Figure 1.

Metabolism drives immune cell function. Glucose is metabolized by glycolysis, which is essential for activated NK cells, T cells, B cells, dendritic cells (DCs), M1 macrophages and granulocytes. Pyruvate can be converted to lactate and secreted from the cell or else it can be converted to acetyl CoA which feeds into the TCA cycle. The TCA cycle results in the production of reducing equivalents (NADH, FADH) which feed into the electron transport chain. The electron transport chain uses the electrons supplied by NADH and FADH to pump protons across the inner membrane. This force is then used to drive ATP synthase which makes ATP. Oxphos is important for immune cells when they are at rest, and it is also essential for activated NK cells, T cells, M2 macrophages and B cells. Acetyl CoA can alternatively be supplied by fatty acids—this form of metabolism is important for memory cells, regulatory cells and M2 macrophages. Glutamine can feed into the TCA cycle via glutaminolysis—this pathway is used by T cells and to a lesser extent, NK cells.