Lipids are not only a central part of human metabolism but also play
diverse and critical roles in the immune system. As such, they can act as
ligands of lipid-activated nuclear receptors, control inflammatory signaling
through bioactive lipids such as prostaglandins, leukotrienes, lipoxins,
resolvins, and protectins, and modulate immunity as intracellular phospholipid-
or sphingolipid-derived signaling mediators. In addition, lipids can serve as
antigens and regulate immunity through the activation of lipid-reactive T cells,
which is the topic of this review. We will provide an overview of the mechanisms
of lipid antigen presentation, the biology of lipid-reactive T cells, and their
contribution to immunity.