1
|
Ishikawa T, Takizawa T, Iwaki J, Mishima T, Ui-Tei K, Takeshita T, Matsubara S, Takizawa T. Fc gamma receptor IIb participates in maternal IgG trafficking of human placental endothelial cells. Int J Mol Med 2015; 35:1273-89. [PMID: 25778799 PMCID: PMC4380207 DOI: 10.3892/ijmm.2015.2141] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/17/2015] [Indexed: 12/21/2022] Open
Abstract
The human placental transfer of maternal IgG is crucial for fetal and newborn immunity. Low-affinity immunoglobulin gamma Fc region receptor IIb2 (FCGR2B2 or FcγRIIb2) is exclusively expressed in an IgG-containing, vesicle-like organelle (the FCGR2B2 compartment) in human placental endothelial cells; thus, we hypothesized that the FCGR2B2 compartment functions as an IgG transporter. In this study, to examine this hypothesis, we performed in vitro bio-imaging analysis of IgG trafficking by FCGR2B2 compartments using human umbilical vein endothelial cells transfected with a plasmid vector containing enhanced GFP-tagged FCGR2B2 (pFCGR2B2-EGFP). FCGR2B2-EGFP signals were detected as intracellular vesicular structures similar to FCGR2B2 compartments in vivo. The internalization and transcytosis of IgG was significantly higher in the pFCGR2B2-EGFP-transfected cells than in the mock-transfected cells, and the majority of the internalized IgG was co-localized with the FCGR2B2-EGFP signals. Furthermore, we isolated FCGR2B2 compartments from the human placenta and found that the Rab family of proteins [RAS-related protein Rab family (RABs)] were associated with FCGR2B2 compartments. Among the RABs, RAB3D was expressed predominantly in placental endothelial cells. The downregulation of RAB3D by small interfering RNA (siRNA) resulted in a marked reduction in the FCGR2B2-EGFP signals at the cell periphery. Taken together, these findings suggest that FCGR2B2 compartments participate in the transcytosis of maternal IgG across the human placental endothelium and that RAB3D plays a role in regulating the intracellular dynamics of FCGR2B2 compartments.
Collapse
Affiliation(s)
- Tomoko Ishikawa
- Department of Molecular Medicine and Anatomy, Nippon Medical School, Tokyo 113-8602, Japan
| | - Takami Takizawa
- Department of Molecular Medicine and Anatomy, Nippon Medical School, Tokyo 113-8602, Japan
| | - Jun Iwaki
- Department of Molecular Medicine and Anatomy, Nippon Medical School, Tokyo 113-8602, Japan
| | - Takuya Mishima
- Department of Molecular Medicine and Anatomy, Nippon Medical School, Tokyo 113-8602, Japan
| | - Kumiko Ui-Tei
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - Toshiyuki Takeshita
- Department of Obstetrics and Gynecology, Nippon Medical School, Tokyo 113-8602, Japan
| | - Shigeki Matsubara
- Department of Obstetrics and Gynecology, Jichi Medical University, Tochigi 329-0498, Japan
| | - Toshihiro Takizawa
- Department of Molecular Medicine and Anatomy, Nippon Medical School, Tokyo 113-8602, Japan
| |
Collapse
|
2
|
Xi J, Zhang GP, Qiao SL, Guo JQ, Wang XN, Yang YY, Zhang LN, Miao XW, Zhao D, Zhi YB, Cai SJ, Luo J, Deng RG. Increased survival and reduced renal injury in MRL/lpr mice treated with a human Fcγ receptor II (CD32) peptide. Immunology 2012; 136:46-53. [PMID: 22236212 DOI: 10.1111/j.1365-2567.2012.03553.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Systemic lupus erythematosus (SLE) is a multisystem chronic inflammatory disease affecting many organs. The deposition in kidney tissue of immune complexes and their interaction with macrophages is thought to trigger the inflammatory response leading to glomerulonephritis. It has been demonstrated that inhibition of this interaction in murine models can alleviate the disease. Six synthetic peptides were derived from the membrane-proximal extracellular domain (EC2) of human Fcγ receptor II (huFcγRII). Of these, one peptide, huRII6, was shown to be a potent competitive inhibitor of IgG binding to recombinant FcγRII in vitro. To examine the possible therapeutic impact of huRII6 in vivo, this peptide, or a control, was given by subcutaneous injection to female MRL/lpr mice from weeks 7 to 36, resulting in an enhanced survival rate compared with control-treated animals and a reduction of proteinuria. Histopathological examination of the kidneys showed a reduction in deposition of immune complexes and preservation of structure. Such a functional peptide should prove useful for examining the role of IgG-FcγR interactions in experimental models of disease and may provide for the development of FcR-targeting drugs to treat autoimmune disorders.
