Stimulatory effects of Helicobacter pylori on human peripheral blood mononuclear cells of H. pylori infected patients and healthy blood donors.

The ability of 23 different strains of Helicobacter pylori to induce proliferative response of human peripheral blood mononuclear cells (PBMC) was investigated. All tested strains stimulated the DNA synthesis of PBMC from both healthy and H. pylori infected blood donors, but with lower stimulation of PBMC of infected donors. Using different bacterial antigen preparations, such as crude membranes, cytoplasmic proteins, and urease, a significantly lower induction of the proliferative response of PBMC from H. pylori infected than from healthy blood donors could also be demonstrated. In contrast to this result the reaction to phytohemagglutinin and purified protein derivative of tuberculin was similar in both groups. The stimulation pathway was interleukin 2 (IL-2) dependent as proved by inhibition of the proliferative response with an alpha-IL-2-receptor antibody. Using an antibody against HLA-DR the lymphoproliferation could also be blocked showing the importance of the major histocompatibility class II (MHCII) complex. Only coincubation of T cells with monocytes plus antigen or with antigen-preincubated monocytes led to a proliferative response showing the necessity of antigen-presenting cells. At least a part of the lymphoproliferative response is MHCII restricted as could be shown with H. pylori specific T-cell lines. These results and the kinetics of the proliferative response with a maximum at day 7 suggest that the proliferative response of human PBMC was mainly induced by antigens than by a mitogen.