Immunohistological analysis of rectal biopsies from Shigella-infected patients revealed extensive synthesis of a number of proinflammatory cytokines (IL-1α, IL-1β, IL-6, TNF-α and IFN-γ) at the local site of infection during the acute phase and increasing frequencies of cytokine-producing cells correlated with increasing severity of the disease. This evidence concerns the gene IL1B and infection.