Exercise Increases MAIT Cell Cytokine Expression but not Activation or Homing Markers

Mucosal associated invariant T (MAIT) have properties of both the innate and adaptive immune systems but are an understudied population within exercise immunology. These lymphocytes aggregate at the mucous membranes, but it is unknown if submaximal exercise alters their circulating numbers or function. PURPOSE To determine the MAIT cell response to submaximal exercise on activation and homing marker expression and stimulated cytokine production. METHODS Twenty healthy, young, recreationally active males cycled for 40 min at 86% of VT following an overnight fast. Peripheral blood mononuclear cells were isolated and labelled to identify specific MAIT cell populations using flow cytometry. Cytokine production following stimulation was also determined. RESULTS MAIT cells were 2.9% of T-cells and increased to 3.9% after exercise and with recovery whereas cell numbers significantly increased by 91.5% following exercise before returning to resting levels. Chemokine and activation marker absolute cell number significantly increased while expression levels remained constant but the high levels of CCR5 may help direct MAIT cells to sites of inflammation. Following stimulation, TNFα expression significantly increased after exercise before returning to baseline with a similar trend for IFNγ. CONCLUSIONS MAIT cell numbers undergo a partial biphasic response following submaximal exercise and appear to be preferentially mobilized within T-cells; however, the magnitude of the submaximal response was attenuated relative to maximal exercise. Stimulated MAIT cells increase TNFα expression, indicating greater responsiveness to pathogens following acute exercise. Corresponding Author: Erik D. Hanson, PhD, Department of Exercise and Sport Science, CB#8605, 315 Woollen Gym, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, Phone: 919.962.0816. Email: edhanson@email.unc.edu Funding sources: Junior Faculty Development Award (EH); University Research Council Award (EH) from the University of North Carolina. The UNC Flow Cytometry Core Facility is supported in part by P30 CA016086 Cancer Center Core Support Grant to the UNC Lineberger Comprehensive Cancer Center. Research reported in this publication was supported by the Center for AIDS Research award number 5P30AI050410. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation, and do not constitute endorsement by ACSM. The authors have no conflict of interest to report. Accepted for Publication: 31 August 2018. © 2018 American College of Sports Medicine

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