Table 3.

Summary of MHC class I molecules expressed/secreted on/by macrophages/tumor associated macrophages, their related ligands on immune cells and the function of their interaction

MHC (macrophage/	RECEPTOR (immune	FUNCTION	References
TAMs)	cells)
Membrane HLA-A-B-C	ILT2 on NK cells	- Negative regulation of INFgamma secretion	- Morel E. 2008 [133]
	ILT2 on T cells	- Negative regulation of T cell function	- Dietrich J. 2001 [136]
Membrane HLA-A-B	KIR3DL1/2 on NK cells and effector T cells	- Inhibition of cytolitic function	- Anfossi N. 2004 [93]
			- Long E.O. 2008 [94]
Membrane HLA-C	KIR2DL1/2/3 on NK cells and effector T cell	- Inhibition of cytolitic function	- Colonna M. 1993 [92]
			- Falk C.S. 1995 [132]
Membrane HLA-G1		- HLA-G1 is acquired through trogocytosis by CD4+ and CD8+ T cells resulting their temporarily reversion to regulatory T cells	- LeMaoult J. 2007 [143]
Soluble HLA-G5	ILT2 and ILT4 on myeloid APC	- secretion of the cytokine TGF-beta1 that contributes to T cells peripheral tolerance	- McIntire R.H. 2004 [122]
		- Turning down myeloid APC activation level	- Jones D.C. 2011 [79]
	KIR2DL4 on CD56bright NK cells	- Secretion of pro-angiogenic cytokines and chemokines	- Rajagopalan S. 1999 [147]
			- Rajagopalan S. 2012 [96]
	CD8 on activated CD8+ T cells and CD8+ NK cells	- Fas/Fas ligand mediated cell death	- Contini P. 2003 [145]
			- Puppo F. 2002 [146]
			- LeMaoult J. 2004 [144]
Membrane HLA-E	CD94/NKG2A on NK cells and cytotoxic T cells	- Production of immune-suppressive cytokines (IL-10 and TGF-beta1) by NK cells	- Jinushi M. 2004 [148]
		- Inhibition of cytolitic function	- Braud V.M. 1998 [46]
			- Borrego F. 1998 [102]

MHC class I molecules can be used by TAMs to promote tumor angiogenesis and to dampen immune response against tumor cells both directly inhibiting NK and T cells function and indirectly inducing the secretion of immunosuppressive cytokines.