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Decoration of T-independent antigen with ligands for CD22 and Siglec-G can suppress immunity and induce B cell tolerance in vivo.

Duong BH, Tian H, Ota T, Completo G, Han S, Vela JL, Ota M, Kubitz M, Bovin N, Paulson JC, Paulson J, Nemazee D - J. Exp. Med. (2009)

Bottom Line: Although mutations in CD22 and its signaling machinery have been associated with dysregulated B cell development and autoantibody production, previous analyses failed to identify a tolerance defect in antigen-specific mutant B cells.Our results support a role for siglecs in B cell self-/nonself-discrimination, namely suppressing responses to self-associated antigens while permitting rapid "missing self"-responses to unsialylated multimeric antigens.The results suggest use of siglec ligand antigen constructs as an approach for inducing tolerance.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA.

ABSTRACT
Autoreactive B lymphocytes first encountering self-antigens in peripheral tissues are normally regulated by induction of anergy or apoptosis. According to the "two-signal" model, antigen recognition alone should render B cells tolerant unless T cell help or inflammatory signals such as lipopolysaccharide are provided. However, no such signals seem necessary for responses to T-independent type 2 (TI-2) antigens, which are multimeric antigens lacking T cell epitopes and Toll-like receptor ligands. How then do mature B cells avoid making a TI-2-like response to multimeric self-antigens? We present evidence that TI-2 antigens decorated with ligands of inhibitory sialic acid-binding Ig-like lectins (siglecs) are poorly immunogenic and can induce tolerance to subsequent challenge with immunogenic antigen. Two siglecs, CD22 and Siglec-G, contributed to tolerance induction, preventing plasma cell differentiation or survival. Although mutations in CD22 and its signaling machinery have been associated with dysregulated B cell development and autoantibody production, previous analyses failed to identify a tolerance defect in antigen-specific mutant B cells. Our results support a role for siglecs in B cell self-/nonself-discrimination, namely suppressing responses to self-associated antigens while permitting rapid "missing self"-responses to unsialylated multimeric antigens. The results suggest use of siglec ligand antigen constructs as an approach for inducing tolerance.

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Design of sialylated and unsialylated TI-2–like conjugates and comparison of initial antibody responses elicited in C57BL/6 mice. (A) Structure of immunogenic and tolerogenic conjugates. Shown schematically are PA conjugates carrying both NP and the nonsiglec-binding carbohydrate Galβ1-4GlcNAc (NP–PA), compared with the conjugates NP–PA–NeuGc or NP–PA–bNeuGc. (B and C) Mice were immunized 7 d previously with 20 µg of the indicated conjugates in PBS. Unless otherwise stated, the antigen dose given in all experiments of this study was 20 µg in PBS. Results shown are representative of at least three independent experiments. All statistical tests given used the two-tailed Student’s t test. Means + SD are shown. *, P < 0.05; ***, P < 0.005. (B) Antibody response to NP–PA–bNeuGc (+) versus NP–PA (−; n = 4/group). (C) Antibody response to NP–PA–NeuGc (+) versus NP–PA (−; n = 7/group).
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fig2: Design of sialylated and unsialylated TI-2–like conjugates and comparison of initial antibody responses elicited in C57BL/6 mice. (A) Structure of immunogenic and tolerogenic conjugates. Shown schematically are PA conjugates carrying both NP and the nonsiglec-binding carbohydrate Galβ1-4GlcNAc (NP–PA), compared with the conjugates NP–PA–NeuGc or NP–PA–bNeuGc. (B and C) Mice were immunized 7 d previously with 20 µg of the indicated conjugates in PBS. Unless otherwise stated, the antigen dose given in all experiments of this study was 20 µg in PBS. Results shown are representative of at least three independent experiments. All statistical tests given used the two-tailed Student’s t test. Means + SD are shown. *, P < 0.05; ***, P < 0.005. (B) Antibody response to NP–PA–bNeuGc (+) versus NP–PA (−; n = 4/group). (C) Antibody response to NP–PA–NeuGc (+) versus NP–PA (−; n = 7/group).

Mentions: To see if incorporating siglec ligands into TI-2 antigen affects B cell in vivo responses, PA was conjugated with nitrophenol (NP) hapten and one of two glycans found to be ligands of CD22 and Siglec-G. We selected the natural sialoside NeuGc and the high affinity siglec ligand bNeuGc to ensure that adequate competition with cis ligands would be achieved. As an immunogenic control, a corresponding conjugate (NP–PA) was prepared with a glycan lacking sialic acid (Galβ1-4GlcNAc). The resulting polymers contained ∼200 NP haptens and 400 glycan moieties (Fig. 2 A).


