γδ T cells regulate the expression of cytokines but not the manifestation of fungal keratitis.

As an important immunoregulatory cell type, the role of γδ T cells in fungal keratitis (FK) is unclear. We observed the distribution of γδ T cells in infected corneas in vivo by two-photon microscopy. The γδ T cells were depleted by neutralizing antibodies. The cytokine expression profile was obtained by protein arrays to determine the cytokines regulated by γδ T cells. ICAM-1, MIP-2 and IL-17A were evaluated by ELISA assays to confirm the role of γδ T cells in FK. We counted the number of neutrophils, evaluated the volume of fungal hyphae and analyzed the manifestation of the disease. The γδ T cells increased significantly at 36 h and 72 h post fungal infection (P < 0.05) and migrated from the limbus to the infection site. The neutralizing antibodies completely depleted the γδ T cells in 24 h. The depletion of γδ T cells led to up regulation of 25 cytokines and down regulation of 3 cytokines. ICAM-1, MIP-2 and IL-17A changed significantly because of the depletion of γδ T cells (P < 0.05). However, the number of neutrophils, volume of fungal hyphae and manifestation of the disease was not affected by the depletion of γδ T cells. Our results demonstrated that γδ T cells have a role in FK via regulation of some cytokines but did not affect the manifestation of this disease, suggesting that γδ T cells are not the key regulator cells in this disease.