Collapse
Affiliation(s)
- Jun Xi
- School of Food Science and Technology, Henan University of Technology, Zhengzhou, China.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
3
|
Machino Y, Ohta H, Suzuki E, Higurashi S, Tezuka T, Nagashima H, Kohroki J, Masuho Y. Effect of immunoglobulin G (IgG) interchain disulfide bond cleavage on efficacy of intravenous immunoglobulin for immune thrombocytopenic purpura (ITP). Clin Exp Immunol 2010; 162:415-24. [PMID: 21029072 DOI: 10.1111/j.1365-2249.2010.04255.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Intravenous immunoglobulin (IVIG) has been used widely to treat immune thrombocytopenic purpura (ITP), but the mechanisms of its action remain unclear. We investigated the affinity for Fcγ receptors (FcγRs) and the thrombocytopenia-ameliorating effect of S-sulfonated gammaglobulin (SGG) and S-alkylated gammaglobulin (AGG), in comparison with unmodified gammaglobulin (GG), in a mouse ITP model. Cleavage of immunoglobulin (Ig)G interchain disulfide bonds by either S-sulfonation or S-alkylation did not decrease the affinity for FcγRIIA (CD32A) and FcγRIIB (CD32B), but did decrease the affinity for FcγRIA (CD64A) and FcγRIIIA (CD16A), presumably because of changes in H-chain configuration. The interchain disulfide bond cleavage decreased the affinity much more for mouse FcγRIV than for mouse FcγRIIB. The ability of AGG to ameliorate ITP was greatly diminished, while SGG, whose disulfide bonds are reconstituted in vivo, was as effective as GG. These results suggest that the interchain disulfide bonds are important for therapeutic effect. It is also suggested that the interaction of IVIG with the inhibitory receptor FcγRIIB is insufficient for effective amelioration of ITP and that, at least in this model, direct binding of IVIG to FcγRIIIA is also required.
Collapse
Affiliation(s)
- Y Machino
- Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan
| | | | | | | | | | | | | | | |
Collapse
|
4
|
Xi J, Zhang LN, Hu GP, Wang L, Qiao SL, Guo JQ, Lu QY, Zhang GP, Yang YY. Identification of a linear epitope for Fc-binding in the mouse FcγRIII. Peptides 2010; 31:1684-8. [PMID: 20566342 DOI: 10.1016/j.peptides.2010.05.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 05/31/2010] [Accepted: 05/31/2010] [Indexed: 11/26/2022]
Abstract
Fc receptors are transmembrane proteins, found on the surfaces of immune cells, that aid in the removal of foreign pathogens by binding to antibody-coated targets via the Fc regions of the antibodies. To identify sites on mouse FcgammaRIII (moFcgammaRIII) alpha-chain that bind to the Fc region, peptides derived from the proximal extracellular domain (EC2) of moFcgammaRIII alpha-chain corresponding to the homologous region of human FcgammaRIIIB alpha-chain were synthesized. Binding of mouse IgG to the different peptides was tested by Dot-blot assay. The effective peptide (119)SFFHNEKSVRYH(130) located in the putative C-C' loop of the EC2 domain was found to bind mouse IgG specifically with an affinity of approximately 5.58 x 10(-5) M and inhibit the binding of mouse IgG to the receptor. Such a functional peptide should be very useful for further understanding the IgG-FcgammaR interaction and development of FcR-targeting drugs.
Collapse
Affiliation(s)
- Jun Xi
- School of Food Science and Technology, Henan University of Technology, Zhengzhou 450052, China
| | | | | | | | | | | | | | | | | |
Collapse
|
5
|
An Z, Forrest G, Moore R, Cukan M, Haytko P, Huang L, Vitelli S, Zhao JZ, Lu P, Hua J, Gibson CR, Harvey BR, Montgomery D, Zaller D, Wang F, Strohl W. IgG2m4, an engineered antibody isotype with reduced Fc function. MAbs 2010; 1:572-9. [PMID: 20073128 DOI: 10.4161/mabs.1.6.10185] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The Fc region of an antibody mediates effector functions such as antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC), and plays a key role in the in vivo half-life of an antibody. In designing antibody therapeutics, it is sometimes desirable that the antibody has altered Fc-mediated properties. In the case of a "benign blocker" antibody, it is often desirable to diminish or abolish the ADCC and CDC functions while retaining its PK profile. Here, we report a novel engineered IgG isotype, IgG2m4, with reduced Fc functionality. IgG2m4 is based on the IgG2 isotype with four key amino acid residue changes derived from IgG4 (H268Q, V309L, A330S and P331S). An IgG2m4 antibody has an overall reduction in complement and Fc gamma receptor binding in in vitro binding analyses while maintaining the normal in vivo serum half-life in rhesus.
