Soluble FcR Block Suppressor T Cell Activity at Low Concentrationin VitroAllowing Isotype-Specific Antibody Production

Simpson, Scott D.; Snider, Denis P.; Zettel, Lenore; Kiyono, Hiroshi; Unkeless, Jay C.; Ernst, Peter B.

doi:10.1006/cimm.1996.0015

Cited by 7 publications

(2 citation statements)

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“…Our experiments strongly suggest that the FcR activity is a parasite product. Indeed, mammalian membrane FcR are easily released under soluble form into the supernatant of cells and blood (Selvaraj et al 1988, Sautès et al 1991, Simpson et al 1996. They are also found in the host's circulation (Ulvestad, Matre & Tonder 1988, Araujo Jorge Volume 20, Number 1, January 1998 Fc receptor activity on the T. gondii tachyzoite et al 1993).…”

Section: Discussionmentioning

confidence: 99%

Identification and characterization of a Fc Receptor activity on the Toxoplasma gondii tachyzoite

VERCAMMEN¹,

BOUHDIDI²,

MESSAOUD³

et al. 1998

Parasite Immunol

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The Immunoglobulin (Ig) binding capacity of Toxoplasma gondii tachyzoites was investigated using fluorescence flowcytometry analysis. Polyclonal mouse, human and rat immunoglobulins without specific anti-Toxoplasma activity bound to parasites in a concentration-dependent manner, saturating them at circulating serum concentrations. The immunoglobulin class and subclass specificity of binding was investigated using irrelevant monoclonal antibodies. IgM, IgA and IgG reacted with the parasite membrane. The attachment of mouse IgM to the parasite surface was hampered by mouse IgG1, IgG2a, IgG2b and IgG3. The binding of mouse IgG was proportionally reduced with increasing concentrations of mouse monoclonal IgM. The binding of murine immunoglobulin was diminished when in presence of human IgG. Purified Fc-but not Fab portions of immunoglobulins, fixed to parasites. Using labelled calibrated beads, the Ig binding capacity of parasites was estimated to be 6900 Ϯ 500 sites per tachyzoite. The Kd of the T. gondii Fc Receptor (FcR) activity was determined at 1·4 Ϯ 0·1 mM (mean Ϯ SEM). Such FcR activity was reduced by phospholipase C, trypsin and pronase treatment of the parasites. These data show a low affinity FcR activity on T. gondii tachyzoites which recognizes Ig of different species and isotypes and is likely supported by a glycosyl-phosphatidylinositol (GPI)-anchored surface protein of the parasite.

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Section: Discussionmentioning

confidence: 99%

Identification and characterization of a Fc Receptor activity on the Toxoplasma gondii tachyzoite

VERCAMMEN¹,

BOUHDIDI²,

MESSAOUD³

et al. 1998

Parasite Immunol

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“…Thus, efforts have been made to optimize MoAbs by isolating switch variants using cellular [ 1 1,121 or molecular [13,14] techniques. For instance, the comparison of human chimeric IgGl, IgG2, IgG3, and IgG4 antibody effector functions showed that the chimeric IgGl was much more effective than all the other IgG subclasses in mediating ADCC using human FcyRIf effector cells, as well as in complement-dependent hemolysis 1141 Similarly, the functional analysis of mouse isotype-switch variants, isolated from an IgG 1 -secreting hybridoma, showed that tumor lysis was optimum when the IgG2a switch variant was used, while IgGl and IgG2b were virtually inactive [17]. In fact, mouse IgG2a and human IgG1 are of particular interest in ADCC, since they strongly bind FcyRI which is an excellent cytotoxic trigger molecule, notably when expressed on interferon y (1FNy)-treated cells [5].…”

Section: Introductionmentioning

confidence: 99%

Fc Receptors as Targets for Immunotherapy

Rouard

Tamasdan

Moncuit

et al. 1997

International Reviews of Immunology

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Human membrane and soluble Fc epsilon receptors (Fc epsilon RI, Fc epsilon RII/CD23) and Fc gamma receptors (Fc gamma RI/CD64, Fc gamma RII/CD32, Fc gamma RIII/CD16) have been implicated in a number of diseases. Their functional roles such as capture and clearance of immune complexes, antibody-dependent cell cytotoxicity, or cytokine or inflammatory mediator release, make them potential targets for immuno-intervention. In the present review, we will describe how membrane and soluble human Fc epsilon R and Fc gamma R have been already used as targets/tools for immuno-interventions by using monoclonal and bispecific engineered antibodies. Some therapeutic uses of these molecules both in cancer, infectious, and auto-immune diseases are presented.

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Suppressor T Lymphocytes

Webb¹,

Devens²

1998

Encyclopedia of Immunology

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Soluble FcR Block Suppressor T Cell Activity at Low Concentrationin VitroAllowing Isotype-Specific Antibody Production

Cited by 7 publications

References 0 publications

Identification and characterization of a Fc Receptor activity on the Toxoplasma gondii tachyzoite

Identification and characterization of a Fc Receptor activity on the Toxoplasma gondii tachyzoite

Fc Receptors as Targets for Immunotherapy

Suppressor T Lymphocytes

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