Mice homozygous for the B2m^tm1Unc targeted mutation have little if any MHC class I protein expression on the cell surface. There are few CD4- CD8+ cytotoxic T-cells and under some circumstances there is 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. Hemachromatosis has been noted in certain genetic backgrounds.

Development

The B2m^tm1Unc allele was generated in the laboratory of Dr. Beverly Koller and Dr. Oliver Smithies at The University of North Carolina at Chapel Hill. This targeted disruption used the 129P2/OlaHsd derived E14TG2a ES cell line. The C3H/HeJ strain was produced in the laboratory of Dr. Derry Roopenian at The Jackson Laboratory by backcrossing the B2m^tm1Unc allele from a segregating 129;B6 background 13 times to C3H/HeJ inbred mice.

Genetics

B2m^tm1Unc

Allele Symbol: B2m^tm1Unc

Allele Name	targeted mutation 1, University of North Carolina
Allele Type	Targeted (Null/Knockout)
Allele Synonym(s)	b2m^null; beta2M-; beta2m⁰; beta2m^null; beta2m^o; beta2m^tm1Unc; beta2MKO; beta2-m-KO; I⁰; MHC-I^-
Gene Symbol and Name	B2m, beta-2 microglobulin
Gene Synonym(s)
Strain of Origin	129P2/OlaHsd
Chromosome	2
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

Disease/Phenotype

Disease Terms

Research Areas By Phenotype

This mouse can be used to support research in many areas including:

Genotype: B2m^tm1Unc related

Hematological Research
- Anemia, Iron Deficiency and Transport Defects
  - hemochromatosis
Internal/Organ Research
- Liver Defects
  - hemochromatosis
Immunology, Inflammation and Autoimmunity Research
- Immunodeficiency
  - MHC class I deficiency
Research Tools
- Immunology, Inflammation and Autoimmunity Research
  - MHC class I deficiency
Metabolism Research
- Hemochromatosis
  - iron metabolism defects

Mammalian Phenotype Terms by Genotype

The following phenotype information is associated with a similar, but not exact match to this JAX^® Mice strain

Genotype: B2m^tm1Unc/B2m^tm1Unc
B6.129P2-B2m/DcrJ

endocrine/exocrine gland phenotype

abnormal pancreas morphology
- mice develop peri-islet T cell aggregates >30 weeks of age

immune system phenotype

decreased susceptibility to autoimmune diabetes
- mice do not develop spontaneous diabetes compared to wild-type NOD controls
- when splenocytes from diabetic donors are transferred into lethally-irradiated 8-week old recipients, female mice remain normoglycemic for about 17 weeks before developing hyperglycemia/diabetes; kinetics are much slower than in B2m-null, Tg(GFAP-B2m)Mdos (line 9 or 14) transgenic mice
- (line 9 or 14) transgenic mice

decreased susceptibility to bacterial infection
- at day 12 and 14 post-infection with a lethal low dose of IEO, mice exhibit only mild liver pathology, few apoptotic foci in the liver and preserved lymphoid tissue cellularity
- mice are highly resistant to infection with a monocytotropic Ehrlichia bacteria from Ixodes ovatrus ticks (IOE) following infection with either a low or high dose of IOE, 90% of mice survive a low dose with mild illness and all mice succumb to a high dose
- mice have lower burdens of Ehrlichia bacteria in the lungs and spleen following infection than do wild-type mice
- following infection with IEO, CD8+ T cells in the spleen are reduced (1.5%+/-0.1% of splenocytes compared to 9.7%+/-0.7% of splenocytes in wild-type mice)
- to a high dose

increased T-helper 1 cell number
- following infection with a monocytotropic Ehrlichia bacteria from Ixodes ovatrus ticks (IOE), the number of interferon-gamma producing CD4+ Th1 cells in the spleen on day 8 and day 12 is increased relative to in infected wild-type mice

abnormal tumor necrosis factor level
- following infection with a lethal low dose of a monocytotropic Ehrlichia bacteria from Ixodes ovatrus ticks (IOE), induces less TNF-alpha than in infected wild-type mice

increased IgM level

increased susceptibility to infection induced morbidity/mortality
- following infection with either a low or high dose of IOE, 90% of mice survive a low dose and all mice succumb to a high dose

