γδ T cells are necessary for platelet and neutrophil accumulation in limbal vessels and efficient epithelial repair after corneal abrasion

Corneal epithelial abrasion in C57BL/6 mice induces an inflammatory response with peak accumulation of neutrophils in the corneal stroma within 12 hours. Platelets localize in the limbal vessels throughout the same time course as neutrophils and contribute to wound healing because antibody-dependent depletion of platelets retards epithelial division and wound closure. In the present study, T cells in the limbal epithelium were found to predominantly express the gamma delta T-cell receptor (TCR). Corneal abrasion in wildtype, CD11a(-/-), and P-sel(-/-) mice increased the numbers of gamma delta T cells in the limbal and peripheral corneal epithelium and in the corneal stroma adjacent to the limbal blood vessels. Intercellular adhesion molecule (ICAM)-1(-/-) mice exhibited a reduction in gamma delta T-cell accumulation. TCR delta(-/-) mice exhibited reduced inflammation and delayed epithelial wound healing as evidenced by delayed wound closure, reduced epithelial cell division, reduced neutrophil infiltration, and reduced epithelial cell density at 96 hours after wounding. TCR delta(-/-) mice also exhibited >60% reduction in platelet localization in the limbus despite similar platelet counts and platelet function assessed with an in vivo thrombosis model. These results are consistent with the conclusion that gamma delta T cells are necessary for efficient inflammation, platelet localization in the limbus, and epithelial wound healing after corneal abrasion.