Perivascular Location of a Chemokine Interleukin-8 in Human Endometrium: a Preliminary Report

The cytokine interleukin-8 (IL-8) is capable of inducing selective neutrophil chemotaxis and activation and has been postulated as the signal for neutrophil recruitment and activation in reproductive tissues. The aim of this study was to examine the localization of IL-8 in non-pregnant human endometrium in view of its potential as a local modulator of endometrial function. Endometrial biopsies (proliferative, n = 8; secretory, n = 7) from 15 subjects were available for immunolocalization of IL-8. Primary antibody (rabbit polyclonal against IL-8) application was followed by either a horseradish peroxidase streptavidin detection system (proliferative, n = 5; secretory, n = 4) or an avidin-biotin alkaline phosphatase detection method (proliferative, n = 3; secretory, n = 3). All endometrial biopsies showed heterogeneous positive staining for IL-8 in association with blood vessels in both proliferative and secretory phase biopsies. The immunostaining was apparently not associated with endothelial cells but rather appeared to be associated with the smooth muscle layer of arterioles. Secretory phase biopsies exhibited immunoreactivity in association with small blood vessels and spiral arterioles. The perivascular location of IL-8 throughout the stages of the human menstrual cycle is consistent with its proposed biological role as a modulator of endometrial function, especially synergism with prostaglandin E and the transmigration of leukocytes.