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phages and Dendritic cells) in the lung. But only 5-10 % of infected people developed clinical symptoms probably due complex recognizes diacylated lipopeptides and bacterial LTA of Mycoplasmal compounds. TLR4 recognizes lipo-ingle nucleo-genes might ever, neither een reported Chen et al. BMC Pulmonary Medicine (2015) 15:57 DOI 10.1186/s12890-015-0049-4mate 5 kb. Its coding gene has two exons, and the majorDepartment of Tuberculosis, The 309th hospital of PLA, No. 17, Heishanhu Road, Haidian District, Beijing 100091, ChinaThe gene of toll-like receptor 9 is located on chromo-some 3p21.3. The total length of TLR9 gene is approxi- * Correspondence: chenzhidoctor@sina.comToll-like receptors (TLRs) are pattern recognizing re-ceptors (PRRs) and play an important role in regulating human’s immune system. The TLRs can recognize pathogen-associated molecular patterns (PAMPs) in both extracellular and intracellular environment. The TLRs have the ability to initiate signaling pathways that the exogenous MTB DNA as PAMPs [4]. S ing on TLR1, 2, 4 and 6 have found that s tide polymorphisms (SNPs) of these TLRs be associated with differential TB risk. How systematic review nor meta-analysis has b for TLR9 [3].to undermined immunity response [1]. polysaccharide (LPS) and TLR9 homodimer recognizes tudies focus-an increased risk. Conclusions: The meta-analysis indicated that rs352139 polymorphism might be associated with decreased TB risk in Indonesians whereas increased risk in Mexicans. Whether the observed association was due to causal effect needs to be further studied