We dissected the mechanistic basis of IL-7 effects on CD4+CD28- CTLs and CD8+CD28- CTLs from IgG4-RD patients and demonstrated that tofacitinib, a selective JAK inhibitor blocking IL-7 signaling, significantly inhibited the expansion, proliferation, and function of these CTLs. The gene discussed is CD28; the disease is immunoglobulin G4-related sclerosing disease.