UPTAKE OF 3H-CORTISOL BY RABBIT POLYMORPHONUCLEAR LEUKOCYTES IN VITRO

Abstract

ABSTRACT The in vitro uptake of 3H-cortisol by rabbit polymorphonuclear leukocytes (PMN) was studied. The 3H-cortisol concentration in the incubation medium was 1 ng/ml. By adding non-radioactive cortisol to the medium the 3H-cortisol uptake could be depressed, indicating a saturable component in the uptake. At 37°C the uptake was maximal within 10 minutes. The uptake was also depressed by progesterone, 17α-OH-progesterone, corticosterone and to a lesser degree by testosterone and 17β-oestradiol. Chromatography showed that almost all the 3H-cortisol was bound in an unchanged form. The uptake and retention were temperature-sensitive. Contrary to the cortisol-binding site of transcortin, the saturable binding of 3H-cortisol in the PMN's was not destroyed by trypsin. The 3H-cortisol uptake in erythrocytes was also studied; it was very small and showed no saturable component. The saturable 3H-cortisol uptake in the PMN's might be related to a special sensitivity to this hormone.