CD4 and immunoglobulin G4-related sclerosing disease: In this study, we systematically analyzed the changes of CD4+CD28- CTLs, CD8+CD28- CTLs, and their related subpopulations in peripheral blood of IgG4-RD patients, and then clarified the effects of IL-7 on the proliferation and subpopulation composition of CTLs and its mechanism.