Decoration of T-independent antigen with ligands for CD22 and Siglec-G can suppress immunity and induce B cell tolerance in vivo.

Duong BH, Tian H, Ota T, Completo G, Han S, Vela JL, Ota M, Kubitz M, Bovin N, Paulson JC, Paulson J, Nemazee D - J. Exp. Med. (2009)

Design of sialylated and unsialylated TI-2–like conjugates and comparison of initial antibody responses elicited in C57BL/6 mice. (A) Structure of immunogenic and tolerogenic conjugates. Shown schematically are PA conjugates carrying both NP and the nonsiglec-binding carbohydrate Galβ1-4GlcNAc (NP–PA), compared with the conjugates NP–PA–NeuGc or NP–PA–bNeuGc. (B and C) Mice were immunized 7 d previously with 20 µg of the indicated conjugates in PBS. Unless otherwise stated, the antigen dose given in all experiments of this study was 20 µg in PBS. Results shown are representative of at least three independent experiments. All statistical tests given used the two-tailed Student’s t test. Means + SD are shown. *, P < 0.05; ***, P < 0.005. (B) Antibody response to NP–PA–bNeuGc (+) versus NP–PA (−; n = 4/group). (C) Antibody response to NP–PA–NeuGc (+) versus NP–PA (−; n = 7/group).
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2812539&req=5

fig2: Design of sialylated and unsialylated TI-2–like conjugates and comparison of initial antibody responses elicited in C57BL/6 mice. (A) Structure of immunogenic and tolerogenic conjugates. Shown schematically are PA conjugates carrying both NP and the nonsiglec-binding carbohydrate Galβ1-4GlcNAc (NP–PA), compared with the conjugates NP–PA–NeuGc or NP–PA–bNeuGc. (B and C) Mice were immunized 7 d previously with 20 µg of the indicated conjugates in PBS. Unless otherwise stated, the antigen dose given in all experiments of this study was 20 µg in PBS. Results shown are representative of at least three independent experiments. All statistical tests given used the two-tailed Student’s t test. Means + SD are shown. *, P < 0.05; ***, P < 0.005. (B) Antibody response to NP–PA–bNeuGc (+) versus NP–PA (−; n = 4/group). (C) Antibody response to NP–PA–NeuGc (+) versus NP–PA (−; n = 7/group).
Mentions: To see if incorporating siglec ligands into TI-2 antigen affects B cell in vivo responses, PA was conjugated with nitrophenol (NP) hapten and one of two glycans found to be ligands of CD22 and Siglec-G. We selected the natural sialoside NeuGc and the high affinity siglec ligand bNeuGc to ensure that adequate competition with cis ligands would be achieved. As an immunogenic control, a corresponding conjugate (NP–PA) was prepared with a glycan lacking sialic acid (Galβ1-4GlcNAc). The resulting polymers contained ∼200 NP haptens and 400 glycan moieties (Fig. 2 A).

Bottom Line: Although mutations in CD22 and its signaling machinery have been associated with dysregulated B cell development and autoantibody production, previous analyses failed to identify a tolerance defect in antigen-specific mutant B cells.Our results support a role for siglecs in B cell self-/nonself-discrimination, namely suppressing responses to self-associated antigens while permitting rapid "missing self"-responses to unsialylated multimeric antigens.The results suggest use of siglec ligand antigen constructs as an approach for inducing tolerance.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA.

ABSTRACT
Autoreactive B lymphocytes first encountering self-antigens in peripheral tissues are normally regulated by induction of anergy or apoptosis. According to the "two-signal" model, antigen recognition alone should render B cells tolerant unless T cell help or inflammatory signals such as lipopolysaccharide are provided. However, no such signals seem necessary for responses to T-independent type 2 (TI-2) antigens, which are multimeric antigens lacking T cell epitopes and Toll-like receptor ligands. How then do mature B cells avoid making a TI-2-like response to multimeric self-antigens? We present evidence that TI-2 antigens decorated with ligands of inhibitory sialic acid-binding Ig-like lectins (siglecs) are poorly immunogenic and can induce tolerance to subsequent challenge with immunogenic antigen. Two siglecs, CD22 and Siglec-G, contributed to tolerance induction, preventing plasma cell differentiation or survival. Although mutations in CD22 and its signaling machinery have been associated with dysregulated B cell development and autoantibody production, previous analyses failed to identify a tolerance defect in antigen-specific mutant B cells. Our results support a role for siglecs in B cell self-/nonself-discrimination, namely suppressing responses to self-associated antigens while permitting rapid "missing self"-responses to unsialylated multimeric antigens. The results suggest use of siglec ligand antigen constructs as an approach for inducing tolerance.

Show MeSH