Oligolysine-based Oligosaccharide Clusters

Abstract

Dendritic cells are potent antigen-presenting cells that express several membrane lectins, including the mannose receptor and DC-SIGN (dendritic cell-specific ICAM-3-grabbing nonintegrin). To identify highly specific ligands for these dendritic cell receptors, oligosaccharides were converted into glycosynthons (Os1) and were used to prepare oligolysine-based glycoclusters, Os-[Lys(Os)]n-Ala-Cys-NH2. Clusters containing two to six dimannosides as well as clusters containing four or five pentasaccharides (Lewisa or Lewisx) or hexasaccharides (Lewisb) were synthesized. The thiol group of the appended cysteine residue allows easy tagging by a fluorescent probe or convenient substitution with an antigen. Surface plasmon resonance was used to determine the affinity of the different glycoclusters for purified mannose receptor and DC-SIGN, whereas flow cytometry and confocal microscopy analysis allowed assessment of cell uptake of fluoresceinyl-labeled glycoclusters. Dimannoside clusters are recognized by the mannose receptor with an affinity constant close to 106 liter·mol–1 but have a very low affinity for DC-SIGN (less than 104 liter·mol–1). Conversely, Lewis clusters have a higher affinity toward DC-SIGN than toward the mannose receptor. Dimannoside clusters are efficiently taken up by human dendritic cells as well as by rat fibroblasts expressing the mannose receptor but not by HeLa cells or rat fibroblasts expressing DC-SIGN; DC-SIGN-expressing cells take up Lewis clusters. The results suggest that ligands containing dimannoside clusters can be used specifically to target the mannose receptor, whereas ligands containing Lewis clusters will be targeted to DC-SIGN. Dendritic cells are potent antigen-presenting cells that express several membrane lectins, including the mannose receptor and DC-SIGN (dendritic cell-specific ICAM-3-grabbing nonintegrin). To identify highly specific ligands for these dendritic cell receptors, oligosaccharides were converted into glycosynthons (Os1) and were used to prepare oligolysine-based glycoclusters, Os-[Lys(Os)]n-Ala-Cys-NH2. Clusters containing two to six dimannosides as well as clusters containing four or five pentasaccharides (Lewisa or Lewisx) or hexasaccharides (Lewisb) were synthesized. The thiol group of the appended cysteine residue allows easy tagging by a fluorescent probe or convenient substitution with an antigen. Surface plasmon resonance was used to determine the affinity of the different glycoclusters for purified mannose receptor and DC-SIGN, whereas flow cytometry and confocal microscopy analysis allowed assessment of cell uptake of fluoresceinyl-labeled glycoclusters. Dimannoside clusters are recognized by the mannose receptor with an affinity constant close to 106 liter·mol–1 but have a very low affinity for DC-SIGN (less than 104 liter·mol–1). Conversely, Lewis clusters have a higher affinity toward DC-SIGN than toward the mannose receptor. Dimannoside clusters are efficiently taken up by human dendritic cells as well as by rat fibroblasts expressing the mannose receptor but not by HeLa cells or rat fibroblasts expressing DC-SIGN; DC-SIGN-expressing cells take up Lewis clusters. The results suggest that ligands containing dimannoside clusters can be used specifically to target the mannose receptor, whereas ligands containing Lewis clusters will be targeted to DC-SIGN. Dendritic cells are efficient antigen-presenting cells central to cellular immune responses (1Banchereau J. Steinman R.M. Nature. 1998; 392: 245-252Google Scholar). Internalized antigens are processed within the endosomal/lysosomal pathway for subsequent formation of MHC 1The abbreviations used are: MHC, major histocompatibility complex; Os, glycosynthons; BSA, bovine serum albumin; DABCO, 1,4- diazabicyclo[2.2.2]octane; ICAM-3, intercellular adhesion molecule 3; DC-SIGN, dendritic cell-specific ICAM-3-grabbing nonintegrin; DMEM, Dulbecco's modified Eagle's medium; PBS, phosphate-buffered saline; Glp, pyroglutamic acid; Flu, fluorescein-labeled; GM-CSF, granulocyte macrophage cell-stimulating factor; HPLC, high performance liquid chromatography; Rho, rhodamine Red-X™-labeled; RU, resonance units; CRDs, C-type carbohydrate recognition domains; Man, mannose; OBzl, O-benzyl ester. class II peptide complexes. Dendritic cell vaccination to elicit cellular responses rather than humoral responses requires peptide presentation with MHC I. Antigenic peptide loading onto class I MHC molecules in the endoplasmic reticulum requires the generation of peptides by the cytosolic proteasome and subsequent peptide transport into the endoplasmic reticulum. Dendritic cells express several endocytic receptors, including membrane lectins such as the mannose receptor and DC-SIGN (dendritic cell-specific ICAM-3-grabbing nonintegrin) that may be used to increase antigen presentation (2Figdor C.G. van Kooyk Y. Adema G.J. Nat. Rev. Immunol. 