Expression of blood group antigens A and/or B in diseased corneas

Only epithelial cells are thought to express blood group antigens (bga) A and/or B in normal corneas, and ABO blood group (bg) matching seems to reduce immune rejection in high risk transplantations. This study attempts for the first time to investigate to what extent the bga A and/or B are expressed in diseased corneas.

Thirty-nine diseased corneal buttons of 39 patients were examined. Immunohistochemical staining of paraffin-embedded sections was performed with monoclonal mouse anti human blood groups A and B antibodies using the Streptavidin-Biotin-peroxidase complex technique (LSAB Kit, Dako).

The expression of blood group antigens A and/or B on the cornea was found to correlate directly with the blood group of the patients in all cases. The corneal epithelium of all 18 patients with blood groups A and/or B could be stained with antibodies to bga A and/or B. However, neither bga A nor bga B could be detected in any corneal cells of patients with the blood group O (21 patients). In addition to the epithelium, the stromal keratinocytes as well as the endothelium contained immunohistochemically detectable bga A and/or B in cases of keratitis or keratoconus, but not in stromal and/or endothelial cells of corneas with pseudophakic bullous keratopathy and Fuchs' dystrophy (all patients with the bgs A and/or B).

These findings show that an up-regulation of bga A and/or B in corneal stromal and endothelial cells is possible in diseased corneas. This phenomenon might play an important role in graft rejection after corneal transplantation.