Following a previous study, which showed the abundance of tissue-resident Tfh cells (CD3+CD4+CXCR5+PD-1+) in SMG lesions in patients with IgG4-RD (14), we examined the gene expression profile of GC-type Tfh cells (CD3+CD4+CXCR5hiPD-1hi) in IgG4-RD lesions and compared it with that of GC-type Tfh cells in tonsils (Figure 1A). The gene discussed is CD4; the disease is immunoglobulin G4-related sclerosing disease.