Expression of ABO Blood Group, Hematopoietic, and Other Cell-Specific Antigens by Cells in the Human Cornea

Abstract

Because of controversy surrounding the expression of ABO blood group (ABH) antigens (which may act as transplantation antigens) in human cornea, we examined the expression of these antigens in a panel of normal corneas using a highly sensitive avidin-biotin complex immunoperoxidase technique. ABH antigens were expressed by the corneal epithelium from all donors in a pattern consistent with their red blood cell phenotype, but were absent from stroma and endothelium. We also examined the same corneas for cells expressing hematopoietic cell markers in an effort to determine which marrow-derived cells may be contributing (as "passenger leukocytes") to the immunogenicity of corneal allografts. Scattered cells positive for a pan-hematopoietic cell marker (T29/33) were present throughout all corneas, but no consistent expression was noted of markers for B lymphocytes, monocytes, or NK cells. Adult corneas showed occasional T lymphocytes, predominantly in the limbus. Finally, we looked for the expression by these corneas of a variety of cell-specific and structural antigens, to identify possible relationships between corneal cells and analogous cell populations. We found that corneal endothelial cells expressed one vascular endothelial antigen, (HuEE12), but not another (Factor VIII related antigen), suggesting a possible relationship between corneal endothelium and its immunologically important vascular counterpart. Various structural antigens were found in predicted associations with corneal endothelial, stromal, and epithelial cells. These findings cast new light on the antigens involved in corneal allograft reactions and the immunologic nature of some constituent corneal cells.