L-arginine transfer from antigen presenting cells sustains CD4+ T cell viability and proliferation

Metabolomics analyses suggest changes in amino acid abundance, particularly L-arginine (L-ARG), occur in tuberculosis patients. Immune cells require L-ARG to fuel effector functions following infection. We have previously described an L-ARG synthesis pathway in immune cells, however its role in antigen presenting cells (APCs) has yet to be uncovered. Using a co-culture system with mycobacterial-specific CD4 + T cells, we show APC L-ARG synthesis supported T cell viability and proliferation, and activated T cells contained APC-derived L-ARG. We hypothesize APCs supply L-ARG to support T cell activation under nutrient limiting conditions. This work expands the current model of APC-T cell interactions and provides insight into the effects of nutrient availability in immune cells.