Figure 5. Only SIY and Tyr₃₆₉ are cross-presented, as detected by cytokine secretion by T cells stimulated by stromal cells isolated from untreated tumors.

CD11b⁺ stromal cells were isolated from established untreated tumors and were co-cultured with peptide-activated T cells. Enriched stromal cells from tumors grown from MC57-SIY, -hgp100 and -mgp100 cells (all grown in OT-I mice) and -TyrHHD (grown in AOTA mice (non-self)) were co-cultured with 2C pmel AFH (non-self) or FH (self) TCR-transgenic T cells. Stromal cells from the various tumors were compared to cultured cancer cells expressing the same antigen. Supernatants were harvested after 24 h of co-culture and amounts of IFN-γ and TNF-α measured by ELISA. Data are shown as percent of maximal cytokine secretion (anti-CD3 and -CD28 antibody stimulation, defined as 100 %). For TNF-α, cytokine secretion by stromal cells without T cells was subtracted to obtain specific TNF-α secretion by T cells (443 to 975 pg/ml by 1×10⁵ cells cultured in 200 µl for 24 h, depending on experiment). Unstimulated T cells served as negative control (below 0.7 % for all responders, not shown). Data shown are combined from two experiments and are representative for four independent experiments. See also Figure S4.

* not done