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Severe attenuation of the B cell immune response in Msh2-deficient mice.

Vora KA, Tumas-Brundage KM, Lentz VM, Cranston A, Fishel R, Manser T - J. Exp. Med. (1999)

Bottom Line: Recently, results obtained from mice with targeted inactivations of postreplication DNA mismatch repair (MMR) genes have been interpreted to demonstrate a direct role for MMR in antibody variable (V) gene hypermutation.These include lack of progression of the germinal center (GC) reaction associated with increased intra-GC apoptosis, severely diminished antigen-specific immunoglobulin G responses, and near absence of anamnestic responses.Interpretation of the impact of an MMR deficiency on the mechanism of V gene somatic hypermutation could be easily confounded by these perturbations.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology and The Kimmel Cancer Institute, Jefferson Medical College, Philadelphia, Pennsylvania 19107, USA.

ABSTRACT
Recently, results obtained from mice with targeted inactivations of postreplication DNA mismatch repair (MMR) genes have been interpreted to demonstrate a direct role for MMR in antibody variable (V) gene hypermutation. Here we show that mice that do not express the MMR factor Msh2 have wide-ranging defects in antigen-driven B cell responses. These include lack of progression of the germinal center (GC) reaction associated with increased intra-GC apoptosis, severely diminished antigen-specific immunoglobulin G responses, and near absence of anamnestic responses. Mice heterozygous for the Msh2 deficiency display an "intermediate" phenotype in these regards, suggesting that normal levels of Msh2 expression are critical for the B cell response. Interpretation of the impact of an MMR deficiency on the mechanism of V gene somatic hypermutation could be easily confounded by these perturbations.

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IgG expression by Msh2-deficient B cells in vitro. Small  dense splenic B cells derived from pools of cells obtained from three mice  of each genotype were cultured for 4.5 d with either LPS (25 μg/ml) or  LPS (25 μg/ml) and recombinant murine IL-4 (50 ng/ml), and supernatants were harvested. Levels of total IgG3 and IgG1 in these supernatants  were then determined by ELISA, as described in Materials and Methods.  All assays were performed in triplicate, and error bars are shown.
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Figure 7: IgG expression by Msh2-deficient B cells in vitro. Small dense splenic B cells derived from pools of cells obtained from three mice of each genotype were cultured for 4.5 d with either LPS (25 μg/ml) or LPS (25 μg/ml) and recombinant murine IL-4 (50 ng/ml), and supernatants were harvested. Levels of total IgG3 and IgG1 in these supernatants were then determined by ELISA, as described in Materials and Methods. All assays were performed in triplicate, and error bars are shown.

Mentions: Since our serological and immunohistochemical analysis of the B cell response of Msh2-deficient mice revealed a severe attenuation of the IgG response, induction of isotype class switching in vitro was examined using small dense splenic B cells. B cells were cultured with LPS, which results in low levels of switching to IgG3 and IgG2b in normal B cells, or with LPS plus IL-4, which suppresses switching to IgG3 and drives efficient switching to IgG1 and IgE isotypes in normal B cells (33). Levels of class-switched IgG1 and IgG3–secreted antibody were then determined by ELISA. Msh2 +/+, +/−, and −/− B cells stimulated with LPS gave rise to levels of IgG3 that did not differ greatly, and Msh2 −/− B cells produced only slightly reduced amounts of this isotype (Fig. 7). Little or no IgG1 was produced by any of these cell types in response to LPS. In response to stimulation with LPS plus IL-4, Msh2 +/+, +/−, and −/− B cells gave rise to similar levels of IgG1, and little IgG3. These data argue that the regulation and efficiency of isotype class switching in vitro are not greatly perturbed by an Msh2 deficiency in B cells.


Severe attenuation of the B cell immune response in Msh2-deficient mice.

Vora KA, Tumas-Brundage KM, Lentz VM, Cranston A, Fishel R, Manser T - J. Exp. Med. (1999)

IgG expression by Msh2-deficient B cells in vitro. Small  dense splenic B cells derived from pools of cells obtained from three mice  of each genotype were cultured for 4.5 d with either LPS (25 μg/ml) or  LPS (25 μg/ml) and recombinant murine IL-4 (50 ng/ml), and supernatants were harvested. Levels of total IgG3 and IgG1 in these supernatants  were then determined by ELISA, as described in Materials and Methods.  All assays were performed in triplicate, and error bars are shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2192912&req=5

Figure 7: IgG expression by Msh2-deficient B cells in vitro. Small dense splenic B cells derived from pools of cells obtained from three mice of each genotype were cultured for 4.5 d with either LPS (25 μg/ml) or LPS (25 μg/ml) and recombinant murine IL-4 (50 ng/ml), and supernatants were harvested. Levels of total IgG3 and IgG1 in these supernatants were then determined by ELISA, as described in Materials and Methods. All assays were performed in triplicate, and error bars are shown.
Mentions: Since our serological and immunohistochemical analysis of the B cell response of Msh2-deficient mice revealed a severe attenuation of the IgG response, induction of isotype class switching in vitro was examined using small dense splenic B cells. B cells were cultured with LPS, which results in low levels of switching to IgG3 and IgG2b in normal B cells, or with LPS plus IL-4, which suppresses switching to IgG3 and drives efficient switching to IgG1 and IgE isotypes in normal B cells (33). Levels of class-switched IgG1 and IgG3–secreted antibody were then determined by ELISA. Msh2 +/+, +/−, and −/− B cells stimulated with LPS gave rise to levels of IgG3 that did not differ greatly, and Msh2 −/− B cells produced only slightly reduced amounts of this isotype (Fig. 7). Little or no IgG1 was produced by any of these cell types in response to LPS. In response to stimulation with LPS plus IL-4, Msh2 +/+, +/−, and −/− B cells gave rise to similar levels of IgG1, and little IgG3. These data argue that the regulation and efficiency of isotype class switching in vitro are not greatly perturbed by an Msh2 deficiency in B cells.

Bottom Line: Recently, results obtained from mice with targeted inactivations of postreplication DNA mismatch repair (MMR) genes have been interpreted to demonstrate a direct role for MMR in antibody variable (V) gene hypermutation.These include lack of progression of the germinal center (GC) reaction associated with increased intra-GC apoptosis, severely diminished antigen-specific immunoglobulin G responses, and near absence of anamnestic responses.Interpretation of the impact of an MMR deficiency on the mechanism of V gene somatic hypermutation could be easily confounded by these perturbations.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology and The Kimmel Cancer Institute, Jefferson Medical College, Philadelphia, Pennsylvania 19107, USA.

ABSTRACT
Recently, results obtained from mice with targeted inactivations of postreplication DNA mismatch repair (MMR) genes have been interpreted to demonstrate a direct role for MMR in antibody variable (V) gene hypermutation. Here we show that mice that do not express the MMR factor Msh2 have wide-ranging defects in antigen-driven B cell responses. These include lack of progression of the germinal center (GC) reaction associated with increased intra-GC apoptosis, severely diminished antigen-specific immunoglobulin G responses, and near absence of anamnestic responses. Mice heterozygous for the Msh2 deficiency display an "intermediate" phenotype in these regards, suggesting that normal levels of Msh2 expression are critical for the B cell response. Interpretation of the impact of an MMR deficiency on the mechanism of V gene somatic hypermutation could be easily confounded by these perturbations.

Show MeSH
Related in: MedlinePlus