CD40 and systemic lupus erythematosus: In addition, shortage of CD40 rs4810485 T in RA and SLE is due to decreased expression of CD40 in peripheral blood mononuclear cells and B cells, while sustained expression of CD40L and elevated expression of CD40 in RA and SLE patients are the main causes of enhanced activation of humoral and cellular immunity, activation of non-cellular immune target, and eventually disease [36].