Monoclonal IgG Specific for the CD44 Antigen Mimics the Action of IVIg in the Amelioration of ITP.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2170-2170
Author(s):  
Seng Song ◽  
Andrew R. Crow ◽  
Vinayakumar Siragam ◽  
John Freedman ◽  
Alan Lazarus
Keyword(s):  
Monoclonal Antibody ◽  
Cancer Progression ◽  
Surface Protein ◽  
Mechanisms Of Action ◽  
Fc Receptor ◽  
Cell Surface Protein ◽  
Cell Homing ◽  
Splenic Macrophages ◽  
Splenic Cells

Abstract Previous work in our laboratory has shown that both IVIg and “anti-D like” erythrocyte-reactive antibodies ameliorate immune thrombocytopenia (ITP) in a murine model. However, they appear to function through different mechanisms: IVIg is dependent upon the inhibitory Fc receptor, FcγRIIB in the amelioration of ITP, but the anti-erythrocyte antibodies function independently of FcγRIIB expression. We have also demonstrated that anti-erythrocyte antibodies down-modulate the expression of the activating Fc receptor, FcγRIIIA in splenic macrophages during the amelioration of ITP. A monoclonal antibody to CD44, cell surface protein involved in cell homing, cancer progression and inflammation, can also ameliorate murine ITP. Elucidation of the mechanisms of action of anti-CD44 antibodies in the amelioration of ITP would be critical to the successful application of this potential therapy. In this report, two monoclonal antibodies against CD44, KM114 and IM7 were studied in C57BL/6 and FcγRIIB−/− mice to assess their therapeutic activity in treating ITP. Both KM114 and IM7 bound well to splenic cells from all mice tested. Neither KM114 nor IM7 demonstrated any in vitro anti-idiotypic activity which could neutralize the binding of the thrombocytopenia-inducing anti-platelet antibody. At the dose that protected against thrombocytopenia, KM114 did not mediate RES blockade. In contrast, IM7, which did not at all protect against thrombocytopenia, blocked RES. Since FcγRIIB has been documented to play a key role in the function of IVIg in the amelioration of ITP, we questioned the significance of it in the function of KM114. Surprisingly, KM114 was not able to ameliorate ITP in mice genetically deficient in FcγRIIB. These results suggest that, like IVIg, monoclonal antibody against CD44 mediates amelioration of murine thrombocytopenia in a manner dependent upon the inhibitory FcγRIIB rather than via RES blockade.

scholarly journals A Histoplasma capsulatum-Specific IgG1 Isotype Monoclonal Antibody, H1C, to a 70-Kilodalton Cell Surface Protein Is Not Protective in Murine Histoplasmosis

2010 ◽  
Vol 17 (7) ◽  
pp. 1155-1158 ◽  
Author(s):  
Livia Cristina Liporagi Lopes ◽  
Allan J. Guimarães ◽  
Mariana Duarte de Cerqueira ◽  
Beatriz L. Gómez ◽  
Joshua D. Nosanchuk
Keyword(s):  
Nitric Oxide ◽  
Monoclonal Antibody ◽  
Monoclonal Antibodies ◽  
Histoplasma Capsulatum ◽  
Fungal Growth ◽  
Surface Protein ◽  
Cell Surface Protein ◽  
Fungal Burden ◽  
Nitric Oxide Release ◽  
Igg1 Isotype

ABSTRACT Monoclonal antibodies to Histoplasma capsulatum can modify pathogenesis. We now show that monoclonal antibody H1C to a 70-kDa antigen increases intracellular fungal growth and reduces macrophage nitric oxide release but has no effect on fungal burden or survival in murine infection. This further demonstrates the complexities of host-pathogen interactions.

scholarly journals Major Surface Protein 2 of Anaplasma phagocytophilum Facilitates Adherence to Granulocytes

2003 ◽  
Vol 71 (7) ◽  
pp. 4018-4025 ◽  
Author(s):  
Jinho Park ◽  
Kyoung Seong Choi ◽  
J. Stephen Dumler
Keyword(s):  
Monoclonal Antibody ◽  
Bacterial Adhesion ◽  
Anaplasma Phagocytophilum ◽  
Human Peripheral Blood ◽  
Myeloid Cells ◽  
Surface Protein ◽  
Mammalian Host ◽  
Blood Neutrophils ◽  
Major Surface

