Macrophages: a source of luteotropic cybernins.
ABSTRACT A macrophage homogenate contained substances which stimulated primary cultures of mouse granulosa cells to secrete more progesterone. The response to the luteotropic substances was similar to that observed when intact macrophages were co-cultured with granulosa cells. The bioactive polypeptides present in cytosolic and particulate fractions of cell homogenates were non-dialyzable, heat labile and trypsin sensitive. When the surface of intact macrophages was treated with trypsin there was a loss of activity from the particulate fraction suggesting that some luteotropic proteins reside on the plasma membrane of mononuclear phagocytes. Treatment of macrophages with Con A but not the succinyl derivative of the lectin caused a release of luteotropic proteins with apparent molecular weights of 26,000 and 41,000. These findings in conjunction with our prior observation that macrophages must contact granulosa cells to stimulate progesterone secretion suggest that aggregation of mononuclear cell surface proteins may occur when the two cells interact thus resulting in the expression of luteotropic activity. Hence, it appears that macrophages which are found within corpus luteum may be a source of ovarian cybernins. This is the first description that a cell of the immune system can communicate at the molecular level with a steroid secreting cell of the ovary.
- SourceAvailable from: William Colin Duncan[Show abstract] [Hide abstract]
ABSTRACT: It has been shown that immune cells, particularly macrophages, accumulate in the corpus luteum during luteolysis. This study aimed to investigate the effect of maternal recognition of pregnancy on the localization and numbers of macrophages in the human corpus luteum. Corpora lutea (n = 12) were obtained from normally cycling women at the time of hysterectomy and were dated on the basis of serial urinary luteinizing hormone (LH) estimation. In addition, corpora lutea (n = 4) were collected from women who had received daily doubling doses of human chorionic gonadotrophin (HCG) to mimic the hormonal changes of early pregnancy. Macrophages were localized by immunohistochemistry using an anti-CD68 antibody. Steroidogenic cells, steroidogenic cells of thecal origin and endothelial cells were identified on serial sections by immunohistochemistry for 3beta-hydroxysteroid dehydrogenase, 17alpha-hydroxylase and von Willebrand factor, respectively. The luteal cells capable of responding directly to HCG were identified by isotopic in-situ hybridization for messenger RNA encoding LH/HCG receptors. Macrophages were localized primarily to the vascular connective tissue and theca-lutein areas of the corpus luteum, although some were found in the granulosa-lutein cell layer. Macrophage numbers increased throughout the luteal phase to a maximum in the late-luteal phase (P < 0.05). Luteal 'rescue' with HCG was associated with a marked reduction in the numbers of tissue macrophages when compared with those of the late-luteal phase (P < 0.001). One of the effects of HCG during maternal recognition of pregnancy is to prevent the normal influx of macrophages into the corpus luteum. As LH/HCG receptors localized to the steroidogenic cells, this implies a fundamental role for steroidogenic cell products in the control of macrophage influx into the human corpus luteum.Human Reproduction 09/1998; 13(9):2435-42. DOI:10.1093/humrep/13.9.2435 · 4.59 Impact Factor
- Biology of Reproduction 04/1995; 52(4):776-792. DOI:10.1095/biolreprod52.4.776 · 3.45 Impact Factor
- Biology of Reproduction 08/1998; 59(2):417-425. DOI:10.1095/biolreprod59.2.417 · 3.45 Impact Factor