Since binding of CD154 (CD40L) on T helper cells to CD40 on MDDC may further activate MDDC and induce a variety of downstream effects, our data suggested that a reduced capacity of MDDC primed by H. pylori to express CD40 may weaken the function of MDDC and the communication of MDDC to T helper cells in gastric cancer patients. The gene discussed is CD40; the disease is gastric cancer.