id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
en-wikipedia-org-9224		Immune system - Wikipedia			.html	text/html	13768	2190	62	Natural killer cells (NK) are lymphocytes and a component of the innate immune system which does not directly attack invading microbes.[41] Rather, NK cells destroy compromised host cells, such as tumor cells or virus-infected cells, recognizing such cells by a condition known as "missing self." This term describes cells with low levels of a cell-surface marker called MHC I (major histocompatibility complex)—a situation that can arise in viral infections of host cells.[42] Normal body cells are not recognized and attacked by NK cells because they express intact self MHC antigens. These cytokines and other chemicals recruit immune cells to the site of infection and promote healing of any damaged tissue following the removal of pathogens.[48] The pattern-recognition receptors called inflammasomes are multiprotein complexes (consisting of an NLR, the adaptor protein ASC, and the effector molecule pro-caspase-1) that form in response to cytosolic PAMPs and DAMPs, whose function is to generate active forms of the inflammatory cytokines IL-1β and IL-18.[49]	./cache/en-wikipedia-org-9224.html	./txt/en-wikipedia-org-9224.txt