Submission Number: ANT-4-417-190

Abstract Number: 1

IMMUNE CELLS AND PLACENTATION.

DF Antczak, Jessica M Baker and A Paige Adams

The James A. Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York ¹

Abstract:
The functions of leukocytes in the uterus during pregnancy remain a mystery. The uterus is part of the mucosal immune system, along with the respiratory and gastrointestinal tracts, and as such contains many of the components of other parts of this system. However, the differences between species in the structure and function of the reproductive tract have made it difficult to determine the interplay between the uterine immune system and the developing conceptus. One source of difficulty is that the principal populations of uterine leukocytes differ between species. In rodents and primates, which have hemochorial placentae, the majority of the leukocytes in the area of the decidua are the so-called uterine Natural Killer (NK) cells. In domestic farm animals, including sheep, cattle, pigs, and horses, which have less invasive syndesmochorial or epitheliochorial placentae, the majority of the leukocytes appear to be conventional CD4+ or CD8+ T lymphocytes.

Have these differences in uterine leukocyte populations arisen because of differences in placentation, or for reasons to do with immune defense against infection? The insult of mating presents a formidable immunological challenge to the sterility of the uterus in any species, but this is especially so in species with intrauterine deposition of semen, such as the horse. New methods for studying leukocyte function in situ, and ex vivo have opened new avenues for understanding how the uterine immune system interacts with the developing placenta. Recently, we have developed a method for transplanting equine invasive trophoblast tissue into ectopic sites outside of the uterus. This method permits investigation of trophoblast - immune system interactions in which the hormonal status of pregnancy does not interfere with assessment. Results to date indicate that the trophoblast itself plays a major role in evading immune responses, and that immune responses similar to those observed in the uterus can occur in other sites.

Keywords: uterus, leukocytes

This abstract is being presented at: 10:30 AM in session:
Minisymposium VIII: IMMUNE PRIVILEGE IN THE PREGNANT UTERUS