MAIT cells are able to respond to local cytokine signals as well as through TCR signals, and they can use both pathways to generate a diverse range of responses. Previously we have shown that for viruses and viral vector-based vaccines that MAIT cells are triggered rapidly and contribute to induction of immune responses and immune protection. The induction of these responses is driven by multiple cytokines, including eg Type I interferon, IL-12, IL-18 and TNF. TCR triggering alone can produce an alternative range of responses, including IL-10 production and some tissue repair features. Combining cytokine and TCR signals appears to unlock the full potential of human MAIT cells (eg for IL-17 production). In this talk I will discuss new data on these 3 types of triggering in relation to infection and homeostasis, with a focus on new data from influenza challenge models in WT and MR1 -/- mice, human vaccine cohort studies and in vitro analysis of the MAIT cell secretome.