Collapse
Affiliation(s)
- Zhiqiang An
- Department of Biologics Research, West Point, PA, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Nakamura A, Kubo T, Takai T. Fc receptor targeting in the treatment of allergy, autoimmune diseases and cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 640:220-33. [PMID: 19065795 DOI: 10.1007/978-0-387-09789-3_17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Fc receptors (FcRs) play an important role in the maintenance of an adequate activation threshold of various cells in antibody-mediated immune responses. Analyses of murine models show that the inhibitory FcR, FcyRIIB plays a pivotal role in the suppression of antibody-mediated allergy and autoimmunity. On the other hand, the activating-type FcRs are essential for the development of these diseases, suggesting that regulation of inhibitory or activating FcR is an ideal target for a therapeutic agent. Recent experimental or clinical studies also indicate that FcRs function as key receptors in the treatment with monoclonal antibodies (mAbs) therapy. This review summarizes FcR functions and highlights possible FcR-targeting therapies including mAb therapies for allergy, autoimmune diseases and cancer.
Collapse
Affiliation(s)
- Akira Nakamura
- Department of Experimental Immunology and CREST program of Japan Science and Technology Agency, Institute of Development, Aging and Cancer, Tohoku University, Seiryo 4-1, Sendai 980-8575, Japan.
| | | | | |
Collapse
|
7
|
Berntzen G, Andersen JT, Ustgård K, Michaelsen TE, Mousavi SA, Qian JD, Kristiansen PE, Lauvrak V, Sandlie I. Identification of a high affinity FcgammaRIIA-binding peptide that distinguishes FcgammaRIIA from FcgammaRIIB and exploits FcgammaRIIA-mediated phagocytosis and degradation. J Biol Chem 2008; 284:1126-35. [PMID: 18957413 DOI: 10.1074/jbc.m803584200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
FcgammaRIIA is a key activating receptor linking immune complex formation with cellular effector functions. FcgammaRIIA has 93% identity with an inhibitory receptor, FcgammaRIIB, which negatively regulates FcgammaRIIA. FcgammaRIIA is important in the therapeutic action of several monoclonal antibodies. Binding molecules that discriminate FcgammaRIIA from FcgammaRIIB may optimize receptor activity and serve as a lead for development of therapeutics with FcgammaRIIA as a key target. Here we report the use of phage display libraries to select short peptides with distinct FcgammaRIIA binding properties. An 11-mer peptide (WAWVWLTETAV) was characterized that bound FcgammaRIIA with a K(d) of 500 nm. It mediated cell internalization and degradation of a model antigen. The peptide-binding site on FcgammaRIIA was shown to involve Phe(163) and the IgG binding amino acids Trp(90) and Trp(113). It is thus overlapping but not identical to that of IgG. Neither activating receptors FcgammaRI and FcgammaRIII, nor FcgammaRIIB, all of which lack Phe(163), bound the peptide.
Collapse
Affiliation(s)
- Gøril Berntzen
- Department of Molecular Biosciences, University of Oslo, Oslo, Norway
| | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Kavai M, Szegedi G. Immune complex clearance by monocytes and macrophages in systemic lupus erythematosus. Autoimmun Rev 2007; 6:497-502. [PMID: 17643939 DOI: 10.1016/j.autrev.2007.01.017] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2007] [Accepted: 01/23/2007] [Indexed: 11/28/2022]
Abstract
During the last 30 years more than 700 patients with systemic lupus erythematosus (SLE) have been treated in our department with their data analyzed. Here we focus on circulating immune complex (CIC) and its clearance. We demonstrated, microscopically, that the uptake of IgG sensitized erythrocytes (EA), via monocytes (Mo) of SLE patients, was elevated and correlated with the high CIC content. The in Vivo clearance of sensitized autolog E, and the in vitro degradation rate of soluble IC by Mo of SLE patients were decreased. This discrepancy could be explained by the molecular heterogeneity of FcgammaR being recognized lately. The high FcgammaRI expression and the low FcgammaRII and FcgammaRIII expression were detected by monoclonal antibodies (mAb) on Mo in SLE. The EA bound mostly to FcgammaRI, FcgammaRII and FcgammaRIII have a role in phagocytosis. The decreased receptor expression and function correlated with the disease activity and renal involvement. The shedding of receptors may cause a decrease on Mo surface, with the soluble FcRII and FcgammaRIII levels being elevated in serum of SLE patients. The mannose binding receptors, which play a role in the phagocytosis of apoptotic cells in SLE, were also decreased on Mo of SLE patients.
