MR1 and systemic lupus erythematosus: By crossing FcγRIIb−/−Yaa mice (21), a spontaneous lupus mouse model, to MR1-deficient mice that lack MAIT cells, the current study demonstrates that MAIT cell deficiency results in reduced disease severity, as shown by decreased autoantibody production and lower glomerulonephritis scores, and that these effects are accompanied by reduced germinal center responses as well as reduced T cell and innate T cell responses in MR1-deficient lupus mice.