The Expression of MHC Class I-Related Chain A Molecule in Human Corneal Tissue

Abstract

Purpose: : Although corneal allografts enjoy a remarkable degree of immune privilege, immune rejection remains the leading cause of graft failure. Yet large gaps remain in our knowledge regarding the cellular and molecular mechanisms of corneal allograft rejection. The human MICA (MHC class I-related chain A) are believed to be "cell stress sensors" and are expressed on epithelial cells in response to stress. Due to their polymorphism, incompatible donor MIC antigens can stimulate activating NK cells, CD8⁺ T cells, and gamma/delta T cells in transplant recipients. This study was designed to investigate the MICA expression in normal human cornea and rejected corneal graft.

Methods: : We used RT-PCR to analyze the mRNA expression of MICA in normal human cornea. By using goat polyclonal antibodies in an indirect immunofluorescence assay, MICA expression in human cornea, especially in rejected corneal graft, was detected. Information about clinical course of regraft patients was also summarized.

Results: : MICA gene was transcripted in the normal cornea. Meanwhile, Immunochemistry showed MICA expressed in the normal cornea and the rejected corneal graft, even regraft patients were administered aggressive immunosupression treatment preoperatively.

Conclusions: : This is the first study demonstrating the MICA expression in human corneal tissue. Though the mechanism of MICA expression needs to be elucidated, it may contribute to the alloimmune response in corneal transplantation.

Keywords: cornea: basic science • transplantation • cornea: clinical science