Effects of the chromatographic fractions of the pig placental trophoblast on graft-versus-host reaction

The trophoblast has a significant role in regulation of immune reactions at the materno-fetal interface by producing biologically active substances. I n our previous studies five fractions with immunomodulatory activities were isolated by gel chromatography from trophoblast of pig placentas. To confi rm the immunomodulatory effect of these trophoblast fractions on allogeneic in vivo systems and to obtain more evidence for the relevance of their act ivity on the maternofetal interface, their effect was studied on graft-vers us-host reaction (GVI-JR). To assess the GVHR, the primary and secondary po pliteal lymph nodes assay was used in mice. In the primary GVHR, 100 mu g p rotein of Fraction 2-5, mixed with 5 x 10(6) allogeneic spleen cells (C57BL /(6)), were injected into one of the foot pads of recipient (BALB/c) mice. The secondary GVHR was induced in Fl (BALB/c x C57BL/(6)) mice by injection of spleen cells of BALB/c mice intraperitoneally preimmunized with allogen eic cells. The GVHR was measured by the weight of lymph nodes and by the ly mphocyte proliferation. Flow cytometric analyses of the cells in the nodes with GVHR and under the influence of Fraction 4 or 5 were performed using m onoclonal antibodies. In the primary GVHR, Fraction 4 or 5, injected simult aneously with allogeneic spleen cells, significantly suppressed the lymph n odes reactivity. Fractions 4 and 5 inhibited the ability of the spleen cell s of mice intraperitoneally preimmunized with allogeneic cells to induce se condary GVHR in Fl mice. The Fraction 2 and 3 had no effect on GVHR. The re sults revealed that a group of proteins with Mr 37-7 kDa, isolated from tro phoblast of pig placenta, strongly suppressed popliteal lymph node reactivi ty in the primary and secondary GVHR. The data provide convincing evidence for these fractions in vivo activity, for their effect across the species b arrier and suggest the relevance of the same reactions on the materno-fetal interface. (C) 2000 by Elsevier Science Inc.