Increased in vitro expression of beta 2-adrenoceptors in differentiating lesional keratinocytes of vitiligo patients.

Keratinocytes were established in serum-free culture medium from lesional and nonlesional skin of a patient with vitiligo (skin type III) and from an age-matched healthy control subject. Both differentiating and undifferentiated cells were examined for the presence of beta 2-adrenoceptors in culture medium containing either low (0.1 x 10(-3) M) or high (1.5 x 10(-3) M) calcium concentrations. Binding experiments were performed with saturating levels of radiolabeled (--)-[3H] CGP 12177, a nonselective beta-adrenergic antagonist. Controls for nonspecific binding were determined by the addition of the beta-adrenergic antagonist, propranolol (5 mumol), before the introduction of (--)-[3H] CGP 12177 to cell cultures. Undifferentiated keratinocytes yielded the highest expression of beta 2-adrenoceptors, whereas differentiating keratinocytes grown in medium with a low calcium concentration (0.1 x 10(-3) M) had a significantly lower expression of receptors with the exception of vitiliginous cells, which retained high densities of receptors, similar to undifferentiated cells. In addition, these vitiliginous keratinocytes showed a defect in 45calcium uptake. In contrast, differentiated keratinocytes from all three cell strains, grown in medium containing a high calcium concentration (1.5 x 10(-3) M) revealed a significantly lower receptor density compared to undifferentiated cells. This finding identified the importance of the extracellular calcium concentration in the expression of beta 2-adrenoceptors.(ABSTRACT TRUNCATED AT 250 WORDS)