T-cell regulation in helminth parasite infections: implications for inflammatory diseases.

The field of infectious disease immunology is at an exciting intersection with new concepts in immune regulation meeting with the dynamics of infectious diseases. We discuss how the identification of regulatory mechanisms has already helped develop new models to understand helminth infections, which remain among the most prevalent chronic diseases in the world today. The epidemiological imbalance between helminth infections in developing countries, and intensifying allergies and autoimmune pathologies in the industrialised nations, seems to reflect a fundamental shift in regulation of immune responsiveness. Experimental studies have verified that helminths can downmodulate a range of immunopathological conditions, with the regulatory T cell being one of the most common mechanisms in play. We discuss further the context of host genetic predisposition, together with the impact of infection on the evolution of the human immune system, and suggest future strategies to harness our new understanding of helminth organisms in order to control both infectious and non-infectious immunological disorders.