Next, we analyzed the frequencies of CD4+CD25+ Tregs and the capacity of Tregs to suppress CD4+ CD25− T cell proliferation in dry eye and healthy graft recipients, and found that both frequencies (Fig. 1C) and suppressive function (Fig. 1D) of Tregs were significantly suppressed in hosts with dry eye compared to healthy controls. Here, CD4 is linked to Keratoconjunctivitis sicca.