ABSTRACT

Tuberculosis (TB) remains a global problem that results in as many as 2 million deaths each year. TB infects innate immune cells patrolling the lung. A live-attenuated Mycobacterium bovis Bacillus Calmette-Guerin (BCG) strain is the only strain used in vaccines against tuberculosis. However, its efficacy remains controversial. Dendritic cells (DCs) are the major antigen-presenting cells in the induction of a cellular response to intracellular pathogens, such as mycobacteria. DCs possess the ability to induce both innate and adaptive immune responses. In the context of human infection, little is known about DC−BCG interaction. In this review, we focus on BCG interactions with human DCs with regard to the role of DCs receptors in BCG recognition and the significance of the pro-inflammatory cytokines produced by BCG-infected DCs, especially interferon-γ−producing cells. Insights into human DC responses to BCG are necessary for a better understanding of the lack of a protective response to the current BCG vaccine and for developing new effective anti-TB immunotherapeutics and vaccine strategies.