Cytokine release induced by killed bacteria associated with anti-IFN-γ antibody in Shigella infection

An effort was made to analyze the effect of in vitro stimulation on macrophages using killed Shigella dysenteriae type-1 (KSD1) coupled with anti-Interferon Gamma (anti-IFN-γ) antibody. The stimulated macrophages were co-cultured with primed or non-primed T-cells from Shigella infected patients. T-cell cultures were also established by co-culturing KSD1 coupled with or without PHA stimulated macrophages. Emulsified KSD1 coupled with anti-IFN-γ antibody was found to act as a potent immunogen, inducing the release of Th1 cytokine from primed T-cells cultured in acute stage of the disease. It was observed that the levels of IFN-γ and IL-2 production rather than IL-4 and IL-6 were increased as the disease became more severe. On comparison, the subsequent values of IL-6, IFN-γ, IL-4 and IL-2 were found to be less significant in healthy primed T-cell cultures. This was also associated with a substantial production of superoxide ions (O2−), which probably inhibits the colonization of intracellular Shigella due to the presence of anti-IFN-γ antibodies. On the other hand KSD1 with or without PHA failed to induce such responses. The above findings reflect that in the presence of anti-IFN-γ antibody, KSD1 acts as a potential immunogen for eliciting cellular immunity against shigellosis.