Suppression of lymphocyte reactivity to phytohemagglutinin & mixed lymphocyte culture by human placental syncytiotrophoblast
Paul, S.; Mehrotra, N.N.; Jailkhani, B.L.
Indian Journal of Experimental Biology 20(3): 204-208
1982
ISSN/ISBN: 0019-5189 PMID: 6214506 Document Number: 195336
Purified human placental syncytiotrophoblast (ST) was maintained in viable and metabolically active state in tissue culture. Addition of cultured ST or its cell free culture supernatants to cultures of unrelated lymphocytes suppressed the proliferative responses of the latter to phytohemagglutinin [PHA] and mixed lymphocyte culture. This suppression of lymphocyte reactivity was dependent upon the dose of the ST (or the ST culture supernatant) and was not due to lymphotoxicity. Variation of the dose of PHA between 10-160 .mu.g/ml failed to relieve the inhibitory effect of the ST culture supernatant upon the response of the lymphocytes to the mitogen. Lymphocytes preincubated with the ST culture supernatant for 2 h, washed free of the latter, and then exposed to PHA, still exhibited a depressed proliferative response. Placental ST and its secretory products apparently suppress the mitogen reactivity of lymphocytes, and allogenic recognition in mixed lymphocyte culture. This lymphocyte-suppressor function of ST may be important in the non-rejection of the immunologically alien fetus by the mother in vitro.