How decreasing T cell signaling unexpectedly results in autoimmunity.

In this issue of JEM, Tanaka et al. (2022. J. Exp. Med.https://doi.org/10.1084/jem.20220386) advance our understanding of how genetic mutants that decrease T cell recognition of antigen, a critical event for immune activation to invading microbes and virus, paradoxically results in autoimmunity.