Are You Motherʼs Darling? the NIMA Effect

Abstract

Background: Exposure of the immune system of a child to noninherited maternal antigens (NIMA) during pregnancy might lead to long lasting down regulation of the alloresponse against these NIMA: the NIMA effect. Therefore graft survival of a kidney from a mother would be superior to that from a father. We tested this hypothesis in our transplant population. Methods: Between 1981 and September 2011 we performed 1138 living donor kidney transplantations. 250 parents donated a kidney to their child. In 101 transplantations, the donor was the father of the recipient and in 149 the mother donated. Cox proportional hazards analysis was performed studying the effect of recipient gender and age, current PRA, transplantation year, HLA mismatches, donor age, rejection, and donor gender (father/mother) on the risk of graft failure censored for death. Results: In the period studied there were 60 graft failures (35 in recipients from mother, 25 in recipients from fathers). Acute rejection episodes occurred in 46 recipients of a kidney from mother and 38 recipients of a kidney from father (ns). Cox proportional hazards analysis showed that only donor age and rejection significantly influenced the risk of graft failure censored for death. Conclusion: In recipients of kidneys from a parent, donor gender did not influence the risk of graft failure or the incidence of acute rejection. The NIMA effect is not detectable in our population of immunosuppressed recipients of a kidney donated by mothers.