CD4 and immunoglobulin G4-related sclerosing disease: The multiorgan tumor-like masses characteristic of IgG4-RD involve T follicular helper T cells (Tfh), CD4+ cytotoxic T lymphocytes (CTL), and IgG4+ PC, and lead to irreversible tissue damage (Chen et al., 2019; Katz and Stone, 2022; Maehara et al., 2023; Perugino and Stone, 2020).