Functionally distinct CD4+ helper T (Th) cell subsets, such as Th1, Th2, Th17, and regulatory T cells (Treg), play a pivotal role in the host-defense against pathogen invasion and the pathogenesis of inflammatory disorders. In this project, DIA-MS-based proteome analysis was performed on naïve CD4+ T, Th0, Th1, Th2, Th17 and iTreg cells using Q Exactive HF-X (Thermo Fisher Scientific) to search for proteins that differ among the cell subsets.