Abstract
Purpose: :
We have previously demonstrated that both IFN-γ+ and IL-17+ IRBP-specific T cells play a major role in the pathogenesis of experimental autoimmune uveitis (EAU). Recently, we have found that a major portion of the IL-17 producing T cells isolated from B6 mice immunized with an uveitogenic IRBP peptide (IRBP1-20) expressed γΔ TCR. We therefore determined the role of γΔ T cells in the pathogenesis of EAU.
Methods: :
γΔ T cells were positively sorted out using magnetic sorter from the IRBP1-20-primed splenic T cells 5 days after the in vitro stimulation with immunizing antigen. To depletion γΔ T cells in vivo, naive mice were treated either with antibody specific for γΔ TCR (GL3). For intracellularly staining of IL-17+ T cells, T cells subjected for analysis were stimulated in vitro with 50 ng/ml of PMA, 1 µg/ml of ionomycin, and 1µg/ml of brefeldin A for 4 h, then were washed, fixed, permeabilized overnight with Cytofix/Cytoperm buffer, and stained with antibodies against IFN-γ and IL-17 and analyzed on a FACScalibur flow cytometer.
Results: :
Numbers of peripherally circulating γΔ T cells increased rapidly in B6 mice immunized with the uveitogenic peptide IRBP1-20, which expanded vigorously during subsequent in vitro culture. Highly purified αβ and γΔ T cells produced low levels of IL-17 after exposure to the immunizing antigen in vitro; however, responder T cells mixed with αβ and γΔ T cells at varying ratios produced greatly increased amount of IL-17. Depletion of γΔ T cells of the EAU-prone B10RIII mice drastically decreased the disease severity as well as the IL-17 production of the in vivo primed IRBP-specific T cells.
Conclusions: :
Our results show that γΔ T cells are important immune components in the generation and activation of IL-17-producing autoreactive T cells as well as in the pathogenesis of EAU.
Keywords: immunomodulation/immunoregulation • uveitis-clinical/animal model • inflammation