Male microchimerism in peripheral blood of women awaiting kidney transplantation correlates positively with HLA allo-immunization (102.19)

Abstract Microchimerism is the persistence of a small population of donor or fœtal cells, in graft recipients or in mothers. It appears after transfusion, pregnancy, transplantation and has been implicated in graft rejection, tolerance and auto-immunity. Anti-HLA Ab can appear under identical circumstances. Why and how such Ab persist for decades is only partially understood. We questioned if male microchimerism in the peripheral blood of women could be one of the mechanisms allowing the maintenance of anti-HLA Ab production. We evaluated 46 women, waiting for a first kidney graft, for the presence or absence of anti-HLA Ab using an ELISA. A Panel Reactive Ab was determined using Luminex® technology. Y chromosomal DNA was identified by nested PCR using specific primers of the SRY region. All patients were pregnant and/or transfused. In the Ab+ group (n=24), all women were sensitized and in the Ab− group (n=22), all women were unsensitized. Thirty-nine percent of all women (18/46) carried a male microchimerism: 54% in the Ab+ group (13/24) vs. 22% in the Ab− group (5/22) with pχ2= 0.029. We found a significant frequency of male microchimerism in the peripheral blood of women with kidney disease, which positively correlated with the presence of anti-HLA Ab.