STUDIES ON THE BINDING OF CORTISOL-4-14C BY HUMAN LEUCOCYTES IN VITRO

Abstract

ABSTRACT The amount of cortisol-4-14C bound by human leucocytes in a non-protein balanced salt solution was found to have a linear relationship to the concentration of cortisol-4-14C for a given number of leucocytes, and a linear relationship to the number of leucocytes for a given concentration of cortisol-4-14C. The binding was not affected by 10−3 m concentrations of arsenate, cyanide, fluoroacetate, dinitrophenol, fluoride, methylene blue, malonate, hydroxylamine or semicarbazide. The binding of cortisol-4-14C by leucocytes was found to be temperature dependent. At 0° C, no binding of cortisol-4-14C was detected. From 10° to 80°, each 10° rise resulted in an approximately two fold increase in amount of cortisol-4-14C bound, but no further increase occurred between 80° and 100°. Experiments in which leucocytes were exposed to various specific temperatures without cortisol, and then incubated with cortisol-4-14C at 37° revealed that exposure to lower temperatures had no effect on the uptake of cortisol-4-14C at 37°, but that exposure to higher temperatures had increased the binding of cortisol-4-14C at 37°. The addition of either human plasma or human serum albumin to the incubation medium markedly reduced the uptake of cortisol-4-14C by the leucocytes. Approximately 2/3 of the cortisol-4-14C (or metabolite) was removed upon incubation for 30 minutes at 37° C with either Hanks's solution (non-protein), plasma or serum albumin.