Maternal anti-fetal cytotoxic antibody responses of equids during pregnancy.
The maternal immunological response to the developing equine fetus was investigated in 69 pregnancies of various genotypes. In normal intraspecies horse pregnancy (N = 16), 94% of mares produced strong cytotoxic antibody responses to paternal histocompatibility antigens which were first detectable between 44 and 70 days after ovulation. In all other types of pregnancy examined (intraspecies donkey, N = 19; interspecies mule, N = 6; interspecies hinny, N = 2; extraspecies horse-in-donkey, N = 3; and extraspecies donkey-in-horse, N = 21), antibody production was observed less frequently, and sometimes with a more irregular onset. However, the dominant pattern of response was similar to that observed in intraspecies horse pregnancy. Although the development of cytotoxic antibody correlated well with the formation of the equine endometrial cups, histological and serological evidence demonstrated that the accumulation of lymphocytes which occurs around the endometrial cups in intra- and interspecies pregnancies, and in the endometrial stroma in contact with trophoblast in extraspecies donkey-in-horse pregnancies which lack endometrial cups, can occur in the absence of a detectable cytotoxic antibody response. The cytotoxic antibody produced by mares carrying extraspecies donkey conceptuses appeared to be directed primarily against donkey alloantigens, and not species-specific antigens, emphasizing the importance of maternal recognition of paternally derived fetal histocompatibility antigens during equine pregnancy.
D000818:Animals; D000917:Antibody Formation; D003433:Crosses, Genetic; D003602:Cytotoxicity, Immunologic; D005260:Female; D006736:Horses / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology; D010527:Perissodactyla / Q000276:immunology; D011247:Pregnancy; D011270:Pregnancy, Animal; D013045:Species Specificity; D014327:Trophoblasts / Q000276:immunology