Developmental Immunology, 1998, Vol. 6, pp. 105-110 Reprints available directly from the publisher Photocopying permitted by license only (C) 1998 OPA (Overseas Publishers Association) N.V. Published by license under the Harwood Academic Publishers imprint, part of the Gordon and Breach Publishing Group Printed in Malaysia Minireview Hormonal Regulation of Uterine Macrophages JOAN S. HUNTb*, LANCE MILLERb and JERALYN SUE PLATT aDepartment of Anatomy and Cell Biology; bDepartment of Pathology and Laboratory Medicine University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, Kansas 66160-7400 (Received 30 May 1997; In final form 30 May 1997) Macrophages are major cellular inhabitants of cycling and pregnant mammalian uteri. Their densities and patterns of tissue distribution in this organ fluctuate in concert with levels of circulating female sex steroid hormones, estrogens and progesterone, and their production of various effector molecules also may be hormonally regulated. Hormonal control may be achieved by direct binding to receptors or by indirect pathways where hormones modulate production of various autocrine and paracrine cytokines and growth factors that then target to resident macrophages and influence their secretory profiles. In this paper, we marshall evidence supporting the concept that progesterone acts as a powerful negative regulator of these versatile cells, reducing their migration into the uterus and impairing their ability to produce potent effector molecules such as nitric oxide that could interfere with the success of pregnancy. Keywords: Estrogen, interferon-y, macrophage, mouse, nitric oxide, progesterone INTRODUCTION Although macrophages have long been recognized as influencing their migration, differentiation, and major cellular inhabitants of cycling and pregnant activation in the uterus have been investigated; and mammalian uteri, nearly all of the studies that have some information on their secretory profiles has been established the fundamental characteristics of these generated. remarkable cells have been reported within the last The studies done thus far indicate that essentially decade and a half (reviewed by Hunt, 1989; Hunt and all aspects of macrophages in the uterus are governed Pollard, 1992). Macrophage densities and distribu- directly or indirectly by female hormones, estrogens *Corresponding author. Present address: Department of Anatomy and Cell Biology, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160-7400. 105 tional patterns within cycling and pregnant uteri of rodents and women have been mapped; conditions