Defective calcium uptake in keratinocyte cell cultures from vitiliginous skin.

45Ca2+ has been used to measure kinetics for the uptake, efflux, and "steady state" of this regulatory cation in keratinocytes grown from the involved and uninvolved skin of one donor (JM) with vitiligo. Cells grown from uninvolved skin yielded a very rapid uptake and efflux of this isotope before reaching "steady state". A similar profile has been found for keratinocytes from normal healthy adult controls. However, cells established from vitiliginous skin showed a slow uptake of 45Ca2+ before reaching the same "steady state" as the controls. 45Ca2+ efflux has not been observed in vitiliginous keratinocytes. Furthermore, vitiliginous keratinocytes yielded a higher concentration of extracellular bound 45Ca2+ compared with keratinocytes from uninvolved skin. Since Ca2+ has been found to be an allosteric inhibitor of membrane-associated thioredoxin reductase, this defect in Ca2+ transport may explain the proposed breakdown in free radical defense in vitiligo. These findings may also shed more light on the etiology of this disorder.