Toll-like receptor family (TLR) has a fundamental role in pathogen recognition and activation of innate immunity. TLRs are highly conserved from Drosophila to humans and share structural and functional similarities. TLRs recognize pathogen-associated molecular patterns (PAMP) that are expressed on infectious agents, and mediate the production of cytokines necessary for the development of effective immunity. Toll-line receptor 2 (TLR2) cooperates with LY96 to mediate the innate immune response to bacterial lipoproteins and other microbial cell wall components. TLR2 acts via MYD88 and TRAF6 to lead to NFkB activation, cytokine secretion and inflammatory response. TLR2 is highly expressed in peripheral blood leukocytes, in particular in monocytes, in bone marrow, in lymph node and in spleen. Genetic variations in TLR2 are associated with susceptibility to leprosy, due to Mycobacterium leprae infection.