Table 1.

Host immune receptors interacting with Mtb ligands and the consequences.

PRR class	Receptor name	Mtb ligand	Secreted cytokines	Functions
Toll-like receptor	TLR2	di-(TLR2/TLR6) or tri-(TLR2/TLR1) acylated lipoproteins, 19-kDa lipoprotein, LprA, LprG, LprE, rLrp, 30-kDa antigen, 38-kDa antigen, MymA, PPE18, PPE-57, heat shock protein 60, MTP83, Rv1509, Rv2659c, Rv1738, Rv2627c, Rv2628, ESAT-6, LAM, LM, ManLAM, and PIM.	IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-22, TNF-α, TGF-β, MCP-1, and IFN-γ.	Generation of RNS and ROS, apoptosis, T-cell priming, induction of Th cell responses, and evoking immunological memory response.
	TLR3	dsRNA and tRNA.	IL-10 and IL-12.	Boosting TLR8 signaling.
	TLR4	Heat shock proteins, 38-kDa antigen, RpfE, Rv0652, Rv0335c, Rv2659c, Rv1738, Rv2627c, Rv2628, GrpE, and HBHA.	IL-1β, IL-2, IL-6, IL-8, IL-10, IL-12, IL-17, IL-23, TNF-α and IFN-γ.	Dendritic cell activation, MHC I and II antigen processing, boosting Th1 and Th17 mediated response, autophagy, and apoptosis.
	TLR7	ssRNA	IFN-α and IFN-β.	Autophagy
	TLR8	tRNA and phagosomal RNA	IL-12, IL-18 and IFN-γ.	Autophagy
	TLR9	dsDNA	TNF-α, IFN-α and IFN-β.	Induction of Th1 response And MHC-I-Ag cross-processing.
NOD-like receptor	NOD2	Muramyl dipeptide	IL-1β, IL-6, IL-8, IL-10, IL-12, TNF-α, CXCL-2, CCL-5, and MCP-1.	Generation of RNS, autophagy, potentiation of TLRs.
	NPLR3	dsDNA	IL-1β	Inflammasome activation
C-type lectin receptor	Dectin-1	Unknown	IL-1β, IL-2, IL-10, IL-12, IL-17, IL-23, TNF-α, IFN-γ, and CXCL2.	Phagocytosis, dendritic cell maturation, respiratory burst, and production boosting Th1 and Th17 mediated response.
	Dectin-2	ManLAM	IL-1, IL-2, IL-6, IL-12, IL-17, TNF-α, IFN-γ and MIP-2.	DC maturation and boosting Th17.
	Mincle	TDM, TMM	IL-1α, IL-1β, IL-6, IL-8, IL-10, TNF-α, and G-CSF.	Autophagy, production of NO and ROS, delaying phagosome maturation and stimulating surface CD11b expression.
	MCL	TDM	IL-1β, IL-6, MIP-2 and TNF-α	Phagocytosis, inhibition of NLRP3 inflammasome activation, respiratory burst, and stimulating the expression of Mincle.
	DCAR	PIMs	IL-12 and IFN-γ.	Stimulating Th1 response.
	CR3	LAM and PIM		Opsonic and non-opsonic phagocytosis.
	DC-SIGN	LAM, ManLAM, PIM, α-glucan, 19 kDa, 38 kDa and 45 kDa antigens.	IL-6, IL-10, IL-12, and CXCL-8.	Th1 and Th17 response inhibition.
	MR	ManLAM, PIM, LM, 38‐kDa glycoprotein, 19-kDa antigen, and other mannosylated proteins		Phagocytosis, inhibition of phagolysosome fusion, and inhibition of Th17 response.
	DCIR	Unknown		Inhibition of TLR signaling.
	SP-A	ManLam, LM, 60-kDa glycoprotein and glycoprotein Apa.	IL-10 and TGF-β1	Agglutination, phagocytosis, induction of MR expression, and suppression of NO and ROS.
	SP-D	LAM, LM and PILAM		Inhibition of phagocytosis and enhancing phagolysosome fusion.
	MBL	ManLAM		Complement activation.
Scavenger receptors	SR-A	TDM	IL-4 and TNF-α.	Phagocytosis and suppression of Th1 response.
	MARCO	TDM	IL-1β, IL-6, and TNF-α.	Phagocytosis, autophagy, and production of ROS and RNS.
	SR-B1	ESAT-6		Transcytosis of Mtb across microfold cells.
	CD36	ManLAM and LM	TNF-α	Suppression of NO and promoting lysosomal dysfunction.
	CD163			Disease biomarker.
	AIM			Production of ROS and antimicrobial, and autophagy.
Absent in Melanoma receptor	AIM2	ssDNA	IL-1β and IL-18.	Inflammasome activation, autophagy, and boosting Th1 response.
Aryl hydrocarbon receptor (AhR)		Naphthoquinone phthiocol		Inhibition of phagocytosis.
CD14		Chaperonin 60.1	IL-1β, TNF-α, IL-6, IL-8, and IL-12	Phagocytosis and facilitating signaling of TLR2 and MARCO.
Triggering receptor expressed on myeloid cells 2 (TREM-2)				Proinflammatory Th1 response
Macrophage galactose-type lectin (MGL)-1				T-cell mediated control of Mtb
Retinoic acid inducible gene I (Rig-I)		RNA	IFN-β
Galectins	Galectin-3			Autophagy
	Galectin-8			Autophagy
	Galectin-9			Autophagy