CRP and immunoglobulin G4-related sclerosing disease: The CART model revealed that the key process fluctuations leading to a diagnosis of IgG4-RD in this process were the serum levels of IgG4, C-reactive protein (CRP), IgM, soluble interleukin-2 receptor (sIL-2R), complement 3, lymphocytes, and IgG.