2002; 2: 77-84Google Scholar). The mannose receptor, first characterized in macrophages (3Stahl P.D. Rodman J.S. Miller M.J. Schlesinger P.H. Proc. Natl. Acad. Sci. U. S. A. 1978; 75: 1399-1403Google Scholar), binds and takes up glycoproteins and glycoconjugates containing terminal mannose, GlcNAc, or fucose (4Shepherd V.L. Lee Y.C. Schlesinger P.H. Stahl P.D. Proc. Natl. Acad. Sci. U. S. A. 1981; 78: 1019-1022Google Scholar). Calcium-dependent recognition of these sugars is mediated by C-type carbohydrate recognition domains (CRDs) in the extracellular region of the receptor (5Mullin N.P. Hitchen P.G. Taylor M.E. J. Biol. Chem. 1997; 272: 5668-5681Google Scholar). Glycoproteins internalized by the mannose receptor follow a well characterized endocytic path-way leading to lysosomes (6Stahl P.D. Wileman T.E. Diment S. Shepherd V.L. Biol. Cell. 1984; 51: 215-218Google Scholar). The cytoplasmic tail of the mannose receptor contains a tyrosine-based motif involved in the internalization process in association with clathrin-coated vesicles, and the mannose receptor traffics through early endosomes. Our experiments with fluorescein-labeled neoglycoproteins suggested that the mannose receptor is also expressed on monocyte-derived dendritic cells (7Avrameas A. McIlroy D. Hosmalin A. Autran B. Debré P. Monsigny M. Roche A.C. Midoux P. Eur. J. Immunol. 1996; 26: 394-400Google Scholar), and this finding was subsequently confirmed (8Engering A.J. Cella M. Fluitsma D.M. Hoefsmit E.C. Lanzavecchia A. Pieters J. Adv. Exp. Med. Biol. 1997; 417: 183-187Google Scholar). Recently, DC-SIGN, a new dendritic cell-specific membrane lectin was characterized (9Geijtenbeek T.B. Torensma R. van Vliet S.J. van Duijnhoven G.C. Adema G.J. van Kooyk Y. Figdor C.G. Cell. 2000; 100: 575-585Google Scholar). DC-SIGN binds the gp120 envelope glycoprotein on the surface of human immunodeficiency virus-1 (10Curtis B.M. Scharnowske S. Watson A.J. Proc. Natl. Acad. Sci. U. S. A. 1992; 89: 8356-8360Google Scholar). Its extracellular domain is a tetramer stabilized by an α-helical stalk, whereas its C-type CRDs bind high mannose oligosaccharides (11Mitchell D.A. Fadden A.J. Drickamer K. J. Biol. Chem. 2001; 276: 28939-28945Google Scholar). The presence of an internalization motif in its cytoplasmic tail suggests that DC-SIGN acts as an endocytic receptor, and it has been shown that complexes of DC-SIGN with an anti DC-SIGN antibody are targeted to late endosomes/lysosomes (12Engering A. Geijtenbeek T.B. van Vliet S.J. Wijers M. van Liempt E. Demaurex N. Lanzavecchia A. Fransen J. Figdor C.G. Piguet V. van Kooyk Y. J. Immunol. 2002; 168: 2118-2126Google Scholar). Therefore, in dendritic cells that express both the mannose receptor and DC-SIGN, the trafficking of an internalized glycosylated ligand will depend on its relative ability to bind each of these lectins. In search of synthetic ligands suitable for use in human therapy, we selected chemically defined compounds that should have low molecular weight and be recognized by either the mannose receptor or DC-SIGN with high affinity. Accordingly, we developed sugar clusters using disaccharides (13Bédouet L. Bousser M.T. Frison N. Boccaccio C. Abastado J.P. Marceau P. Mayer R. Monsigny M. Roche A.C. Biosci. Rep. 2001; 21: 839-855Google Scholar, 14Frison N. Marceau P. Roche A.C. Monsigny M. Mayer R. Biochem. J. 2002; 368: 111-119Google Scholar). These small multivalent synthetic glycopeptides were made by coupling glycosynthons (diglycosylpyroglutamyl-β-alanine derivatives (15Quétard C. Bourgerie S. Normand-Sdiqui N. Mayer R. Strecker G. Midoux P. Roche A.C. Monsigny M. Bioconjug. Chem. 1998; 9: 268-276Google Scholar)) onto a peptide containing up to five lysine residues. Such glycoclusters have previously been shown to bind various lectins with a high specificity. Glycoclusters containing lactose are taken up by HepG2 