Failure to suppress theta antigenic expression in progeny derived from pre-immunized maternal recipients.

One possible theory concerning the success of the fetus as an allograft has been attributed to maternal modification of foreign fetal antigenic expression. In this respect progeny derived from pre-immunized maternal mouse recipients, have been examined for any modification (reduction) of corresponding theta antigen determinants. Two major groups of mice were examined. The first group of embryo transplantation derived AKR homozygotes born from pre-immunized CBA recipients whilst producing the corresponding anti-thetaAKR antibody activity. The second group of naturally derived reciprocal (CBA x AKR)F1 heterozygotes were also born from pre-immunized maternal recipients. In neither group was theta expression found to be modified and the significance of this finding is discussed in respect of other situations where fetal antigenic expression is known to be altered by maternal influence.