CD4+CD25+Tregs express an increased LAG-3 and CTLA-4 in anterior chamber-associated immune deviation

Regulatory CD4(+)CD25(+) T cells have been proven to be essential for maintenance of peripheral tolerance and autoimmune diseases. ACAID is a model of immune privilege in the eye. Relatively little is known about the role and phenotype of these regulatory CD4(+)CD25(+) T cells in ACAID.

Injection of OVA into the anterior chamber of BALB/C mice was performed to induce ACAID. The frequencies of splenic CD4(+)CD25(+) Tregs and the expression of CTLA-4 and LAG-3 on these cells were determined by flow cytometry. Magnetic cell sorting was used to isolate CD4(+)CD25(+) and CD4(+)CD25(-)T cells. The function of CD4(+)CD25(+) T cells was detected by in vitro immunosuppression assays and in vivo adoptive transfer.

ACAID was successfully induced following an i.c. injection of OVA. Frequencies of CD4(+)CD25(+) and Tregs were significantly increased in ACAID mice as compared to those in controls. The CD4(+)CD25(+) T cells stimulated with OVA in ACAID mice showed a stronger suppressive ability in vitro than those seen in non-ACAID mice. CD4(+)CD25(+) T cells from ACAID mice, but not from non-ACAID mice, were able to suppress DTH responses in an antigen-specific manner following adoptive transfer. The frequencies of CTLA-4 or LAG-3 on Tregs in ACAID mice were higher as compared with those in naive mice.

Splenic CD4(+)CD25(+)Foxp3(+)T cells expressing CTLA4 and LAG3 play an important role in the induction of ACAID.