Expression of a p55 interleukin-2 receptor-like molecule on corneal epithelial cells

We observed a molecule on the surface of mouse corneal epithelial cells that is similar or identical to the p55 subunit of the high affinity interleukin-2 receptor (p55 IL-2R). The presence of this molecule in normal corneas was demonstrated by immunoperoxidase staining with a monoclonal antibody (mAb) specific for p55 IL-2R (7D4). Staining was observed only in the corneal epithelium. The staining intensity was greatest in the central cornea, becoming weaker toward the corneal scleral limbus, and was very weak or absent in the conjunctival epithelium. Other ocular tissues were not stained. Epithelial cells grown in tissue culture from corneal explants retained expression of the molecule recognized by 7D4 as demonstrated by immunoperoxidase staining. Western Blot analysis of an extract of corneal epithelium demonstrated the presence of a 55 kD protein that reacted with 7D4. Our findings suggest that a molecule similar both antigenically and in molecular size to the p55 IL-2R subunit is constitutively produced by corneal epithelial cells.