cells (13Bédouet L. Bousser M.T. Frison N. Boccaccio C. Abastado J.P. Marceau P. Mayer R. Monsigny M. Roche A.C. Biosci. Rep. 2001; 21: 839-855Google Scholar), a human hepatoma cell line expressing the galactose-specific lectin (16Schwartz A.L. Fridovich S.E. Knowles B.B. Lodish H.F. J. Biol. Chem. 1981; 256: 8878-8881Google Scholar) but not by dendritic cells, whereas those containing dimannosides are taken up avidly by dendritic cells but not by HepG2 cells (14Frison N. Marceau P. Roche A.C. Monsigny M. Mayer R. Biochem. J. 2002; 368: 111-119Google Scholar). This study describes the use of a series of glycoclusters made of or oligosaccharides containing either mannose or fucose to identify the ligands to recognition by either the mannose receptor or DC-SIGN. Surface plasmon resonance was used to determine affinity for the purified lectins on cytometry was used to by cells expressing either the mannose receptor or DC-SIGN. was and were and oligosaccharides were by Strecker were by coupling bovine serum with and disaccharides and with A.C. M. Midoux P. S. N. Monsigny M. J. Cell. Biochem. Scholar, M. Roche A.C. Midoux P. Biol. Cell. 1984; 51: Scholar). The of sugar BSA, by the M. C. Roche A.C. Biochem. Scholar), of affinity and was to be In to the containing mannose was also were purified by on a of either stabilized and with containing or or stabilized and with The flow was performance liquid was on a to a a was stabilized and with The flow was a was stabilized in the of in the compounds were using this for and a of in The flow was compounds were in with containing with containing was with a and of The first was to the (15Quétard C. Bourgerie S. Normand-Sdiqui N. Mayer R. Strecker G. Midoux P. Roche A.C. Monsigny M. Bioconjug. Chem. 1998; 9: 268-276Google Scholar) in a by coupling an with a in the presence of by to the on the was by The glycosynthons lactose and and are in Frison (14Frison N. Marceau P. Roche A.C. Monsigny M. Mayer R. Biochem. J. 2002; 368: 111-119Google Scholar). The were for the of glycosynthons oligosaccharides and and oligosaccharides and were as a that human in it is to a of we that were by as glycosynthons and substitution of the terminal sugar by a peptide N. L. Marceau P. C. Roche A.C. Mayer R. Monsigny M. Scholar). we were to prepare and use the and and of previously (14Frison N. Marceau P. Roche A.C. Monsigny M. Mayer R. Biochem. J. 2002; 368: 111-119Google Scholar), the purified glycosynthons were through an to and of the lysine of a peptide or The glycoclusters, were purified on a and by and by to the The cysteine residue was used to the the thiol group was made in the presence of and by with in a to the formation of leading to molecules were characterized by and of DC-SIGN or the HeLa cells expressing DC-SIGN were by of R. J. J. Immunol. 2000; Scholar), with an in the extracellular region of the HeLa human cells were in Dulbecco's modified Eagle's with bovine serum and HeLa cells or rat fibroblasts were cells well in a or 106 cells in a a was used to the cells D. B. J.P. Proc. Natl. Acad. Sci. U. S. A. Scholar). of in of was to a in This was for to of was and this was into each well in for in a the was containing serum was and cells were for In experiments a of cells was in a cells were by cells were either in for flow cytometry analysis or on for confocal microscopy analysis and for a uptake a of cells, we used V. V. A. Monsigny M. Roche A.C. 9: Scholar) the lectin C. V. J.P. Monsigny M. A. Roche A.C. J. Biol. Chem. Scholar). of rat cell expressing the human mannose receptor using has been previously M.E. Stahl P.D. Drickamer K. J. Biol. Chem. Scholar). The cell line used in this study was using the receptor in this line is as high as in the cell line as by and with an receptor antibody and uptake of E. and M. E. were by J. P. Abastado cells were in phosphate-buffered and for in in was with and a of 106 was on of were by B. N. M. Abastado J.P. M. Immunol. 2000; Scholar). The of to and was in than were well in and used of cells were for in in the presence of the fluorescein-labeled to in PBS, cells were either by for flow cytometry analysis or with a specific antibody to the membrane lectin were for a in the presence or in the of M. Roche A.C. Midoux P. Biol. Cell. 1984; 51: Scholar, P. Roche A.C. Monsigny M. Scholar), and the was by flow To for specific uptake of cells were for in the presence of as previously (7Avrameas A. McIlroy D. Hosmalin A. Autran B. Debré P. Monsigny M. Roche A.C. Midoux P. Eur. J. Immunol. 