CBy.129P2(B6)-Igh^tm1Mnz/J

Stock number: 007775
Strain synonyms: B1-8 High Affinity (BALB/cByJ background)
Research areas: Immunology, Inflammation and Autoimmunity Research

Description

In combination with immunoglobulin lambda light chain, this heavy chain variable (V) region produces antibody that binds hapten NP (4-hydroxy-3-nitrophenylacetyl). A Trp to Leu point mutation at codon 33 results in a 40-fold increase in antigen binding affinity (B1-8^hi). Despite the significantly enhanced affinity for NP, there is only a 2-3 fold difference in the T-independent proliferative response of B cells that carry high or low affinity receptors. In T cell-dependent responses there is no difference in the ability of B1-8 high vs. B1-8 low affinity cells to enter germinal center reactions. However, high affinity B cells were recruited preferentially in response to both T cell-dependent and T cell-independent antigens.

Detailed description

Mice homozygous for this targeted mutation are viable and fertile and do not display any gross physical or behavioral abnormalities. In combination with immunoglobulin lambda light chain, this heavy chain variable (V) region produces antibody that binds hapten NP (4-hydroxy-3-nitrophenylacetyl). A Trp to Leu point mutation at codon 33 results in a 40-fold increase in antigen binding affinity (B1-8^hi). Despite the significantly enhanced affinity for NP, there is only a 2-3 fold difference in the T-independent proliferative response of B cells that carry high or low affinity receptors. In T cell-dependent responses there is no difference in the ability of B1-8 high vs. B1-8 low affinity cells to enter germinal center reactions. However, high affinity B cells were recruited preferentially in response to both T cell-dependent and T cell-independent antigens. Expression has been verified by immunostaining cells that carry the mutation. The phenotype of this mutation on the BALB/cBy background is not known to differ from that on the C57BL/6 background (Stock No. 007594).

Development

PCR was used to introduce a point mutation conferring higher affinity 4-hydroxy-3-nitrophenyl)acetyl (NP)-binding to Igh (V_HB1-8): TGG->TTG (codon 33 Trp->Leu). A targeting vector incorporating a 5' floxed neomycin cassette in addition to the point mutation was transfected into 129P2/OlaHsd-derived E14 embryonic stem (ES) cells. Positive clones were injected into C57BL/6 blastocysts, and the resulting chimeric males were bred to C57BL/6 EIIA-Cre females to delete the neomycin gene, and leave a loxP site. Mice were backcrossed to C57BL/6 congenic background CD45.1 (Ptprc^a) mice for at least 12 generations by the donating laboratory, then backcrossed to BALB/cBy for 10 generations. This strain does not carry the Ptprc^a allele.

Allele

Symbol: Igh^tm1Mnz
Name: targeted mutation 1, Michel C Nussenzweig
MGI accession ID: MGI:3712224
Generation method: Targeted
Marker symbol: Igh
Marker name: immunoglobulin heavy chain complex
Chromosome: 12
Strain of origin: 129P2/OlaHsd
Molecular note: PCR was used to introduce a point mutation conferring higher affinity 4-hydroxy-3-nitrophenyl)acetyl (NP)-binding to Igh-V (VHB1-8): TGG->TTG (codon 33 Trp->Leu). A targeting vector incorporating a 5' floxed neomycin cassette in addition to the point mutation was transfected into 129P2/OlaHsd-derived E14 embryonic stem (ES) cells.