C.129P2(B6)-Igk^tm2Rsky Igh^tm2Rsky/J

Stock number: 012235
Research areas: Immunology, Inflammation and Autoimmunity Research

Description

This double targeted mutation of the immunoglobulin kappa chain complex (Igk) and immunoglobulin heavy chain complex (Igh) genes displays an almost monoclonal B cell population and may be useful in studies of B cell development, receptor editing, tolerance and antibody diversification.

Detailed description

Mice that are homozygous for the targeted mutation are viable, fertile, normal in size and do not display any gross physical or behavioral abnormalities. As expected, most splenic B cells express the 3-83 idiotype, but total B cell number may be lower than wild-type. The 3-83 antibody is non-autoreactive on the H-2^d background, while it is autoreactive on the H-2^b and H-2^k backgrounds. Mice heterozygous for both mutations and/or the H-2^b and H-2^k backgrounds exhibit an increase in frequency and absolute number of lambda-expressing B lymphocytes and a decrease in the expression of the 3-83 idiotype due to Igk RS recombination and Vl to Jl rearrangements. The 3-83KiJk<-> allele lacks endogenous Jk segments, preventing secondary Vk to Jk rearrangements. Mice homozygous for both mutations on the H-2^d, but not H-2^b and H-2^k backgrounds, do not retain 3-83 expression and do not have Vk to Jk recombination events. This strain generates an almost monoclonal B cell population. This mutant mouse strain may be useful in studies of B cell development, receptor editing, tolerance and antibody diversification.

Development

The targeting at the Igh locus was performed to replace the DNA region from upstream of DQ52 to downstream of JH4 with a vector that contains a loxP-flanked neo cassette, followed by the Ig 3-83 heavy chain gene, which includes its promoter region and the rearranged VDJ (with JH1). The construct was electroporated into 129P2/OlaHsd-derived E14.1TG3B1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts. The neomycin cassette was removed by transient transfection with a Cre recombinase expressing plasmid leaving a single loxP site. The resulting chimeric animals were crossed to C57BL/6 mice.

The targeting at the Igk locus was performed to replace the DNA region from upstream of Jk1 to downstream of Jk5 with a vector that contains a loxP-flanked neo cassette, followed by the Ig 3-83 light (kappa-k) chain gene, which includes its promoter region and the rearranged VJ (with Jk2), removing all endogenous Jk segments and preventing secondary Vk-Jk rearrangements. The construct was electroporated into 129P2/OlaHsd-derived E14.1TG3B1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts. The neomycin cassette was removed by transient transfection with a Cre recombinase expressing plasmid leaving a single loxP site 5' to the Vk gene. The resulting chimeric animals were crossed to C57BL/6 mice. Mice carrying the two mutations were bred together and then backcrossed to BALB/c (H2^d) for 10 generations.

Allele

Symbol: Igk^tm2Rsky
Name: targeted mutation 2, Klaus Rajewsky
MGI accession ID: MGI:3688312
Generation method: Targeted
Attributes: Inserted expressed sequence
Marker symbol: Igk
Marker name: immunoglobulin kappa chain complex
Chromosome: 6
Strain of origin: Not Specified
Molecular note: A targeting vector was used to insert a recombined Vk3-83-Jk5 region where all endogenous Jkappa segments are deleted.

Allele

Symbol: Igh^tm2Rsky
Name: targeted mutation 2, Klaus Rajewsky
MGI accession ID: MGI:3689719
Generation method: Targeted
Marker symbol: Igh
Marker name: immunoglobulin heavy chain complex
Chromosome: 12
Strain of origin: 129P2/OlaHsd
Molecular note: The rearranged 3-83 heavy chain was inserted into the IgH^a locus via homologous recombination. A floxed neo selection cassette was also introduced and subsequently removed by Cre mediated recombination.