1996; 26: 394-400Google Scholar), by for in the presence of both and a fluorescein-labeled was using a flow and the were with In the of DC-SIGN, the is that of cells expressing DC-SIGN as by with an cells were using surface DC-SIGN was either by cells or cells with with by with to a antibody for flow cytometry analysis or rhodamine to an antibody for confocal microscopy The was using The and of cells with in V. V. A. Monsigny M. Roche A.C. 9: Scholar). were in containing for were on in a containing 1,4- as an G. D. J. Immunol. Scholar). was with a confocal with a and a The was to both and were with a of and with of to and DC-SIGN by Surface of the human mannose receptor of the C-type CRDs was in cells as previously Hitchen P.G. Taylor M.E. Biochem. J. Scholar, Taylor M.E. J. Biol. Chem. 2001; 276: Scholar). This of the receptor contains of the domains for of glycoconjugates and binds such ligands as well as the receptor Hitchen P.G. Taylor M.E. Biochem. J. Scholar, M.E. Drickamer K. J. Biol. Chem. Scholar). was the by affinity on of DC-SIGN of the extracellular region was by as previously (11Mitchell D.A. Fadden A.J. Drickamer K. J. Biol. Chem. 2001; 276: 28939-28945Google Scholar). was purified by affinity and To the of different glycoclusters for the mannose receptor and DC-SIGN, we to the lectins, Y. M. M. M. Y. Eur. J. Biochem. Scholar) have shown a lectin is the affinity constant is in with using in and DC-SIGN were to the with lectin of in was by a increase in the for and for DC-SIGN. The neoglycoproteins or in the or in the presence of were in the a flow of to of the was by to the for flow were experiments using a of containing or These were those that the of resonance The to determine as well as the used to are in E. Frison N. Roche A.C. Monsigny M. The of resonance was the and the affinity constant were the is the of the expressed as The for the R. J. Chem. Scholar), takes into the as well as the of the and containing and sugar of the surface of the lectin on the were into a line to the is the of the expressed as and is the association constant of the by the or have the presence of membrane lectins on the surface of human dendritic cells, but the molecules for this were not characterized (7Avrameas A. McIlroy D. Hosmalin A. Autran B. Debré P. Monsigny M. Roche A.C. Midoux P. Eur. J. Immunol. 1996; 26: 394-400Google Scholar). flow cytometry analysis and a of fluorescein-labeled neoglycoproteins sugar we that and are the neoglycoproteins efficiently internalized and of the efficiently internalized (7Avrameas A. McIlroy D. Hosmalin A. Autran B. Debré P. Monsigny M. Roche A.C. Midoux P. Eur. J. Immunol. 1996; 26: 394-400Google Scholar). we to study the uptake of such neoglycoproteins by cells expressing either the mannose receptor or DC-SIGN to than can be using dendritic cells that are to express both lectins. cell with the mannose receptor have previously been shown to efficient of M.E. Stahl P.D. Drickamer K. J. Biol. Chem. Scholar, M.E. K. Drickamer K. J. Biol. Chem. 1992; Scholar). with these rat fibroblasts expressing the mannose receptor efficiently up fluorescein-labeled on mannose was also taken up by the mannose cells, but the cells not The ligands of the mannose receptor are to be internalized into an P. Schlesinger P.H. E. Rodman J.S. Lee Y.C. Cell. for a This finding was confirmed by the to increase of cells expressing the mannose receptor that previously been for with or is to the of that is in an J. Biol. Scholar). the increase in that Flu, and internalized by the mannose receptor are to an have previously using different of cells, that neoglycoproteins sugars are specifically recognized by lectins M. Roche A.C. Midoux P. Biol. Cell. 1984; 51: Scholar). substitution and substitution to and to uptake by membrane lectins of the of M. Mayer R. Roche A.C. 2000; Scholar). with these in the of cells expressing the mannose receptor, the cell in the presence of and a with was higher with Flu, than with not were not internalized by rat fibroblasts with an not cells into dendritic cells in the presence of and (7Avrameas A. McIlroy D. Hosmalin A. Autran B. Debré P. Monsigny M. Roche A.C. Midoux P. Eur. J. Immunol. 