Table 1.

Components of innate immunity that recognize a Xenograft.

Immune Response	Component	Rejection Mechanism	Target Gene Editing	Rejection Period
Innate	Complement alternative pathway	Inhibits complement activation	factor H	HAR
	Complement regulatory proteins	Complement regulation	hCD55; hCD46; hCD59 expression	HAR; AVR
	Natural antibody	Reduces natural anti- αGal and non-Gal antibodies responses	GGTA1-KO; CMAH-KO; β4GALNT2-KO	HAR; AVR
	Platelet/Thrombin	Coagulation/thrombosis reduction	Human Thrombomodulin; human CD39 expression	AVR
	Macrophage	Macrophages regulation	hCD47 expression (a marker for “self”); human signal regulatory protein alpha expression; human heme oxygenase 1 expression; human A20 expression; human CD39 expression.	AVR
	NK cell	Natural NK cells regulation	human HLA-G, HLA-E expression; human beta2 microglobulin expression	AVR
	Neutrophil	Neutrophils regulation	Integrins	AVR

Abbreviations: αGal, galactose alpha-1,3-galactose; αGalT-KO, alpha1,3-galactosyltransferase-knockout; MHC: major histocompatibility complex; NK, natural killer; HLA, human leukocyte antigen; hCD47, human CD47; HAR, hyperacute rejection; AVR, acute vascular rejection.