Treg cells in MUC1.Tg mice contained MUC1-specific populations.

<p>Antigen specificity of Treg cell suppression was investigated <i>in vitro</i>. (A) MUC1-specific T cell hybridoma VF5 cells (1×10⁵ cells) were co-cultured with BM-DCs (2×10⁴ cells) pulsed with MUC1 peptide and CD4⁺ T cells as indicated. (B) VF5 cells (1×10⁵ cells) were cultured alone or co-cultured with BM-DCs (2×10⁴ cells) pulsed with or without MUC1 peptide (+/−MUC1p). (C) OVA-primed CD4⁺ T cells (1×10⁵ cells) were co-cultured with BM-DCs (2×10⁴ cells) pulsed with OVA protein and CD4⁺ T cells as indicated. (D) OVA-primed CD4⁺ T cells (1×10⁵ cells) were cultured alone or co-cultured with BM-DCs (2×10⁴ cells) pulsed with or without OVA (+/−OVA). (E) OVA-specific OT-II T cells (4.5×10⁴ cells) were co-cultured with BM-DCs (4.5×10³ cells) pulsed with OVA peptide and/or MUC1 peptide and CD4⁺ T cells obtained from MUC1.Tg mice as indicated. (F) OT-II T cells (4.5×10⁴ cells) were cultured alone or co-cultured with BM-DCs (4.5×10³ cells) pulsed with OVA peptide and/or MUC1 peptide. Twenty-four hours (A–D) or 48 hours (E, F) after the initiation of co-cultures, supernatants were collected, and the concentration of IL-2 was measured by ELISA. Data are shown as the mean±SD (n = 3 or 4). Statistical analysis was performed using the Student’s t-test (n.s.: not significant). A representative result from three independent experiments is shown.