Figure 5. MR1T cells recognize diverse antigens not derived from RPMI 1640 medium.
Stimulation of the DGB129 MR1T cell clone by MR1-overexpressing (A) A375 cells (A375-MR1) and (B) THP-1 cells (THP1-MR1) grown for 4 days in RPMI 1640 or in PBS both supplemented with 5% human serum. Inhibition of T cell clone reactivity by anti-MR1 blocking mAbs (α-MR1) is shown. DGB129 cells recognize APCs loaded with fractions isolated from (C) THP-1 cell lysate or from (D) in vivo grown mouse breast tumor EMT6. Fractions E1 and E2 contain hydrophobic molecules; fractions N1-N4 contain hydrophilic molecules. (E) DGB70 MR1T cells react to N3 fraction of THP-1 lysate. (F) Stimulation of DGB129 and DGB70 T cells by THP-1-derived fractions N3 and N4 loaded onto plastic-bound recombinant MR1. Shown is T cell release of IFN-γ or GM-CSF mean ± SD of duplicate cultures (representative of three independent experiments). Total cytokine release is shown in panels A, B, F; fold increase over background is shown in panels C, D, E. *p<0.05 (Unpaired Student’s t-test).