptions: evaluation of systemic immunological factors.

Systemic immunological parameters were monitored in 26 polymorphous light eruption (PMLE) patients prior to, during and after photochemotherapy by either an oral or topical (bath) regimen. Pre-therapy investigations showed a normal immune status as regards the numbers of peripheral T-cells as well as the response of peripheral blood lymphocytes to PHA, ConA and PPD. Measurement of the immunological parameters after four PUVA exposures revealed a statistically significant increase in the lymphocyte PHA responses. After the completion of a PUVA course of some 20 irradiations, normalized PHA responses were found. The total lymphocyte count increased slightly during the treatment but the relative numbers of T- and B-cells changed very little. The immunological changes observed were of only moderate strength and it remains doubtful whether they play any major role in the hyposensitizing effect of PUVA irradiations in PMLE.