Our laboratory studies the populations of lymphocytes that reside at mucosal barriers and perform rapid innate-like functions to maintain homeostasis and protect against infection, injury and tumor. We use developmental biology and genetic engineering to define the identity and track the function of multiple 'unconventional' populations including NKT cells, MAIT cells, gamma-delta T cells, innate lymphoid cells, intraepithelial intestinal T lymphocytes and IgA producing intestinal B cells. Ultimately, these studies help identify the central relationships between immunity and microbiome at the intestinal barrier.