These B2m knock-out mice exhibit little if any MHC class I protein expression on the cell surface with deficiency in CD8+ cytotoxic T-cells, NK1+ T cells, and decreased levels of serum Ig.
Dr. Derry Roopenian, The Jackson Laboratory
Mice homozygous for the B2mtm1Unc targeted mutation have little if any MHC class I protein expression on the cell surface. There are few CD8+ cytotoxic T-cells and under some circumstances a compensatory increase in CD4+ cytotoxic T-cells. Immune responses involving CD8+ T-cells are severely deficient providing a model to assess the role of CD8+ cells and class I MHC in various experimental systems. Other traits of B2M deficient mice include: NK cell deficiency, NK1+ T cells deficiency and decreased levels of serum Ig. Some forms of lupus autoimmunity are severely reduced. (Christianson, J Immunol 156:4932-9, 1996). Hemachromatosis has been noted in certain genetic backgrounds (Rothenberg BE, Voland JR, Proc Natl Acad Sci USA 93:1529-34, 1996). The B2mtm1Un mutation backcrossed to the NOD/Lt strain serves as a MHC class I-negative, CD8+ deficient diabetes resistant stock for comparison to the NOD/LtJ strain (Stock No. 001976). The elimination of cell surface MHC class I expression blocks both insulitis and autoimmune diabetes in NOD/Lt mice. A disadvantage of this strain is that CD4+ T cells are not tolerant to MHC class I positive syngeneic cells. These mice provide an excellent source for insulitis-free, MHC class I-bare NOD islets for transplantation studies.
The B2mtm1Unc mutant strain was developed in the laboratory of Dr. Beverly Koller and Dr. Oliver Smithies at the University of North Carolina at Chapel Hill. It was generated by a targeted disruption of the B2m gene. The 129-derived E14TG2a ES cell line was used. The NOD/LtJ strain was produced in the laboratory of Dr. Derry Roopenian at The Jackson Laboratory by backcrossing the B2mtm1Unc mutation 10 times to NOD/LtJ inbred mice.
|Allele Name||targeted mutation 1, University of North Carolina|
|Allele Type||Targeted (Null/Knockout)|
|Allele Synonym(s)||b2mnull; beta2M-; beta2m0; beta2mnull; beta2mo; beta2mtm1Unc; beta2MKO; beta2-m-KO; I0; MHC-I-|
|Gene Symbol and Name||B2m, beta-2 microglobulin|
|Strain of Origin||129P2/OlaHsd|
|Molecular Note||Insertion of a neomycin-resistance gene into the second exon.|
|Mutations Made By|| |
Dr. Oliver Smithies, University of North Carolina at Chapel Hill
This B2mtm1Unc strain is maintained by mating heterozygous and homozygous mice. These mice are immunodeficient and need to be maintained in a high barrier environment with sterile food and water. Expected coat color from breeding is Albino.
When using the NOD β2m KO mouse strain in a publication, please cite the originating article(s) and include JAX stock #002309 in your Materials and Methods section.