1996; 26: 394-400Google Scholar) or into in the presence of and (13Bédouet L. Bousser M.T. Frison N. Boccaccio C. Abastado J.P. Marceau P. Mayer R. Monsigny M. Roche A.C. Biosci. Rep. 2001; 21: 839-855Google Scholar). dendritic cells and up and with high but the increase by the was This increase may be to in This may also be with the of DC-SIGN in to the mannose receptor. To on this we the uptake of the neoglycoproteins by HeLa cells or rat fibroblasts that express DC-SIGN. on specific of the HeLa cells expressed a of DC-SIGN. These cells efficiently up and sugar The uptake of was higher than that of Flu, cells that express DC-SIGN up both and Flu, but efficiently than HeLa cells expressing DC-SIGN not or HeLa cells or rat fibroblasts that not express DC-SIGN up Flu, These cells as to the specific uptake of analysis of uptake by cells expressing DC-SIGN that the uptake to the of DC-SIGN. was that was taken up by HeLa cells with DC-SIGN the low by mannose cells and The increase was with cells expressing DC-SIGN than with the mannose receptor expressing cells to This is to be to the of the lectins, including rather than to the of cells, results were with HeLa cells and rat by confocal microscopy and of the cells expressing the mannose receptor, with the cell The ligands were in small the for DC-SIGN that cells expressing DC-SIGN were to or and HeLa cells results were with rat fibroblasts expressing the the lectin used as an not microscopy analysis of uptake of by HeLa cells expressing DC-SIGN. with a DC-SIGN or a the HeLa cells on were in the presence of neoglycoproteins or cells were with and cells expressing membrane lectins were by with specific for DC-SIGN and with antibody for by with were in containing of DC-SIGN or of in the presence of cells were with to cell were and with anti DC-SIGN by are To cell surface cells were with with and The to the but not to the of DC-SIGN. The that both Flu, and were taken up by cells expressing DC-SIGN and were in close to the of Dimannoside Glycoclusters by the of glycoclusters made of disaccharides or by cells expressing membrane lectins has been previously (14Frison N. Marceau P. Roche A.C. Monsigny M. Mayer R. Biochem. J. 2002; 368: 111-119Google Scholar). up glycoclusters containing four or five with clusters taken up but not take up clusters. flow results were with fibroblasts expressing the mannose receptor. The series of clusters was first with fluorescent glycoclusters, was with to an the uptake to clusters four but uptake not increase with and for the cell for in the presence of Flu, clusters and for the was whereas the expressing the mannose receptor up clusters as efficiently as or clusters uptake was with clusters. The uptake was by in the presence of an of with for cells with and dimannoside clusters were not internalized by HeLa cells expressing DC-SIGN, DC-SIGN-expressing cells internalized with high The confocal analysis the of uptake of dimannoside was the cells in the presence of up to of Lewis neoglycoproteins are efficiently recognized and by dendritic cells as well as by cells expressing either the mannose receptor or DC-SIGN, we to clusters made of oligosaccharides containing The of and and purified as a and were into glycosynthons and were by N. L. Marceau P. C. Roche A.C. Mayer R. Monsigny M. Scholar). The of and the and and glycosynthons were to or of the fluorescein-labeled was in fibroblasts expressing the mannose receptor and in HeLa cells expressing DC-SIGN as well as in human of Lewis and by the mannose cells was than that of clusters. the dimannoside clusters were not taken up by cells expressing DC-SIGN, the Lewis clusters were taken up a by cells expressing DC-SIGN. it was the with the cell of cells expressing DC-SIGN with the Lewis clusters was than that with cells expressing the mannose receptor. Lewis clusters were internalized into as shown by the increase The was efficiently taken up than the in cell expressing mannose receptor, DC-SIGN, or Lewis clusters were also taken up by but to a than clusters The uptake of clusters by cells expressing DC-SIGN into was confirmed by confocal microscopy Surface of the neoglycoproteins for the mannose receptor and DC-SIGN were using surface plasmon of the mannose receptor of the C-type CRDs and the extracellular domain of DC-SIGN were on and were using a of to of or were and the increase in with and DC-SIGN, with a affinity than not bind to either or DC-SIGN. The of resonance was the and was the of the The were for to and for to DC-SIGN. The of neoglycoproteins to was to experiments with