Lastly, we found signals of T‐cell–T‐cell crosstalk via CC‐chemokine ligand 5 (CCL5) on CD8 TEM binding to C‐C chemokine receptor type 4/5 (CCR4/5)‐expressing T cells that might facilitate recruitment of helper and cytotoxic CD4+ T cells that have been shown to mediate inflammation in IgG4‐RD (Fig 2E–G) (Mattoo et al, 2016; Mattoo et al, 2017; Perugino et al, 2021). The gene discussed is CCR4; the disease is immunoglobulin G4-related sclerosing disease.