Two-way calf to dam major histocompatibility class I compatibility increases risk for retained placenta in cattle.

Abstract

PROBLEM: In cattle, retained placenta (RP) is suggested to arise from failure of immune-mediated rejection of the fetal membranes by the maternal immune system and is associated with major histocompatibility (MHC) class I compatibility between calf and dam. METHOD OF STUDY: To study the association between RP and different MHC class I compatibilities between calf-dam-granddam combinations, massively parallel pyrosequencing was used to determine the MHC class I haplotypes of cows with and without RP. RESULTS: Two-way calf to dam MHC class I compatibility gave a high risk for RP. There was a tendency for a higher risk for RP with calf to dam MHC class I compatibility. CONCLUSIONS: We concluded that in two-way compatible pregnancies, the maternal immune system fails to reject the fetal membranes, and the fetal immune system does not mount an immune response against maternal MHC class I antigens that could influence the immune-mediated rejection of the fetal membranes by the maternal immune system. The lack of immune-mediated rejection of the fetal membranes by the maternal immune system increases the risk of occurrence of RP.