NORMAL INTERLEUKIN-12 PRODUCTION IN INDIVIDUALS WITH ANTIBODIES TO HELICOBACTER-PYLORI

It is increasingly recognized that the inability of the immune system to clear H. pylori infection is caused by an inadequate immune respons e and is associated with chronic gastric inflammation, To further inve stigate the cellular immune response to H. pylori, we studied PBMC fro m 31 H. pylori antibody-negative and 16 H. pylori antibody-positive in dividuals for H. pylori-induced DNA synthesis, secretion of the Th1-ty pe cytokine IFN-gamma and secretion of IL-12, a cytokine produced by b acteria-stimulated monocyte/macrophages and a potent inducer of antiba cterial immune responses and Th1-type T cells. All experiments were pe rformed using Y. enterocolitica 03 as control. Our results demonstrate that DNA synthesis, IFN-gamma production and IL-12 production induced by H. pylori or Y. enterocolitica 03 did not differ significantly bet ween H. pylori antibody-positive and H. pylori antibody-negative indiv iduals. However, in the H. pylori-positive group there was a tendency, although not statistically significant, to produce less IFN-gamma in response to H. pylori but not Y. enterocolitica. These results demonst rate that monocyte/macrophages from H. pylori-positive individuals sec rete normal amounts of IL-12 upon bacterial challenge and suggest that the decreased production of IFN-gamma in H. pylori-positive individua ls observed in previous studies is selective for H. pylori and not cau sed by decreased IL-12 secretion.