Evaluation of the pregnancy immunotrophism hypothesis by assessment of the reproductive performance of young adult mice of genotype scid/scid.bg/bg

The hypothesis that enhancement of pregnancy success results from immune recognition of the conceptus was evaluated by studying reproductive performance in a new line of mice deficient in NK cells and lacking B cells and T cells. Doubly mutant mice of genotype scid/scid.bg/bg are both viable and fertile. The numbers of offspring born to pairs of this genotype were not different from numbers born to heterozygous pairs. Differences in prenatal loss could not be found between genotypes by counts of either fetal resorption sites or corpora lutea. The timing of developmental stages and the differentiation of trophoblast, placenta, decidua and metrial gland in scid/scid.bg/bg mice appeared normal. These results suggest either that lymphokine influences on trophoblast cells in vivo do not contribute, in a major way, to pregnancy success or that the important cytokines are derived from uterine cell populations that are not classical, mature B cells, T cells or NK cells.