ABSTRACT
This chapter discusses the natural history of Tuberculosis (TB) and virulence factors, and then focuses on the major new developments in the pathogenesis of TB. Acquired immunity to Mycobacterium tuberculosis (MTB) infection will be discussed from the standpoint of animal studies; from in vitro studies of phagocytosis and T-cell-independent growth inhibition of MTB by mononuclear phagocytes; and from host-genetic influences on acquiring MTB infection and development of TB. The role of cytokines in macrophage activation and deactivation in the modulation of T-cell responses and in tissue damage and granuloma formation will be considered. The contribution of cytokines and various pathways to MTB infection and growth containment is described below. Whether the suppression of T-cell responses was a consequence of cytotoxicity for Ag-presenting cells or direct suppression of T-cell responses was not resolved by this study. Exposure to an individual with active pulmonary TB carries a substantial risk of acquiring infection.
