EFFECT OF INTERLEUKIN-3 ON OVINE TROPHOBLAST INTERFERON DURING EARLY CONCEPTUS DEVELOPMENT

The effect of interleukin-3 (IL-3) on conceptus production of ovine in terferon tau (olFN tau) was examined using two dimensional sodium dode cyl sulfate-polyacrylamide gel electrophoresis (2D SDS-PAGE), western blot, northern/slot blot, in situ hybridization and immunohistochemica l methodologies. Ovine conceptuses (day 17, n = 14) were cultured in v itro for 24 h in Eagle's Minimum Essential Medium (MEM) containing var ious doses of human recombinant interleukin-3 (hIL-3). At 75 and 150 c olony forming units (units)/ml hIL-3, amounts of olFN tau released int o the culture media increased 3-8-fold over controls while at 300 unit s/ml (60 pM), hIL-3 did not enhance olFN tau production. These variati ons in production of olFN tau paralleled amounts of olFN tau mRNA dete cted by northern and slot blot analyses. Ovine IL-3 mRNA was primarily localized at luminal and glandular epithelia with minor staining at s tromal regions of uterine endometria collected from day 17 pregnant ew es but its polypeptide was localized in the luminal epithelial region. However, such signals were not detected in day 17 conceptuses. Ovine IL-3 mRNA and its polypeptide were also localized at the same regions of the endometrium obtained from cyclic ewes on days 8 and 12. The eff ect of hIL-3 on the enhancement of olFN tau production in vitro could be mimicked by the addition of phorbol 12-myristate 13-acetate (PMA). The present observations demonstrate that the hemopoietic cytokine, IL -3, stimulates conceptus production of olFN tau in vitro and that ovin e IL-3 and its mRNA are localized in the maternal endometrium. These r esults suggest that a cytokine, IL-3, produced by the maternal endomet rium, is involved in conceptus production of olFN tau which may result from the activation of a second messenger system, protein kinase C.