Effects of 17 beta-estradiol on circulating adhesion molecules.
The effects of 17 beta-estradiol (E2) on the serum levels of the circulating endothelial-leukocyte, intercellular, and vascular adhesion molecules [ELAM-1, ICAM-1 (CD54), and VCAM-1] were evaluated in healthy male volunteers after single im injection of 10 mg E2 valerate. In addition, a time course of the effects of E2 on circulating adhesion molecules (AMs), cortisol serum levels, differential blood counts, and surface expression of the lymphocyte function-associated antigen-1 (CD11a/CD18), CD3, CD4, CD19, and CD25 on leukocytes was studied in another group of volunteers. A 5% decrease in circulating ICAM-1 (P = 0.045 vs. placebo) was found when a single time point (96 h after E2 injection) was studied. However, this decrease was smaller than the intrasubject (day to day) variability observed, and there was no consistent and time-dependent effect of E2 on circulating AMs. Circulating neutrophils increased 2.3-fold over baseline after E2 treatment (P = 0.0008 vs. placebo). The mean coefficients of variation for the intrasubject (day to day) and intersubject variability of circulating AMs were between 5.4-7.5% and 20-29%, respectively. Our findings indicate that the effect of E2 on circulating AMs is not distinguishable from the intrasubject variability observed after placebo treatment. Thus, an effect of E2 on adhesion molecules is unlikely to contribute to the antiatherogenic-cardioprotective effect of E2. The pronounced E2-mediated increase in neutrophils deserves further studies to elucidate its (patho-)physiological implications.