Molecular Mechanisms of Host–Pathogen Interaction: Entry and Survival of Mycobacteria in Macrophages

Abstract

Publisher Summary The components of the innate and adaptive immune systems and their functions, during an immune response against pathogens, are largely known today. Depending on the given microbe, the contributions of the individual host cell types and molecules to an effective immune response vary. Most microbes are recognized, killed, and degraded by first line innate immune mechanisms, without causing any symptoms of disease. Only the few longer persisting pathogens, which survive innate immunity, trigger adaptive immune responses that are based on molecularly well understood pathways of immunoglobulin receptor rearrangement, antigen processing and presentation, and T- or B-cell activation. Innate immunity as a first line defense system should act against all invading pathogens and, therefore, has made available a diverse repertoire of pathogen recognition molecules and mechanisms of elimination. The central innate immune cell—the macrophage—is equipped with a variety of recognition receptors, large phagocytic capacity, and a highly efficient killing and degradation machinery and is, therefore, a main mediator of anti-bacterial immune responses.