Defective calcium uptake in keratinocyte cell cultures from vitiliginous skin

Summary ⁴⁵Ca²⁺ has been used to measure the 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 some more light on the etiology of this disorder.