Immunogenetic studies of spontaneous abortion in mice. II. Antiabortive effects are independent of systemic regulatory mechanisms.

CBA/J females (H-2k) mated with DBA2/J males (H-2d) exhibit a high rate of fetal resorption. Fetal survival has been improved by pretreatment of CBA/J females with spleen cells from BALB/c J (H-2d) (but not from CBA/J or DBA/2/J) males. Similarly, three out of nine recombinant inbred strains (recombining BALB/c and DBA2 genomes at the homozygous state) possess antiabortive effects like the BALB/c parent. Previous studies showed that BALB/c pretreatment triggers the appearance of suppressor cells in the spleen and of IgG1 anti-H-2d antibodies in the serum of CBA/J females. Studies of these two immunological parameters after CBA/J preimmunization by the different recombinant strains suggest that local intrauterine immunoregulation is the determinant of success or failure of allopregnancy.