Figure 7. Metabolism of immune cell subtypes.

The various immune cell subsets exhibit a reliance on distinct metabolic pathways to promote cell survival, lineage generation and function. Inflammatory macrophages use glycolysis, the tricarboxylic acid (TCA) cycle, the pentose phosphate pathway, fatty acid synthesis and amino acid metabolism to proliferate and to support the production of inflammatory cytokines. M2 macrophages, which exhibit a more tolerant phenotype, use the TCA cycle, fatty acid oxidation and arginine flux into the arginase pathway. Rapidly proliferating effector T cells, including T helper 1 (T_H1), T_H17 and cytotoxic CD8⁺ T cells, use glycolysis, fatty acid synthesis and amino acid metabolism to promote proliferation and cytokine production. Immunosuppressive regulatory T (T_reg) cells use the TCA cycle and fatty acid oxidation. Similarly, memory CD8⁺ T cells also require the use of the TCA cycle and fatty acid oxidation to promote increased cell lifespan. ROS, reactive oxygen species.