Increased expression of Foxp3 in splenic CD8(+) T cells from mice with anterior chamber-associated immune deviation

PURPOSE: To examine the expression of Foxp3 on CD8(+) T cells in the spleen during anterior chamber-associated immune deviation (ACAID). METHODS: Ovalbumin (OVA) was injected into the anterior chamber (AC) of C57BL/6 mice, and the delayed-type hypersensitivity (DTH) response was measured to evaluate the development of ACAID. The suppressive effect of CD8(+) T cells in ACAID mice was determined by a local adoptive transfer (LAT) assay. Flow cytometry was used to assay the frequency of CD8(+)Foxp3(+) T cells from normal mice, ACAID mice, and control mice receiving an AC injection of PBS (PBS-AC-injected mice). These frequencies were also tested after polyclonal or specific antigen stimulation. The mRNA level of Foxp3 in CD8(+) splenocytes from different groups with or without stimulation were determined by reverse transcription-polymerase chain reaction. RESULTS: OVA injection into the AC induced ACAID, and CD8(+) T cells from ACAID mice inhibited the ear-swelling response by OVA-primed responder cells in LAT assay. Flow cytometry analysis showed that the frequency of CD8(+)Foxp3(+) cells in splenocytes was upregulated in ACAID mice following polyclonal or specific antigen stimulation. Foxp3 mRNA was only detected in CD8(+) T cells from ACAID mice after polyclonal stimulation. CONCLUSIONS: An upregulated Foxp3 expression in CD8(+) T cells is associated with the development of ACAID, suggesting an involvement of CD8(+)Foxp3(+) T cells in this model of immune tolerance.