decreased CD8-positive, alpha-beta T cell number
- following infection with a monocytotropic Ehrlichia bacteria from Ixodes ovatrus ticks (IOE), CD8+ T cells in the spleen are reduced (1.5%+/-0.1% of splenocytes compared to 9.7%+/-0.7% of splenocytes in wild-type mice)
- in uninfected mice the number of CD8+ T cells in the spleen is reduced compared to in wild-type mice

decreased IgG level

abnormal interleukin level
- following infection with a lethal low dose of a monocytotropic Ehrlichia bacteria from Ixodes ovatrus ticks (IOE), induces less IL-10 than in infected wild-type mice

mortality/aging

increased susceptibility to infection induced morbidity/mortality
- following infection with either a low or high dose of IOE, 90% of mice survive a low dose and all mice succumb to a high dose

hematopoietic system phenotype

increased T-helper 1 cell number
- following infection with a monocytotropic Ehrlichia bacteria from Ixodes ovatrus ticks (IOE), the number of interferon-gamma producing CD4+ Th1 cells in the spleen on day 8 and day 12 is increased relative to in infected wild-type mice

increased IgM level

decreased CD8-positive, alpha-beta T cell number
- following infection with a monocytotropic Ehrlichia bacteria from Ixodes ovatrus ticks (IOE), CD8+ T cells in the spleen are reduced (1.5%+/-0.1% of splenocytes compared to 9.7%+/-0.7% of splenocytes in wild-type mice)
- in uninfected mice the number of CD8+ T cells in the spleen is reduced compared to in wild-type mice

decreased IgG level

homeostasis/metabolism phenotype

abnormal interleukin level
- following infection with a lethal low dose of a monocytotropic Ehrlichia bacteria from Ixodes ovatrus ticks (IOE), induces less IL-10 than in infected wild-type mice

abnormal tumor necrosis factor level
- following infection with a lethal low dose of a monocytotropic Ehrlichia bacteria from Ixodes ovatrus ticks (IOE), induces less TNF-alpha than in infected wild-type mice

decreased circulating serum albumin level

Genotype: B2m^tm1Unc/B2m^tm1Unc
involves: 129P2/OlaHsd * C57BL/6

immune system phenotype

absent CD8-positive, alpha-beta T cells
- deficient in CD4-CD8+ T cells
- CD8+CD4- T cells from the thymus of five week old mice are almost non-existent in comparison to control (0.8% vs. 6.7%), however, total numbers of alpha beta T cells and CD8-CD4+ T cells do not differ significantly from control

abnormal T cell number
- mucosal-associated invariant T cells (MAIT) that express the canonical mVa19-Ja33 TCR rearrangement and are typically found in the gut lamina propia are virtually absent in these mice
- when these mice serve as bone marrow donors, MAIT T cells are absent in the gut of irradiated hosts
- when wild-type bone marrow is transferred into these mice, MAIT T cells are found in the gut

decreased level of surface class I molecules
- surface expression of class I molecules in cells from lymph nodes, spleen and thymus cannot be detected by flow cytometry

hematopoietic system phenotype

absent CD8-positive, alpha-beta T cells
- deficient in CD4-CD8+ T cells
- CD8+CD4- T cells from the thymus of five week old mice are almost non-existent in comparison to control (0.8% vs. 6.7%), however, total numbers of alpha beta T cells and CD8-CD4+ T cells do not differ significantly from control

abnormal T cell number
- when wild-type bone marrow is transferred into these mice, MAIT T cells are found in the gut
- mucosal-associated invariant T cells (MAIT) that express the canonical mVa19-Ja33 TCR rearrangement and are typically found in the gut lamina propia are virtually absent in these mice
- when these mice serve as bone marrow donors, MAIT T cells are absent in the gut of irradiated hosts

Genotype: B2m^tm1Unc/B2m⁺
involves: 129P2/OlaHsd * C57BL/6

hematopoietic system phenotype

decreased CD8-positive, alpha-beta T cell number
- numbers of CD8+CD4- T cells from the thymus of five week old mice are reduced in comparison to control (4.9% vs. 6.7%), however, in peripheral lymphoid tissues numbers of CD8+CD4- T cells do not differ from control

immune system phenotype

decreased CD8-positive, alpha-beta T cell number
- numbers of CD8+CD4- T cells from the thymus of five week old mice are reduced in comparison to control (4.9% vs. 6.7%), however, in peripheral lymphoid tissues numbers of CD8+CD4- T cells do not differ from control

decreased level of surface class I molecules
- surface expression of class I molecules in cells from lymph nodes are reduced in comparison to control

