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The major receptor for C-reactive protein on leukocytes is fcgamma receptor II.

Bharadwaj D, Stein MP, Volzer M, Mold C, Du Clos TW - J. Exp. Med. (1999)

Bottom Line: On monocytic cell lines, treatment with Bt(2)cAMP increased FcgammaRII expression and enhanced CRP binding.CRP also specifically precipitated FcgammaRI and FcgammaRII from the monocytic cell line, THP-1.It is suggested that the major receptor for CRP on phagocytic cells is FcgammaRII.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico 87108, USA.

ABSTRACT
C-reactive protein (CRP) is an acute phase serum protein that shares several functions with immunoglobulin (Ig)G including complement activation and binding to receptors on monocytes and neutrophils. The identity of the receptor for CRP has been the target of extensive research. We previously determined that CRP binds to the high affinity receptor for IgG, FcgammaRI (CD64). However, this interaction could not account for the majority of binding of CRP to neutrophils or monocytic cells. We now determine that CRP also interacts with FcgammaRIIa (CD32), the low affinity receptor for IgG on monocytes and neutrophils. COS-7 cells were transfected with a construct containing the human FcgammaRIIA cDNA. CRP binding and the presence of CD32 were detected by mAb and analyzed by two-color flow cytometry. Cells expressing CD32 bound CRP in a dose-dependent and saturable manner consistent with receptor binding. CRP bound to transfectants and K-562 cells with similar kinetics, and in both cases binding was completely inhibited by aggregated IgG. On monocytic cell lines, treatment with Bt(2)cAMP increased FcgammaRII expression and enhanced CRP binding. CRP also specifically precipitated FcgammaRI and FcgammaRII from the monocytic cell line, THP-1. It is suggested that the major receptor for CRP on phagocytic cells is FcgammaRII.

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CRP binding to FcγRIIa is inhibited by aggIgG. K-562 cells or COS-7 cells transfected with the FcγRIIA plasmid, pcDSRα296, were incubated with 25 μg/ml of CRP in the presence of increasing concentrations of aggIgG. CRP binding was detected with 2C10 and PE-GAM as described in Materials and Methods. Results are expressed as the increase in gMCF compared with the secondary antibody controls. The solid line represents binding of CRP to K-562 cells and the dotted line represents the binding of CRP to transfected COS cells in the absence of aggIgG.
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Figure 3: CRP binding to FcγRIIa is inhibited by aggIgG. K-562 cells or COS-7 cells transfected with the FcγRIIA plasmid, pcDSRα296, were incubated with 25 μg/ml of CRP in the presence of increasing concentrations of aggIgG. CRP binding was detected with 2C10 and PE-GAM as described in Materials and Methods. Results are expressed as the increase in gMCF compared with the secondary antibody controls. The solid line represents binding of CRP to K-562 cells and the dotted line represents the binding of CRP to transfected COS cells in the absence of aggIgG.

Mentions: To determine if CRP was binding to the same site on FcγRII as IgG, the effect of aggIgG on CRP binding was examined. As shown in Fig. 3, aggIgG inhibited CRP binding to K-562 cells in a dose-dependent manner with 50% inhibition at ∼80 μg/ml of aggIgG. This finding is consistent with previous reports by us 1011 and others 567 that aggIgG effectively blocks CRP binding to its receptor. A nearly identical inhibition profile was obtained using aggIgG to inhibit CRP binding to CD32-transfected COS cells (Fig. 3). For both cell types, aggIgG did not affect the background binding of the secondary antibodies measured in the absence of CRP.


The major receptor for C-reactive protein on leukocytes is fcgamma receptor II.

Bharadwaj D, Stein MP, Volzer M, Mold C, Du Clos TW - J. Exp. Med. (1999)

CRP binding to FcγRIIa is inhibited by aggIgG. K-562 cells or COS-7 cells transfected with the FcγRIIA plasmid, pcDSRα296, were incubated with 25 μg/ml of CRP in the presence of increasing concentrations of aggIgG. CRP binding was detected with 2C10 and PE-GAM as described in Materials and Methods. Results are expressed as the increase in gMCF compared with the secondary antibody controls. The solid line represents binding of CRP to K-562 cells and the dotted line represents the binding of CRP to transfected COS cells in the absence of aggIgG.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2195602&req=5

Figure 3: CRP binding to FcγRIIa is inhibited by aggIgG. K-562 cells or COS-7 cells transfected with the FcγRIIA plasmid, pcDSRα296, were incubated with 25 μg/ml of CRP in the presence of increasing concentrations of aggIgG. CRP binding was detected with 2C10 and PE-GAM as described in Materials and Methods. Results are expressed as the increase in gMCF compared with the secondary antibody controls. The solid line represents binding of CRP to K-562 cells and the dotted line represents the binding of CRP to transfected COS cells in the absence of aggIgG.
Mentions: To determine if CRP was binding to the same site on FcγRII as IgG, the effect of aggIgG on CRP binding was examined. As shown in Fig. 3, aggIgG inhibited CRP binding to K-562 cells in a dose-dependent manner with 50% inhibition at ∼80 μg/ml of aggIgG. This finding is consistent with previous reports by us 1011 and others 567 that aggIgG effectively blocks CRP binding to its receptor. A nearly identical inhibition profile was obtained using aggIgG to inhibit CRP binding to CD32-transfected COS cells (Fig. 3). For both cell types, aggIgG did not affect the background binding of the secondary antibodies measured in the absence of CRP.

Bottom Line: On monocytic cell lines, treatment with Bt(2)cAMP increased FcgammaRII expression and enhanced CRP binding.CRP also specifically precipitated FcgammaRI and FcgammaRII from the monocytic cell line, THP-1.It is suggested that the major receptor for CRP on phagocytic cells is FcgammaRII.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico 87108, USA.

ABSTRACT
C-reactive protein (CRP) is an acute phase serum protein that shares several functions with immunoglobulin (Ig)G including complement activation and binding to receptors on monocytes and neutrophils. The identity of the receptor for CRP has been the target of extensive research. We previously determined that CRP binds to the high affinity receptor for IgG, FcgammaRI (CD64). However, this interaction could not account for the majority of binding of CRP to neutrophils or monocytic cells. We now determine that CRP also interacts with FcgammaRIIa (CD32), the low affinity receptor for IgG on monocytes and neutrophils. COS-7 cells were transfected with a construct containing the human FcgammaRIIA cDNA. CRP binding and the presence of CD32 were detected by mAb and analyzed by two-color flow cytometry. Cells expressing CD32 bound CRP in a dose-dependent and saturable manner consistent with receptor binding. CRP bound to transfectants and K-562 cells with similar kinetics, and in both cases binding was completely inhibited by aggregated IgG. On monocytic cell lines, treatment with Bt(2)cAMP increased FcgammaRII expression and enhanced CRP binding. CRP also specifically precipitated FcgammaRI and FcgammaRII from the monocytic cell line, THP-1. It is suggested that the major receptor for CRP on phagocytic cells is FcgammaRII.

Show MeSH
Related in: MedlinePlus