GESTATION-RELATED EXPRESSION OF THE INTERFERON-GAMMA RECEPTOR GENE INMOUSE UTERINE AND EMBRYONIC HEMATOPOIETIC-CELLS

Macrophages and natural killer (NK)-like cells are the major hematopoi etic cell populations in the cycling and pregnant mouse uterus and are also found in the embryo. In order to evaluate potential receptivity of these cells to interferon-gamma (IFN-gamma), tissues taken from cyc ling and pregnant mice were tested for IFN-gamma receptor (IFN-gamma R ) mRNA and protein. Macrophages were identified immunohistochemically by using the specific monoclonal antibody F4/80. NK cells were identif ied by their large size, distinctive intracellular granules, and bindi ng of a monoclonal antibody to the common leukocyte antigen. In cyclin g uteri, the abundance of IFN-gamma R mRNA relative to an invariant me ssage (glyceraldehyde-3-phosphate dehydrogenase) increased during prog ression of the hormonally regulated estrous cycle. IPN-gamma R mRNA in situ hybridization signals were slightly higher in macrophage-like th an in other types of endometrial stromal cells. In pregnant uteri, the highest proportions of IFN-gamma R mRNB were observed at gestation da y (g.d.) 16. Specific message and protein were present in uterine macr ophages by p.d. 7 and in NK cells by g.d. 9. IFN-gamma R expression in both lineages remained stable through the balance of pregnancy. In em bryos, IFN-gamma R mRNA increased between g.d. 14 and 16. Specific tra nscripts were present in many cells at g.d. 14, but none were detected in embryonic liver macrophages until g.d. 16. The results of this stu dy; suggest relationships between IFN-gamma R expression and ovarian h ormones as well as cell maturation and support the postulate that IFN- gamma receptor-ligand interactions may improve the ability of uterine and embryonic hematopoietic cells to perform specific tasks during ges tation.