MR1-restricted T (MR1T) cells are part of a growing class of unconventional T cells that have emerged as important players in the early response to microbial infection. These cells, like other unconventional T cells, not only emerge from the thymus with immediate effector function, but also recognize non-peptide antigen produced by microbes. We show, using a panel of MR1T clones that share TCRa with differing TCRb chains, that the MR1T TCRb chain can contribute to recognition of both microbially infected dendritic cells, as well as distinguish between microbial ligand. These results suggest an important role in the TCRb chain in helping to sense microbial infection. However, given the wide range of antigen recognized by MR1T cells, as well as their capacity to produce inflammatory cytokines, and their enrichment in mucosal sites, likely in close proximity to commensals also capable of producing MR1T antigen, the question remains on how MR1T cell activation is regulated to prevent unwanted tissue damage or autoimmunity.