CD19 and rheumatoid arthritis: A total of 86 patients with RA (RA group) and 50 healthy controls (HC) were included in the study. The immune cells of CD4+, CD19+ B, NK, Th17, Treg, ILCs, and their subsets (i.e., ILC1s, ILC2s, and ILC3s) were characterized in peripheral blood mononuclear cells by flow cytometry.