Effects of Placental Extracts on the Immune Response to Histocompatibility Antigens: Class Deviation of Alloantibody Response and Allograft Enhancement

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Abstract
Placental extracts obtained from CBA (H-2k) mice during syngeneic (CBA .female. .times. CBA .male.) pregnancy were evaluated for their capacity to deviate the immune reaction of CBA mice toward A/J(H-2a) immunizing spleen cells, as tested by alloantibody subclass formation and Sa 1 allograft accelerated rejection or enhancement. The immunomodulatory activity appeared to be located in the soluble and in the insoluble extracts of placenta. The sodium deoxycholate (SDO) solubilized proteinic material, fractionated on concanavalin A [Con A] and injected to CBA mice simultaneously with A/J spleen cells caused a suppression of the hemagglutinating titer and C-mediated cytotoxicity (IgG2). However, it also favored antibody-mediated mast cell degranulation (IgG1) and Sa 1 allograft enhancement. The presence and role of IgG1 antibodies in tumor enhancement and gestation has been described. Placenta contains Con A-binding glycoproteins which are located in the membranes and released in soluble form. They exert their immunomodulatory effect in a way which might help the successful outcome of pregnancy as it helps to enhance the development of allografted sarcoma.