Preserved MAIT cell numbers and function in idiopathic CD4 lymphocytopenia.

Abstract

Mucosal-associated invariant T (MAIT) cells constitute a subset of unconventional, MR1-restricted T-cells involved in antimicrobial responses as well as inflammatory, allergic and autoimmune diseases. Chronic infection and inflammatory disorders as well as immunodeficiencies are often associated with decline and/or dysfunction of MAIT cells. Herein, we investigate the MAIT cells in patients with idiopathic CD4 + lymphocytopenia (ICL), a syndrome characterized by consistently low CD4 T-cell counts (<300 cell/µL) in the absence of HIV infection or other known immunodeficiency, and by susceptibility to certain opportunistic infections. The numbers, phenotype and function of MAIT cells in peripheral blood were preserved in ICL patients compared to healthy controls. Furthermore, administration of IL-7 to ICL patients expanded the CD8 + MAIT cell subset, with maintained responsiveness and effector functions after IL-7 treatment. In conclusion, ICL patients maintain normal levels and function of MAIT cells preserving some antibacterial responses despite the deficiency in CD4 + T cells.