Figure 5. Coherent feed-forward loop regulation of IL-2 secretion.
(A and B) 3 × 104 5C.C7 TCR-transgenic Rag2−/− T cells co-cultured with 3.5 × 105 APCs pre-pulsed with 500 nM K5 antigen. (A) Blocking of cognate pMHC ligand via administration of 20 μg/ml α-I-Ek antibody at varied time points during IL-2 production causes a rapid drop (detected here within 2 hr) in the number of IL-2-producing cells. (B) Addition of K5 antigen at t = 22 hr to cultures increases the numbers of IL-2-producing cells. (C) Phosphorylation of STAT5 is rapidly enhanced upon blocking of cognate pMHC ligand via administration of 20 μg/ml α-I-Ek antibody. (D) Cells activated with 1 μM of K5 antigen were treated with a JAK inhibitor or carrier control at 9 hr. Cells of each condition were then treated with antigen-blocking reagent anti-I-Ek or control anti-H2-Db at 30 hr. IL-2 production was measured via cytokine capture assay. All conditions performed in triplicate. (E) Sketch of the antigen-driven inhibition of IL-2 signaling (red), which makes IL-2 production contingent on antigen availability.