Effects of placental extracts on the immune response to histocompatibility antigens: class deviation of alloantibody response and allograft enhancement.

Placental extracts obtained from CBA (H-2k) mice during syngeneic (CBA female X 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 favoured antibody-mediated mast cell degranulation (IgG1) and Sa 1 allograft enhancement. The presence and role of IgG1 antibodies in both tumor enhancement and gestation has been described. It is concluded that 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.