LOCALIZATION OF STRESS PROTEIN-70 IN OVINE CORPORA-LUTEA DURING PROSTAGLANDIN-INDUCED LUTEOLYSIS

Accumulation of heat shock (stress) protein-70 (HSP-70) was assessed i n corpora lutea of sheep obtained after in vivo administration of a lu teolytic dose of prostaglandin (PG) F2alpha. A quantitative immunofluo rescence technique was used to localize inducible HSP-70 production to specific cell-types. The number and intensity of immunostained large luteal cells increased within 2 h of injection of PGF2alpha. A drop in luteal progesterone concentrations (functional regression) was not ma nifested until 4 h post-treatment. A dramatic increase in intensely-st ained mononuclear leukocytes was observed in luteal tissues at 16 h, w hen glandular weights had begun to diminish (structural regression). S tress proteins could mediate intracellular protein processing and cell -surface autoimmune mechanisms underlying luteal regression.