Phagocytosis is a cellular procedure for ingesting and eliminating particles larger than 0

Phagocytosis is a cellular procedure for ingesting and eliminating particles larger than 0. and phases involved in phagocytosis. mannose-capped lipoarabinomannan (ManLAM)-coated beads (25), while HeLa cells could bind and internalize bacteria (26). DC-SIGNR is another C-type lectin receptor with high homology to DC-SIGN, and capable of binding mannose-rich ligands (34). Therefore, DC-SIGNR is also very likely a phagocytic receptor. Other C-type lectin domain-containing proteins have been implicated in phagocytosis long before Dectin-1 and other C-type lectin receptors (6). The macrophage mannose receptor (CD206) presents several C-type lectin carbohydrate recognition domains, which detect -mannan on many microorganisms (Table 1). The mannose receptor was also been shown to be a real phagocytic receptor when indicated in non-phagocytic COS-1 cells. Transfected COS-1 cells had been then in a position HILDA to mediate internalization of zymosan (27). Desk 1 Human being non-opsonic phagocytic receptors Cenicriviroc and their ligands. Polysaccharides of some candida cells(19C21)MincleTrehalose dimycolate of Mycobacteria(22, 23)MCLTrehalose dimycolateMannose-rich glycans(24C26)Mannose receptorMannan(27)Compact disc14Lipopolysaccharide-binding proteins(28)Scavenger receptor ALipopolysaccharide, lipoteichoic acidity(29, 30)Compact disc36(30). Compact disc36 detects em Plasmodium falciparum /em -contaminated erythrocytes (31), and MARCO (macrophage receptor with collagenous framework) is involved with recognition of many bacteria (32). Receptors for Apoptotic Cells In multicellular microorganisms many cells pass away by apoptosis for maintaining homeostasis constantly. These apoptotic cells are removed by phagocytosis. Recognition of apoptotic cells needs particular receptors for substances that only show up on the membrane of dying cells. These substances consist of lysophosphatidylcholine, and phosphatidyl serine (PS) (36). These substances deliver to phagocytes an consume me sign (37). Receptors straight knowing PS consist of TIM-1, TIM-4 (38), stabilin-2 (39), and BAI-1 (brain-specific angiogenesis inhibitor 1) (40) (Table 2). The integrin v3 can also bind PS after other receptors, for example lactadherin, connect PS to the integrin (41). The integrin V5 (42), CD36 (45), and CD14 (44, 46) are also receptors for apoptotic cells (Table 2). Some normal cells, for example activated B and T lymphocytes, may express significant levels of PS on their surface. These cells avoid phagocytosis by expressing at the same time molecules that serve as don’t Cenicriviroc eat me signals (2). One such molecule is CD47, a ligand to the receptor SIRP (signal regulatory protein ), which is expressed on phagocytes (47). Upon engagement, SIRP delivers an inhibitory signal for actin assembly (47). The signaling events from these receptors to activate phagocytosis are just beginning to be elucidated. Since phagocytosis of apoptotic cells is central to homeostasis (48), determining the phagocytosis mechanisms of all these receptors for apoptotic cells will be an active area of future research. Table 2 Receptors for apoptotic cells. thead th valign=”top” align=”left” rowspan=”1″ colspan=”1″ Receptor /th th valign=”top” align=”left” rowspan=”1″ colspan=”1″ Ligands /th th valign=”top” align=”left” rowspan=”1″ Cenicriviroc colspan=”1″ Reference(s) /th /thead TIM-1*Phosphatidylserine(38)TIM-4*Phosphatidylserine(38)Stabilin-2Phosphatidylserine(39)BAI-1*Phosphatidylserine(40)Lactadherin and V3MFG-E8*(41)V5Apoptotic cells(42)CD36Oxidized lipids(43)CD14Phosphatidylserine (?)(44) Open in a separate window * em TIM, T cell immunoglobulin mucin; BAI-1, brain-specific angiogenesis inhibitor 1; MFG, milk fat globule /em . Opsonic Receptors Foreign particles can also be labeled for phagocytosis by opsonins, which are host-derived proteins that bind specific receptors on phagocytic cells. Important opsonins promoting efficient phagocytosis include antibody (IgG) molecules and complement components. These opsonins and their receptors are the best studied so far (Table 3). Table 3 Individual opsonic phagocytic receptors and their ligands. thead th valign=”best” align=”still left” rowspan=”1″ colspan=”1″ Receptor /th th valign=”best” align=”still left” rowspan=”1″ colspan=”1″ Ligands /th th valign=”best” align=”still left” rowspan=”1″ colspan=”1″ Guide(s) /th /thead FcRI (Compact disc64)IgG1 = IgG3 IgG4(49)FcRIIa (Compact disc32a)IgG3 IgG1 = IgG2(49)FcRIIIa (Compact disc16a)IgG(49)FcRI (Compact disc89)IgA1, IgA2(13, 50)CR1 (Compact disc35)Mannan-binding lectin, C1q, C4b, C3b(51)CR3 (M2, Compact disc11b/Compact disc18, Macintosh-1)iC3b(52)CR4 (V2, Compact disc11c/Compact disc18, gp190/95)iC3b(52)51 (Compact disc49e/Compact disc29)Fibronectin, vitronectin(53) Open up in another home window Fc Receptors Fc receptors (FcR) are glycoproteins that particularly bind the Fc component of IgG substances (12, 54). When FcR indulge IgG substances in multivalent antigen-antibody complexes, they obtain clustered in the membrane from the cell, and cause phagocytosis as then.