The stimulation and inhibition of T cell proliferation by Helicobacter pylori components

The purified T cells from peripheral blood of healthy human volunteers, seronegative for anti-Helicobacter pylori antibody were stimulated in cultures with live or heat-killed H. pylori rods or with bacterial sialic acid-specific surface haemagglutinin (sHA), a crude surface (SF) or cytoplasmic (CF) fractions. It is demonstrated that H. pylori bacteria contain both stimulatory and inhibitory components for T cells of healthy individuals. The sHA as well as SF (5-20 micrograms) induced the proliferative response of T lymphocytes. By contrast, CF inhibited in dose dependent manner, the proliferation of T cells in the cultures stimulated with H. pylori bacteria or PHA. The result suggest that in vivo, a dominance of activation or immunosuppression could depend on the concentration of the bacteria and their products in infective foci.