Defective calcium transport in vitiliginous melanocytes.

Melanocytes were successfully established from involved and uninvolved skin of a patient with acute acrofacial vitiligo. Cells from involved epidermis showed a fivefold decrease in the rate of radiolabelled 45Ca uptake compared with uninvolved and control cells. These results are similar to previous findings in keratinocytes from involved skin in patients with vitiligo. Since 6-biopterin is cytotoxic to melanocytes and calcium controls the redox status of the 6-biopterin/(6R)5, 6, 7, 8-tetrahydrobiopterin equilibrium via the thioredoxin reductase/thioredoxin system, these results underline the importance of this electron transfer system for both melanocyte function and survival.