plasmon resonance analysis of of to lectins by not not in a new The of glycoclusters to and were on the of on lectins The depend on the of of the used as ligands and on the of the lectin on the to The clusters have a high affinity for the mannose receptor but a low affinity for DC-SIGN. The affinity with the of to and with to four the affinity constant of the containing four dimannosides and was 106 The two clusters and than that of the The affinity by of were than those by of the of In Lewis clusters a higher affinity for DC-SIGN than for the mannose receptor with and the This study that glycoclusters made of with sugars ligands for the mannose receptor and DC-SIGN. The glycoclusters are and (14Frison N. Marceau P. Roche A.C. Monsigny M. Mayer R. Biochem. J. 2002; 368: 111-119Google Scholar) and may be for to dendritic cells in human of of fluorescein-labeled glycoclusters by cells expressing either DC-SIGN or the mannose receptor and of the of different glycoclusters for the purified lectins has the ligands to use for specifically to either DC-SIGN or the mannose receptor. In the results into and trafficking of glycoprotein ligands by each of these C-type lectins. Our experiments with neoglycoproteins that both DC-SIGN and the mannose receptor are to of and The two different for these is taken up than by the mannose receptor, whereas the is for DC-SIGN. The results suggest in the these two with fucose of neoglycoproteins by the mannose receptor is well but has been of uptake mediated by DC-SIGN. In experiments with containing of mannose to by DC-SIGN (12Engering A. Geijtenbeek T.B. van Vliet S.J. Wijers M. van Liempt E. Demaurex N. Lanzavecchia A. Fransen J. Figdor C.G. Piguet V. van Kooyk Y. J. Immunol. 2002; 168: 2118-2126Google Scholar). of uptake by DC-SIGN in the study is to be to the low substitution of mannose in the containing a low of sugar bind to lectins with low the sugar on the surface is low to a or M. Mayer R. Roche A.C. 2000; Scholar). in to the efficient uptake of we that a fluorescein-labeled containing mannose was taken up very by The small in the relative of the mannose receptor and DC-SIGN to bind to is glycoclusters are Glycoclusters made of disaccharides are very ligands for the mannose receptor, but not bind to DC-SIGN, whereas glycoclusters made with Lewis are ligands for DC-SIGN. The of DC-SIGN to the dimannoside clusters it can mannose on in the of the C-type CRDs in DC-SIGN with the mannose receptor. of the dimannosides to be for to the CRDs in the DC-SIGN (11Mitchell D.A. Fadden A.J. Drickamer K. J. Biol. Chem. 2001; 276: 28939-28945Google Scholar) but for the of CRDs in the of the mannose receptor Taylor M.E. J. Biol. Chem. 2001; 276: Scholar). The dimannoside ligands for the mannose receptor are those with to a in with the of multivalent ligands M. Mayer R. Roche A.C. 2000; Scholar, Y.C. Lee Lee Y.C. Lee and Scholar), the affinity requires a of four The finding that DC-SIGN not bind to the dimannoside ligands that uptake of these ligands by previously be to the mannose receptor (14Frison N. Marceau P. Roche A.C. Monsigny M. Mayer R. Biochem. J. 2002; 368: 111-119Google Scholar). glycoclusters be used specifically to target the mannose receptor. The results also suggest that the mannose receptor and DC-SIGN ligands to different of glycoclusters is in either cells expressing the mannose receptor or cells expressing DC-SIGN, but the increase is for cells expressing the mannose receptor. glycoclusters by the mannose receptor up in very vesicles, glycoclusters taken up by DC-SIGN in is well that mannose complexes in early and that the is targeted to lysosomes the receptor to the cell surface Schlesinger P. Stahl P. Biochem. J. 1984; Scholar). In results that glycoconjugates taken up by DC-SIGN not the or not as as those taken up by the mannose receptor. of ligands taken up both by cells expressing the mannose receptor and by cells expressing DC-SIGN is in the increase in that for cells expressing DC-SIGN rather than that with cells expressing the mannose receptor. both are expressed on dendritic cells, the of DC-SIGN is in these the Lewis those containing and have high affinity for DC-SIGN, may be ligands for to this receptor in dendritic with the of the of these glycoclusters to target antigens will be the C. Boccaccio and J. P. Abastado for with the cells, G. Strecker of for with Lewis oligosaccharides and P. Marceau for in