Immunologic implications of PUVA therapy in psoriasis vulgaris

Summary During the combined effects of psoralen and UVA irradiation (PUVA therapy) a significant decrease (P<0.005 in T cells has been noted in 10 psoriasis patients and 10 healthy controls especially after four exposures. Based on the fact that the total number of circulating lymphocytes of the patients and the PUVA-treated healthy controls remained within the normal range, this decrease may be due to temporary physicochemical changes of the membranes of these cells but not to T cell lysis. After eight exposures these decreased T cell values returned to starting range. The starting T cell range in psoriasis patients is significantly lower (P<0.005) compared to that of healthy controls.It is of importance that before PUVA therapy in all the patients antibodies reactive with a basal cell nuclear antigen belonging to the four main Ig classes (IgM, IgD, IgE, and IgA) could be removed from the membrane of circulating lymphocytes by means of acid elution. In contrast, mainly the IgA antinuclear basal cell antibody could be eluted from circulating PMN leukocytes in the patients under investigation. After eight PUVA exposures, however, corresponding antibodies, belonging to the three main Ig classes (IgM, IgD and IgE) could also be eluted from the membranes of circulating PMN-leukocytes of the same patients. This implies an exchange of molecules during photochemotherapy. Finally, it could be shown that after effective PUVA therapy antinuclear basal cell antibodies of the psoriasis patients under study were reactive not only with the nuclei of the basal cell layer but also with almost all the nucleic of the epidermis of the uninvolved and lesional skin. The latter finding points to the fact that PUVA treatment causes at least antigenic changes of nuclear proteins in all the nuclei of the epidermis of the PUVA treated skin. Moreover, inflammatory cells with Fab fragments within the cells present in the lesional skin before PUVA disappear during this treatment.Based on a poster session presented at the occasion of the seventh joint meeting of the ESDR, Amsterdam, The Netherlands, May 1977