Figure 5.

Increased Intracellular L-Arginine Levels Endow Mouse T Cells with a High Survival Capacity In Vitro and In Vivo

(A) BALB/c CD90.1⁺ CD4⁺ TCR transgenic T cells specific for the influenza HA_110–119 peptide were adoptively transferred into CD90.2⁺ host mice that were then immunized subcutaneously (s.c.) with HA_110–119 in complete Freund’s adjuvant (CFA). Mice were fed with L-arginine-HCl (1.5 mg/g body weight) or PBS, administrated daily starting 1 day before immunization. Fifteen days later, the amount of CD44^hi CD90.1⁺ CD4⁺ TCR transgenic T cells in draining lymph nodes was measured by fluorescence-activated cell sorting (FACS) analysis; n = 9 from two independent experiments.

(B and C) In vitro T cell survival experiment with C57BL/6 wild-type (WT) or Arg2^–/– T cells. Naive CD62L^hi CD44^lo CD4⁺ T cells and CD8⁺ T cells were activated for 4 days in L-Arg or Ctrl medium in the absence or presence of the arginase inhibitor norNOHA (500 μM). On day 2 exogenous IL-2 was added to the cultures, on day 4 cells were washed extensively and cultured in medium without IL-2. Shown is the difference in the percentage of living CD4⁺ (B) and CD8⁺ (C) T cells relative to WT T cells as determined by Annexin V staining 2 days after IL-2 withdrawal. WT, n = 6-19; WT norNOHA, n = 6–8; Arg2^–/–, n = 4–6; Arg2^–/– norNOHA, n = 4.

(D) Equal numbers of CD45.1⁺ WT and CD45.2⁺ CD90.2⁺Arg2^–/– naive CD8⁺ T cells were transferred into CD45.2⁺ CD90.1⁺ host mice. Mice were immunized with the OVA_257–264 peptide in CFA. Fifteen days after immunization, the amount of OVA_257–264-specific CD44^hi CD8⁺ T cells was measured in draining lymph nodes by flow cytometry using OVA_257–264/H-2Kb multimers; n = 4. One representative experiment out of two performed. ^∗p < 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001, ^∗∗∗∗p < 0.0001 (Student’s t test).

Error bars represent SEM throughout.

See also Figure S5.