Many studies have shown that the production of various immunoglobulins (Ig) such as IgA, IgM, and IgG is closely associated with TFH cells which play important roles in various autoimmune diseases such as ITP, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and IgA nephropathy [22, 26–29]. Here, CD40LG is linked to rheumatoid arthritis.