Corticoids and cultured human epidermal keratinocytes: Specific intracellular binding and clinical efficacy

Abstract

Cytosol of cultured human epidermal keratinocytes contains macromolecules, that bind corticoids with high affinity. Binding constants were in the same range for cultured keratinocytes originating from different individuals and did not change during serial cell cultivation. At 0°C and using 3H-triamcinolone acetonide as ligand, we obtained the following values: apparent B(max) = 160-250 fmoles/mg protein and K(diss) = 3.1-5.0 nM; with 3H-dexamethasone B(max) = 200-350 fmoles/mg protein, K(diss) = 6.0-11.1 nM, and with 3H-hydrocortisone B(max) = 140-220 fmoles/mg protein, K(diss) = 17-25 nM. There was an indication that the binding capacity of the receptor system is higher the younger the age of the skin donor. A number of steroids and corticoids commonly used in dermatological practice were tested with respect to displacement of 3H-triamcinolone acetonide, 3H-dexamethasone, and 3H-hydrocortisone from binding sites in cytosol. Good correlation between clinical efficacy and specific binding was observed for all 3 ligands. Other steroids such as 17-β estradiol and nandrolone did not show any affinity for the corticoid binding system. Progesterone displaced 3H-corticoids from their binding sites, but the IC50 was of one order of magnitude larger.