Endothelial chimerism after ABO-incompatible kidney transplantation.

BACKGROUND

Endothelial chimerism in transplanted organs can be defined as the presence of recipient-derived endothelial cells in the donor organ. The mechanism of endothelial chimerism is not well understood and remains controversial. The purpose of this study was twofold. First, we investigated the presence of chimerism in renal allografts of ABO-incompatible kidney transplantation recipients. Second, we analyzed the association between chimerism and the clinical course and histopathological changes.

METHODS

We investigated the presence of chimerism in renal allografts of ABO-incompatible kidney transplantation recipients by immunohistochemical detection of blood type A and B antigens and assessed the association between chimerism, the clinical course, and histopathological changes. Among a total of 56 patients (29 blood group A incompatible and 27 blood group B incompatible), 49 cases (28 blood group A incompatible and 21 blood group B incompatible) were enrolled in this study. Blood group antigens were stained using immunohistochemistry.

RESULTS

Twelve of the 49 patients (12/49, 24.5%) exhibited endothelium chimerism in a biopsy sample. Among the 12 patients with endothelium chimerism, 7 patients (7/12, 59%) had acute and chronic active antibody-mediated rejection and 2 patients (2/12, 17%) had severe calcineurin inhibitor toxicity. The graft survival rate in the chimerism group was significantly lower than that in the no-chimerism group ([chimerism vs. no-chimerism] 3 years, 83.3% vs. 97.1%; 5 years, 74.1% vs. 97.1%; 8 years, 46.3% vs. 97.1%; P<0.0001).

CONCLUSIONS

Endothelial chimerism seems to be a hallmark of vigorous immune or nonimmune responses, such as antibody-mediated rejection or calcineurin inhibitor toxicity, and not of the induction of tolerance.