Identification of MICA as a new polymorphic alloantigen recognized by antibodies in sera of organ transplant recipients

ZWIRNER, NORBERTO WALTER; MARCOS, CINTIA YANINA; MIRBAHA, FARIBA; ZOU, YIZHOU; STASTNY, PETER

HUMAN IMMUNOLOGY

Elsevier

Lugar: New York; Año: 2000 vol. 61 p. 917 - 924

0198-8859

MICA is an HLA related, polymorphic gene the product of which may be recognized by a subpopulation of intestinal gd T cells and may play a role in the activation of a subpopulation of NK cells. Using anti-MICA specific rabbit sera we previously demonstrated that freshly isolated monocytes, keratinocytes, fibroblasts and endothelial cells express MICA. In order to analyze whether MICA may be a target for specific antibodies in sera of transplanted patients, we produced three recombinant MICA proteins consisting of the a1, a2, and a3 domains, and used them in an ELISA assay. We found that several patients had specific Abs against MICA. Most of them were detected in serum samples collected at different times after organ rejection. Although this finding raises the question of how these patients became immunized, the fact that the polymorphic, HLA-like MICA molecule, expressed at the cell surface of endothelial cells, is recognized by specific Abs in sera of transplanted patients, suggests the MICA may be a target molecule in allograft rejection.