Protection versus pathology in tuberculosis: recent insights

Recent studies have revisited the roles of prime players in the immune response to tuberculosis (TB) and have highlighted novel functions of these players. Specifically, immunoregulatory mechanisms mediated by IFN gamma have been delineated as well as a novel role for neutrophils in promoting antigen presentation. New insights into the interaction between the bacterium and phagocyte indicate that the bacterium actively promotes phagocyte necrosis rather than apoptosis and that this impacts generation of the acquired response. There are also many new examples of how the phagocyte responds to the bacteria and how it mediates control. The phenotype of protective T cells is also being re-examined. These developments provide promise for improved vaccine design and highlight the complexity of this disease.