Collapse
Affiliation(s)
- Maria Kavai
- 3rd Department of Medicine, Medical and Health Science Center, University of Debrece, Debrecen, Hungary.
| | | |
Collapse
|
9
|
Cendron AC, Wines BD, Brownlee RTC, Ramsland PA, Pietersz GA, Hogarth PM. An FcgammaRIIa-binding peptide that mimics the interaction between FcgammaRIIa and IgG. Mol Immunol 2007; 45:307-19. [PMID: 17673295 DOI: 10.1016/j.molimm.2007.06.152] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 06/13/2007] [Accepted: 06/17/2007] [Indexed: 10/23/2022]
Abstract
A disulphide-constrained peptide that binds to the low affinity Fc receptor, FcgammaRIIa (CD32) has been identified and its structure solved by NMR. Linear (7-mer and 12-mer) and disulphide-constrained (7-mer) phage display peptide libraries were panned on recombinant soluble FcgammaRIIa genetically fused to HSA (HSA-FcgammaRIIa). Peptides were isolated only from the constrained peptide library and these contained the consensus sequence, CWPGWxxC. Phage clones displaying variants of the peptide consensus sequence bound to FcgammaRIIa and the strongest binding clone C7C1 (CWPGWDLNC) competed with IgG for binding to FcgammaRIIa and was inhibited from binding to FcgammaRIIa by the FcgammaRIIa-blocking antibody, IV.3, suggesting that C7C1 and IgG share related binding sites on FcgammaRIIa. A synthetic disulphide-constrained peptide, pep-C7C1 bound to FcgammaRIIa by biosensor analysis, albeit with low affinity (KD approximately 100microM). It was significant that the FcgammaRIIa consensus peptide sequence contained a Proline (Pro3), which when substituted with alanine abrogated FcgammaRIIa binding, consistent with Pro3 contributing to receptor binding. Upon binding of IgG and IgE to their respective Fc receptors (FcgammaRs and FcepsilonRI) Pro329 in the Fc makes a critical interaction with two highly conserved Trp residues (Trp90 and Trp113) of the FcRs. The NMR structure of pep-C7C1 revealed a stabilizing type II beta-turn between Trp2 and Trp5, with Pro3 solvent exposed. Modelling of the pep-C7C1 structure in complex with FcgammaRIIa suggests that Pro3 of C7C1 binds to FcgammaRIIa by inserting between Trp90 and Trp113 of FcgammaRIIa thereby mimicking the molecular interaction made between FcgammaRIIa and IgG.
Collapse
Affiliation(s)
- Angela C Cendron
- Burnet Institute, Austin Campus, Studley Road, Heidelberg, Vic. 3084, Australia
| | | | | | | | | | | |
Collapse
|
10
|
Csipo I, Barath S, Kiss E, Szucs G, Szegedi G, Kavai M. Determination of ligand binding capacity of soluble Fc gamma RII and Fc gamma RIII in sera of patients with SLE. Autoimmunity 2007; 40:165-8. [PMID: 17453714 DOI: 10.1080/08916930601119344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
BACKGROUND Soluble, human low affinity Fcgamma receptors, such as sFcgammaRII and sFcgammaRIII, are known to play a pathologic role in different diseases. Sandwich ELISAs had previously been applied for the specific detection and determination of these soluble receptors. In these ELISAs, commercial monoclonal antibodies (Ab) were used as capture antibodies with monoclonal or polyclonal antibodies serving as detector Abs. Increased levels of cell-free FcgammaRIII have been detected in patients with lupus but the functions and levels of sFcgammaRII have not been fully characterized yet. OBJECTIVES The aim of this work was to determine the ligand binding capacities and levels of soluble FcgammaRII and FcgammaRIII in sera of patients with systemic lupus erythematosus (SLE). Moreover, correlation between the levels of sFcgammaRII and sFcgammaRIII and the clinical activity of the disease were investigated. METHODS Sera of 47 patients with SLE, and 51 healthy subjects were analyzed. In the newly developed indirect sandwich ELISAs commercial monoclonal anti-FcgammaRs are used as capture antibodies, and the ligand of FcgammaRII and FcgammaRIII, an artificial immune complex (IC), serves as a detection component replacing the second antibodies used in previous methods. RESULTS The ligand binding capacity of both soluble FcgammaRII and sFcgammaRIII were elevated in the sera of SLE patients compared to control samples. This increase was significant in patients with the active disease (n = 30; p < 0.01). It was also revealed that a substantial part of the soluble Fcgamma receptors in these patients was bound in vivo to circulating IC. CONCLUSION These newly developed ELISAs are probably more phisiologically relevant than other previous assays because they detect the circulating receptors on the basis their in vitro ligan binding capacities. Therefore this method can separately measure the levels of the soluble, free FcgammaRs and those bound circulating IC in vivo.
