SUPPRESSION OF SHEEP AND GOAT LYMPHOCYTE-PROLIFERATION BY SHEEP, GOAT, AND SHEEP X GOAT HYBRID TROPHOBLAST TISSUE-CULTURES

Immunosuppressive activity of conditioned medium from cultured ovine, caprine, and hybrid trophoblast tissue was examined. Conceptuses were obtained from naturally mated donor ewes and does at d 20 of gestation and trophoblast tissue was cultured for 24 h in medium supplemented with 15% calf serum and 1% antibiotic/antimycotic. Conditioned medium was added to pokeweed mitogen-stimulated sheep and goat lymphocyte cultures. Quantification of [H-3]thymidine uptake by cells was used to measure lymphocyte proliferation. Ovine, caprine, and hybrid conditioned medium effectively suppressed sheep and goat lymphocyte proliferation (P < .01). There were no differences (P > .05) between the immunosuppressive activity of the three tissue types on either sheep or goat lymphocytes. For all treatment groups, sheep lymphocytes were suppressed more than goat lymphocytes (P < .05). These results indicate that, at d 20 of gestation, sheep x goat hybrid trophoblast tissue is capable of suppressing pokeweed mitogen-stimulated lymphocyte proliferation.