Studies on the immunological interaction between mother and foetus

Abstract

Studies have been made of the immunological interactions that occur between inbred female mice and their hybrid foetuses.The effectsof maternal sensitization to paternal antigens have been examined. Contrary to earlier reports, it appears that allogeneic immunization has no effect on placental size at the eighteenth day of pregnancy but causes a small consistent depression of foetal weight. Reduction of litter size, and implantation number, and an increase in foetal death are sometimes but not always apparent. The immunization of the mother to Peromyscus antigens also reduces litter size and increases the number of foetal deaths. This suggests that non -specific factors of immunization may be responsible. Non -specific immunization also depresses foetal weight but the effect is smaller than that caused by specific immunity. It is suggested that further experiments involving immunization should take into account the influence of non -specific factors.Although the mechanisms protecting the foetus from maternal sensitization are efficient in the later stages of pregnancy, the early stages appear to be more susceptible to interference.Injections of the enzyme hyaluronidase, which increases placental permeability, have no effect on hybrid foetal and placental weight at the eighteenth day, but tend_ to increase the numbers of early foetal deaths. The effect is restricted to mother s sensitized to paternal antigens.The removal of the spleen from allogeneically immunized females also fails to affect foetal and placental weights, and increases early foetal mortality. On the basis of these, and other observations, it is proposed that the presence of "enhancing" antibodies may play a role in protecting the early foetus.A study was made of the effects of active maternal sensitization, and passively transferred antiserum, on the development of the uterine decidual cell response at the seventh day of pregnancy. The results show that active immunization to paternal antigens significantly reduces the size of the decidual response. The effectiveness of passively transferred antisera demonstrateSthat humoral, rather than cellular, components are responsible. The use of different methods of active immunization gives evidence that the diminished response is dependent on a particular kind of antibody. The strength of antibody in individual maternal serum determines the degree of decidual inhibition.Inbred and hybrid eggs were cultured in the presence and absence of antiserum. The results show that whereas transplantation antigens can be demonstrated on the surface of oviducal embryos, hybrid embryos appear to be deficient in the expression of paternal antigens.The problem of the foetus as a homograft is discussed in the light of present knowledge.