Figure 5. BMDC-synthesized L-ARG is found within the extracellular milieu and fuels CD4⁺ T cell viability and proliferation.

(A) L-ARG and L-CIT concentration in supernatants collected from co-cultures of Asl^ΔHem CD4⁺ T cells with Asl^WT or Asl^ΔHem BMDCs originally in media containing 1mM L-CIT. Data are mean+SD (N=5, 2 experiments). (B-D) CTV-stained Asl^ΔHem CD4⁺ T cells were stimulated with α-CD3/CD28 and IL-2 for 96h. Media contained supernatants from Asl^ΔHem CD4⁺ T cells co-cultured with Asl^WT (black) or Asl^ΔHem (white) BMDCs originally supplemented 1mM L-CIT. (B) Representative live CD4⁺ T cell proliferation histograms. Graphical representation of live (C) and divided (D) cells. Data are mean+SD (N=6, 2 experiments). ***p < 0.001 by Student’s t-test.