References

Additional References

Sproule TJ; Jazwinska EC; Britton RS; Bacon BR; Fleming RE; Sly WS; Roopenian DC. 2001. Naturally variant autosomal and sex-linked loci determine the severity of iron overload in beta 2-microglobulin-deficient mice. Proc Natl Acad Sci U S A 98(9):5170-4PubMed: 11309500 MGI: J:68985

Additional - B2m^tm1Unc related

Technical Support

CONTACT TECHNICAL SUPPORT

Genotyping Protocols
- Standard PCR:B2m
- Genotyping resources and troubleshooting
Citation
When using the Β₂M- mouse strain in a publication, please cite the originating article(s) and include JAX stock #004040 in your Materials and Methods section.

Animal Health Reports

Facility Barrier Level Descriptions

Production of mice from cryopreserved embryos or sperm occurs in a maximum barrier room, G200

Pricing & Availability

Cryo Recovery

Domestic
International

Live Mouse

Age

Genotype

Price

weeks

Cryorecovery - Pricing

Service/Product	Description	Price
	Homozygous for B2m<tm1Unc>, 1 pair minimum

Payment Terms and Conditions

Terms are granted by individual review and stated on the customer invoice(s) and account statement. These transactions are payable in U.S. currency within the granted terms. Payment for services, products, shipping containers, and shipping costs that are rendered are expected within the payment terms indicated on the invoice or stated by contract. Invoices and account balances in arrears of stated terms may result in The Jackson Laboratory pursuing collection activities including but not limited to outside agencies and court filings.

The Jackson Laboratory's Genotype Promise

The Jackson Laboratory has rigorous genetic quality control and mutant gene genotyping programs to ensure the genetic background of JAX® Mice strains as well as the genotypes of strains with identified molecular mutations. JAX® Mice strains are only made available to researchers after meeting our standards. However, the phenotype of each strain may not be fully characterized and/or captured in the strain data sheets. Therefore, we cannot guarantee a strain's phenotype will meet all expectations. To ensure that JAX® Mice will meet the needs of individual research projects or when requesting a strain that is new to your research, we suggest ordering and performing tests on a small number of mice to determine suitability for your particular project. We do not guarantee breeding performance and therefore suggest that investigators order more than one breeding pair to avoid delays in their research.

Terms Of Use

General Terms and Conditions

Questions about Terms of Use

Licensing Information

Phone: 207-288-6470

Email: TechTran@jax.org

Also Known As:Β2M-

Genetic overview

Research Applications

Base Price

Detailed Description

Development

B2mtm1Unc

Allele Symbol: B2mtm1Unc

Disease Terms

Research Areas By Phenotype

This mouse can be used to support research in many areas including:

Genotype: B2mtm1Unc related

Mammalian Phenotype Terms by Genotype

Genotype: B2mtm1Unc/B2mtm1UncB6.129P2-B2m/DcrJ

endocrine/exocrine gland phenotype

immune system phenotype

mortality/aging

hematopoietic system phenotype

homeostasis/metabolism phenotype

Genotype: B2mtm1Unc/B2mtm1Uncinvolves: 129P2/OlaHsd * C57BL/6

immune system phenotype

hematopoietic system phenotype

Genotype: B2mtm1Unc/B2m+involves: 129P2/OlaHsd * C57BL/6

hematopoietic system phenotype

immune system phenotype

References

Additional References

Additional - B2mtm1Unc related

Genotyping Protocols

Citation

Animal Health Reports

Production of mice from cryopreserved embryos or sperm occurs in a maximum barrier room, G200

Live Mouse

Cryorecovery - Pricing

Payment Terms and Conditions

The Jackson Laboratory's Genotype Promise

Terms Of Use

Licensing Information

Also Known As:Β₂M-

B2m^tm1Unc

Allele Symbol: B2m^tm1Unc

Genotype: B2m^tm1Unc related

Genotype: B2m^tm1Unc/B2m^tm1Unc
B6.129P2-B2m/DcrJ

Genotype: B2m^tm1Unc/B2m^tm1Unc
involves: 129P2/OlaHsd * C57BL/6

Genotype: B2m^tm1Unc/B2m⁺
involves: 129P2/OlaHsd * C57BL/6

Additional - B2m^tm1Unc related