Figure 4

Cytokine responses to A12-tetramer⁺ cells. DR1 mice were immunized with Ova (open bars), CII (solid bars), or A12 (hashed and striped bars), and the draining inguinal lymph node cells were selected to obtain the CD4⁺ populations. The A12-immunized lymph node cells were further fractionated into tetramer⁺ (left hashed bars) and tetramer^- (striped bars) populations. The cells were cultured (5 × 10⁵ CD4⁺ T cells/ml) with wild-type APC (DR1-positive splenocytes; 1:2 ratio) prepulsed in vitro with the immunodominant collagen peptide. Supernatants were collected and tested for the presence of each cytokine by using a multiplexed ELISA. The supernatants were collected from Ova-specific CD4⁺ T cells (open bars), CII-specific T cells (solid bars), DR1-A12 tetramer⁺ T cells (left hashed bars), or tetramer^- T cells (striped bars). Results shown represent the mean ± SD of three separate experiments and are expressed in picograms per milliliter of culture supernatants. The Th1/Th2 ratio was 13:1 in T cells responding to CII, whereas the Th1/Th2 ration was 0.5:1 in the DR1-A12 tetramer⁺ T cells.