ABSTRACT Anaplasma phagocytophilum is an obligate intracellular bacterium that infects myeloid cells in the mammalian host. Msp2 (p44) is the major immunodominant outer-membrane protein of these bacteria. We hypothesized that Msp2 acts as an adhesin for A. phagocytophilum entry into granulocytes. This potential role was investigated by blocking binding with Msp2 monoclonal antibodies and by antagonizing binding and propagation with recombinant Msp2 (rMsp2) in vitro. With HL-60 cells, fresh human peripheral blood neutrophils, and a cell line devoid of the fucosylated platelet selectin glycoprotein ligand 1 (PSGL-1) receptor for A. phagocytophilum or one that was transfected to express this ligand, Msp2 monoclonal antibody and rMsp2 used as the antagonist caused concentration-dependent reductions in bacterial adhesion (P < 0.007 and P < 0.02, respectively) and propagation (P < 0.05 and P < 0.001), although inhibition of adhesion or propagation was moderate and incomplete. Likewise, rMsp2 bound to surfaces of the transfected cell at a level similar to that of extracellular A. phagocytophilum and significantly (P < 0.05) beyond that of nontransfected cells. Moreover, a dose-dependent reduction (P < 0.019) in PSGL-1 monoclonal antibody binding to HL-60 cells was elicited with rMsp2. We conclude that Msp2s of A. phagocytophilum are involved in bacterial adhesion to ligands on host myeloid cells before intracellular infection.

scholarly journals Homologue of Macrophage-Activating Lipoprotein in Mycoplasmagallisepticum Is Not Essential for Growth and Pathogenicity in Tracheal Organ Cultures

2003 ◽  
Vol 185 (8) ◽  
pp. 2538-2547 ◽  
Author(s):  
Philip F. Markham ◽  
Anna Kanci ◽  
György Czifra ◽  
Bo Sundquist ◽  
Peter Hains ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Tetracycline Resistance ◽  
Surface Protein ◽  
Enzyme Linked Immunosorbent Assay ◽  
Homologous Gene ◽  
Organ Cultures ◽  
Western Blots ◽  
Wide Range ◽  
The Difference

ABSTRACT While the genomes of a number of Mycoplasma species have been fully determined, there has been limited characterization of which genes are essential. The surface protein (p47) identified by monoclonal antibody B3 is the basis for an enzyme-linked immunosorbent assay for serological detection of Mycoplasma gallisepticum infection and appears to be constitutively expressed. Its gene was cloned, and the DNA sequence was determined. Subsequent analysis of the p47 amino acid sequence and searches of DNA databases found homologous gene sequences in the genomes of M. pneumoniae and M. genitalium and identity with a gene family in Ureaplasma urealyticum and genes in M. agalactiae and M. fermentans. The proteins encoded by these genes were found to belong to a family of basic membrane proteins (BMP) that are found in a wide range of bacteria, including a number of pathogens. Several of the BMP family members, including p47, contain selective lipoprotein-associated motifs that are found in macrophage-activating lipoprotein 404 of M. fermentans and lipoprotein P48 of M. agalactiae. The p47 gene was predicted to encode a 59-kDa peptide, but affinity-purified p47 had a molecular mass of approximately 47 kDa, as determined by polyacrylamide gel analysis. Analysis of native and recombinant p47 by mass peptide fingerprinting revealed the absence of the carboxyl end of the protein encoded by the p47 gene in native p47, which would account for the difference seen in the predicted and measured molecular weights and indicated posttranslational cleavage of the lipoprotein at its carboxyl end. A DNA construct containing the p47 gene interrupted by the gene encoding tetracycline resistance was used to transform M. gallisepticum cells. A tetracycline-resistant mycoplasma clone, P2, contained the construct inserted within the genomic p47 gene, with crossovers occurring between 73 bp upstream and 304 bp downstream of the inserted tetracycline resistance gene. The absence of p47 protein in clone P2 was determined by the lack of reactivity with rabbit anti-p47 sera or monoclonal antibody B3 in Western blots of whole-cell proteins. There was no difference between the p47− mutant and wild-type M. gallisepticum in pathogenicity in chicken tracheal organ cultures. Thus, p47, although homologous to genes that occur in many prokaryotes, is not essential for growth in vitro or for attachment and the initial stages of pathogenesis in chickens.

scholarly journals A high-molecular-mass cell-surface protein from Lactobacillus reuteri 1063 adheres to mucus components The GenBank accession number for the sequence reported in this paper is AF120104.

