The Effect of Systemic PUVA on the Proliferation of Melanocytes and the Titer of Anti - Pigment Cell Autoantibodies in Vitiligo Patients / 대한피부과학회지

ABSTRACT

BACKGROUND: PUVA has been used effectively in the treat,ment of vitiligo, but the mechanism by which PUVA stimulat.es melanocyte proliferation in vitiligo is not known. Several mechanisms have been suggested to be involved in the process of repigmentation of vitiligo. First, UV light, with or without psoralen, directly stimulates the proliferation of melanocytes. Secondly, PUVA may act. on epidermal keratinocytes or dermal components to stimulate t,hem to release certain melanocyte growth st,inulation factors that enhance the proliferation of melanocytes in depigmented lesions. Thirdly, PUVA irnmunologically leads to the impairment of epidermal Langerhans cell function and alteration of circulating T and B cell function, which results in the suppression of the stimuli is for rnelanocyte destruction during the therapy. OBJECTIVE: To test, th hypothesis that PUVA induced repigmentation in vitiligo results from the stimulation of growth factors that induce melanocyte proliferation, and that PUVA may suppress the immune reacticin to melanocytes, especially in autoantibody synt,hesis, we examined the effects of sera on the growth of epidermal melanocytes and control cells, and t,he incidence of antibodies to melanocyte and melanoma cells(SK-Mel 2~3) in the sera of patients with vitiligo. We also had normal control individuals and studied the changes of the antibody titer in the sera of patients with vitiligo. METHODS: The rate of H thymidine uptake was estimat,ed in cultured melanocytes and fibroblasts t,reated by patients sera before and after PUVA treatment. SDS-PAGE and immunoblotting analysis were used to idcntify anti pigment cell autoantibodies and were compared to the titers of autoantibodies after PUVA. RESULTS: 1. Melanocyte and fibrablast proliferation was increased by PUVA treated sera. Their proliferation was in proportion to the duration of the PUVA treatment. Melanocytes proliferated more than fibroblasts. 2. Significant differences between vitiligo patients and normal controls were found in the inci dence of anti-pigment cell antibodies. The antibodies were predominantly directed to melanocyte antigens of 110 kD, 65 kD, 45 kD and melanoma cell antigens of 110 kD, 103 kD, 88kD, 70 kD, 56 kD, 41 kD. 3. The titer of anti piment cell antibodies showed a tendency to decrease after PUVA treat- ment in most patients regardless of clinical improvement. Conclusion ; PUVA treated sera induced proliferation of melanocytes and fibroblasts and the production of aut,oantibodies was suppressed against pigment cell antigens through irnmunosuppression, which might help in the repigmentation of vitiligo.