Collapse
Affiliation(s)
- Istvan Csipo
- 3rd Department of Internal Medicine, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary
| | | | | | | | | | | |
Collapse
|
11
|
Zhang G, Guo J, Zhou J, Wang X, Li Q, Yang Y, Shen H, Zhao D, Zhang H, Xi J, Wang L, Qiao S, Jin X. Identification of the linear epitope for Fc-binding on the bovine IgG2 Fc receptor (boFcgamma2R) using synthetic peptides. FEBS Lett 2006; 580:1383-90. [PMID: 16457820 DOI: 10.1016/j.febslet.2006.01.060] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Revised: 01/14/2006] [Accepted: 01/17/2006] [Indexed: 01/25/2023]
Abstract
To identify the linear epitope for Fc-binding on the bovine IgG2 Fc receptor (boFcgamma2R), peptides derived from the membrane-distal extracellular domain (EC1) of boFcgamma2R corresponding to the homologous region of human FcalphaRI were synthesized. Binding of bovine IgG2 to the different peptides was tested by Dot-blot assay, and the peptide showing maximal binding was further modified by truncation and mutation. The minimum effective peptide 82FIGV85 located in the putative F-G loop of the EC1 domain was found to bind bovine IgG2 specifically and inhibit the binding of bovine IgG2 to the receptor. The Phe82, Ile83 and Val85 residues within the linear epitope were shown to be critical for IgG2-binding. Such functional epitope peptide should be very useful for understanding the IgG-Fcgamma interaction and development of FcR-targeting drugs.
Collapse
Affiliation(s)
- Gaiping Zhang
- Henan Key Laboratory for Animal Immunology, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Berntzen G, Brekke OH, Mousavi SA, Andersen JT, Michaelsen TE, Berg T, Sandlie I, Lauvrak V. Characterization of an FcgammaRI-binding peptide selected by phage display. Protein Eng Des Sel 2006; 19:121-8. [PMID: 16423844 DOI: 10.1093/protein/gzj011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The high-affinity IgG receptor, Fcgamma receptor I (FcgammaRI), is expressed exclusively on myeloid cells, and there is a great interest in the targeting of vaccine antigens to FcgammaRI using anti-human FcgammaRI antibodies or fragments derived from such molecules. In order to reduce the size and complexity of the targeting reagent, we have searched for FcgammaRI binding peptides in peptide libraries displayed on phage. The human monocytic cell line U937 was used as target. Phages that displayed the consensus peptide CLRSGXGC were selected and revealed increased binding to IFN-gamma stimulated versus non-stimulated U937 cells as well as to FcgammaRI transfected versus non-transfected IIA1.6 cells. Furthermore, they bound the extracellular domains of soluble FcgammaRI, but neither FcgammaRIIA, FcgammaRIIB nor FcgammaRIIIB. Binding was inhibited by a synthetic version of the peptide, whereas neither human IgG nor the FcgammaRI-specific monoclonal antibodies (mAb) mAb22 and 32.2 interfered. Flow-cytometry analysis and internalization studies showed that a synthetic biotin-conjugated peptide ADGACLRSGRGCGAAK-bio was able to target U937 cells and FcgammaRI transfected IIA1.6 cells, and further to promote internalization and vesicular degradation of streptavidin coupled to 1 microm magnetic beads. These peptides may have potential as FcgammaRI targeting reagents.
Collapse
Affiliation(s)
- G Berntzen
- Department of Molecular Biosciences, University of Oslo, Norway
| | | | | | | | | | | | | | | |
Collapse
|