Human MAIT cells in circulation are at the initial glance relatively homogenous regarding phenotype and function. However, recent findings by us and others have indicated that tissue localization and factors in the microenvironment strongly influence their functional response profiles. To study this in more detail, we investigated MAIT cells isolated from donor-matched tissue samples to determine MAIT cell characteristics across individuals and throughout human body sites. We investigate the impact of tissue localization on the transcriptional profile and clonal distribution between tissue sites. Further, we are working to assess how the state of the MAIT cell pool locally is associated with inflammatory disease states in the intestines and the lung. Thus, our work in progress will provide insight into the function of human MAIT cells in tissues and provide a spatial dimension to our understanding of the MAIT cell compartment.