CD4 and Keratoconjunctivitis sicca: [13], [14] In the iris, CD8+T cells once activated in the presence of parenchymal cells, expressed and secreted enhanced amounts of TGF-β2. [15] In certain conjunctival inflammatory conditions, including graft-versus-host disease, Sjögren’s syndrome and human and experimental murine keratoconjunctivitis, a significant decrease in CD8+T cells with concomitant increase in CD4/CD8 ratio in the conjunctiva has been observed. [5], [11], [16] We have found that conjunctival CD8+T cells work as regulatory cells during experimental dry eye (manuscript under review).