Figure 4. Asl-deficient CD4⁺ T cells contain synthesized L-ARG.

(A) Experimental setup. Asl^WT or Asl^ΔHem P25k CD4⁺ T cells were co-cultured with P25-loaded Asl^WT or Asl^ΔHem BMDCs for 96h. Media contained 1mM ¹³C₅ L-ARG, ¹³C₅ L-CIT, or ¹²C₅ L-CIT. T cells were isolated by CD11c MACS and prepared for peptide or small molecule MS analysis. B) Percentage of total peptides containing ¹³C₅ L-ARG (gray hashed) or unlabeled (black). Data are mean±SD (N=3, 2 experiments). C) Percentage of ¹³C₅ L-ARG (gray hashed) or ¹²C₅ L-ARG (black) within total free L-ARG. Data are mean±SD (N=2, 2 experiments).