Role of NK Cells in Tuberculous Pleurisy as Innate Promoters of Local Type 1 Immunity with Potential Application on Differential Diagnosis

An efficient host immune response against pathogens encompasses both fast acting innate immunity as well as slower, but more specific, adaptive immunity. The innate immune system is diverse and comprises a variety of cells including natural killer (NK) cells, neutrophils, macrophages, dendritic cells (DCs), as well as soluble factors such as complement. The adaptive immune response is typified by antigen-specific T and B lymphocytes that provide long-lasting protection known as immunological memory. While these two systems are often discussed separately, neither arm of the immune system works in isolation (Medzhitov & Janeway, 1999). The succession of cells interacting with Mycobacterium tuberculosis (Mtb) comprises tissue macrophages (MΦ) and dendritic cells (DC) followed by chemokine-attracted immigrating neutrophils and monocytes, and then activation and recruitment of natural killer (NK) and ┛├ T cells, followed by effector T lymphocytes primed in the draining lymph nodes (Ulrichs & Kaufmann, 2006).