Microbiology ◽  
2002 ◽  
Vol 148 (2) ◽  
pp. 433-442 ◽  
Author(s):  
Stefan Roos ◽  
Hans Jonsson
Keyword(s):  
Cell Surface ◽  
Lactobacillus Reuteri ◽  
Surface Protein ◽  
Surface Proteins ◽  
Cell Surface Protein ◽  
Intestinal Mucus ◽  
A Cell ◽  
Molecular Masses ◽  
Ph Range

A gene from Lactobacillus reuteri 1063 encoding a cell-surface protein, designated Mub, that adheres to mucus components in vitro has been cloned and sequenced. The deduced amino acid sequence of Mub (358 kDa) shows the presence of 14 approximately 200 aa repeats and features typical for other cell-surface proteins of Gram-positive bacteria. Fusion proteins consisting of different repeats of Mub and the maltose-binding protein (MBP) were produced. These proteins adhered to pig mucus components, with molecular masses ranging from <0·1 to >2 MDa, to pig gastric mucin and to hen intestinal mucus. The binding of Mub to mucus components occurred in the pH range 3–7·4, with maximum binding at pH 4–5 and could be partly inhibited by the glycoprotein fetuin. Affinity-purified antibodies against recombinant Mub were used in immunofluorescence microscopy to demonstrate the presence of Mub on the cell surface of strain 1063. By using the antibodies in a Western blot analysis, Mub could also be detected in the growth medium. The results implicate Mub as a cell-surface protein that is involved in Lactobacillus interactions with mucin and in colonization of the digestive tract.

scholarly journals Function of Candida albicans Adhesin Hwp1 in Biofilm Formation

2006 ◽  
Vol 5 (10) ◽  
pp. 1604-1610 ◽  
Author(s):  
Clarissa J. Nobile ◽  
Jeniel E. Nett ◽  
David R. Andes ◽  
Aaron P. Mitchell
Keyword(s):  
Candida Albicans ◽  
Cell Surface ◽  
Biofilm Formation ◽  
Tight Binding ◽  
Surface Protein ◽  
Venous Catheter ◽  
Cell Surface Protein ◽  
Additional Support

ABSTRACT Hwp1 is a well-characterized Candida albicans cell surface protein, expressed only on hyphae, that mediates tight binding to oral epithelial cells. Prior studies indicate that HWP1 expression is dependent upon Bcr1, a key regulator of biofilm formation. Here we test the hypothesis that Hwp1 is required for biofilm formation. In an in vitro model, the hwp1/hwp1 mutant produces a thin biofilm that lacks much of the hyphal mass found in the hwp1/HWP1 reconstituted strain. In a biofilm cell retention assay, we find that the hwp1/hwp1 mutant is defective in retention of nonadherent bcr1/bcr1 mutant cells. In an in vivo rat venous catheter model, the hwp1/hwp1 mutant has a severe biofilm defect, yielding only yeast microcolonies in the catheter lumen. These properties of the hwp1/hwp1 mutant are consistent with its role as a hypha-specific adhesin and indicate that it is required for normal biofilm formation. Overexpression of HWP1 in a bcr1/bcr1 mutant background improves adherence in the in vivo catheter model. This finding provides additional support for the model that Hwp1 is critical for biofilm adhesion. Hwp1 is the first cell surface protein known to be required for C. albicans biofilm formation in vivo and is thus an excellent therapeutic target.

scholarly journals Localization of CD9 in pig oocytes and its effects on sperm–egg interaction

Reproduction ◽  
2004 ◽  
Vol 127 (2) ◽  
pp. 151-157 ◽  
Author(s):  
Yong-Hai Li ◽  
Yi Hou ◽  
Wei Ma ◽  
Jin-Xiang Yuan ◽  
Dong Zhang ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Surface Protein ◽  
Early Growth ◽  
Meiotic Maturation ◽  
Cell Surface Protein ◽  
Cellular Processes ◽  
Sperm Binding ◽  
Sperm Penetration ◽  
A Cell

CD9 is a cell surface protein that participates in many cellular processes, such as cell adhesion. Fertilization involves sperm and oocyte interactions including sperm binding to oocytes and sperm–oocyte fusion. Thus CD9 may play an essential role during fertilization in mammals. The present study was conducted to examine whether CD9 is present in porcine gametes and whether it participates in the regulation of sperm–oocyte interactions. The presence of CD9 in ovarian tissues, oocytes and spermatozoa was examined by immunohistochemistry, immunofluorescence and immunoblotting. Sperm binding and penetration of oocytes treated with CD9 antibody were examined by in vitro fertilization. The results showed that CD9 was present on the plasma membrane of oocytes at different developmental stages. A 24 kDa protein was found in oocytes during in vitro maturation by immunoblotting and its quantity was significantly (P < 0.001) increased as oocytes underwent maturation and reached the highest level after the oocytes had been cultured for 44 h. No positive CD9 staining was found in the spermatozoa. Both sperm binding to ooplasma and sperm penetration into oocytes were significantly (P < 0.01) reduced in anti-CD9 antibody-treated oocytes (1.2 ± 0.2 per oocyte and 16.6% respectively) as compared with oocytes in the controls (2.5 ± 0.4 per oocyte and 70.3% respectively). These results indicated that CD9 is expressed in pig oocytes during early growth and meiotic maturation and that it participates in sperm–oocyte interactions during fertilization.

scholarly journals Prophylaxis and Therapy of Inhalational Anthrax by a Novel Monoclonal Antibody to Protective Antigen That Mimics Vaccine-Induced Immunity

2006 ◽  
Vol 74 (10) ◽  
pp. 5840-5847 ◽  
Author(s):  
Laura Vitale ◽  
Diann Blanset ◽  
Israel Lowy ◽  
Thomas O'Neill ◽  
Joel Goldstein ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Protective Antigen ◽  
Fc Receptor ◽  
Anthrax Toxin ◽  
Functional Assay ◽  
Human Mabs ◽  
Anthrax Spores ◽  
Anthrax Vaccines

ABSTRACT The neutralizing antibody response to the protective antigen (PA) component of anthrax toxin elicited by approved anthrax vaccines is an accepted correlate for vaccine-mediated protection against anthrax. We reasoned that a human anti-PA monoclonal antibody (MAb) selected on the basis of superior toxin neutralization activity might provide potent protection against anthrax. The fully human MAb (also referred to as MDX-1303 or Valortim) was chosen from a large panel of anti-PA human MAbs generated using transgenic mice immunized with recombinant PA solely on the basis of in vitro anthrax toxin neutralization. This MAb was effective in prophylactic and postsymptomatic treatment of rabbits exposed to aerosolized anthrax spores, and a single intramuscular injection of 1 mg/kg of body weight fully protected cynomolgus monkeys challenged with aerosolized anthrax spores. Importantly, MAb 1303 defines a novel neutralizing epitope that requires Fc receptor engagement for maximal activity. F(ab′)2 fragments of MAb 1303, which retain equivalent affinity for PA, are 10- to 100-fold less potent in neutralizing anthrax toxin in vitro. Addition of Fc receptor-blocking antibodies also greatly reduced the activity of MAb 1303. Moreover, we found that the neutralizing activity of mouse, rabbit, and human antisera elicited by PA vaccines was effectively abrogated by blocking Fc receptors. Selection of an anti-PA MAb by using a functional assay that is a surrogate for protection has resulted in the identification of a fully human MAb with potent activity in vivo and uncovered a previously unrecognized mechanism of antibody-mediated toxin neutralization that is important for currently used anthrax vaccines.

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