skh1 Antibody

What is the genetic background of SKH1 mice and how does it affect immunological studies?

SKH1 mice carry a homozygous Hairless (Hr) mutation hr (also called Hairless hr/hr or Hairless SKH1/SKH1), which originated from a colony at the Skin and Cancer Hospital of Temple University in 1986 . This commercially available strain is considered outbred, which researchers should account for when designing immunological studies . The hypomorphic mutation affects epithelial cells but notably does not disturb thymocyte differentiation, making these mice valuable for immune function studies . Genotyping for the Hr mutation can be performed using specific primers that produce a 350 base pair product for the wildtype allele and a 250 bp product for the SKH1 mutant allele .

How do the baseline immunological parameters of SKH1 mice compare to C57Bl/6 mice?

SKH1 mice demonstrate comparable immune competence to C57Bl/6 mice with some notable differences. Complete blood counts reveal similar white blood cell counts between the strains, though SKH1 mice show a lower percentage of lymphocytes (70% vs. 83%, p=0.05) without significant differences in absolute lymphocyte counts . The table below summarizes key hematological parameters:

The immunoglobulin profile shows that baseline IgM levels are lower in SKH1 than C57Bl/6 mice (2.66 vs. 3.49 ng/ml, p<0.0001), while baseline serum IgG and IgA levels are not significantly different .

How do T cell populations differ between SKH1 and C57Bl/6 mice?

While major thymocyte subsets (CD4/CD8 double negative, double positive, and single positive) show no significant differences between SKH1 and C57Bl/6 mice, peripheral T cell populations exhibit notable variations . SKH1 mice demonstrate:

• Increased CD3+ cells (4.5 × 10⁵ vs. 2.3 × 10⁵ cells/spleen in SKH1 vs. B6 mice, p=0.02)

• Decreased naïve T cells (1.7 × 10⁵ vs. 3.4 × 10⁵ cells/spleen in SKH1 vs. B6 mice, p=0.008)

• Increased memory T cells (1.4 × 10⁶ vs. 0.13 × 10⁶ cells/spleen in SKH1 vs. B6 mice, p=0.008)

• Mildly reduced CD25+ regulatory T cells (4.7 × 10⁵ vs. 6.0 × 10⁵ cells/spleen in SKH1 vs. B6 mice, p=0.04)

Despite these differences in cell numbers and distribution, functional immune responses remain intact, as demonstrated by lymph node cell proliferative responses to antigen rechallenge .

How suitable are SKH1 mice for combined skin barrier and immunological research?

SKH1 mice represent an excellent model for studies investigating both skin barrier function and immunological responses. These mice are immunocompetent with immune responses similar to C57Bl/6 mice (which have a Th1 bias), while lacking the Th2 bias seen in BALB/c mice . This makes them particularly valuable when researchers need to investigate:

• Skin microbiome and barrier integrity studies

• Dermal and immunological responses to chemical exposures

• Allergic and inflammatory skin conditions

SKH1 mice have been successfully used in studies examining triclosan exposure effects on skin barrier integrity and microbiota composition, with correlated changes in Th2-skewing immune responses . Their furless phenotype provides technical advantages for dermal exposure studies and subsequent skin sample analysis.

What methodological approaches best characterize immune responses in SKH1 skin following chemical exposure?

For comprehensive assessment of immune responses in SKH1 skin after chemical exposure, researchers should implement:

• Immunophenotyping flow cytometry panels to characterize immune cell populations

• Gene expression analysis to detect changes in immune-related genes

• Chemokine/cytokine profiling to assess inflammatory responses

In triclosan exposure studies, these approaches revealed that SKH1 mice showed different neutrophil recruitment patterns compared to BALB/c mice . Specifically, while triclosan exposure increased neutrophil numbers in BALB/c skin after 2, 4, and 7 days of exposure, no significant differences were observed in SKH1 skin . This was further confirmed by examining chemokine expression, where SKH1 and BALB/c mice showed different expression patterns of neutrophil-recruiting chemokines Cxcl1 and Cxcl2 following triclosan exposure .

How do the functional T cell responses of SKH1 mice compare to other mouse strains despite differences in T cell subset distribution?

Despite the numerical differences in T cell subsets between SKH1 and C57Bl/6 mice, functional T cell responses remain remarkably similar. When challenged with keyhole limpet hemocyanin (KLH) antigen:

• Lymph node cell in vitro proliferative responses to antigen rechallenge were preserved in SKH1 mice

• Responses to anti-CD3 stimulation were similar to C57Bl/6 mice, with SKH1 mice exhibiting a significant increase compared to C57Bl/6

• In vivo delayed-type hypersensitivity assays showed that inflammatory responses to KLH following initial sensitization and subsequent challenge did not differ significantly between SKH1 and C57Bl/6 mice

These findings suggest that despite alterations in peripheral T cell numbers and subset distribution, SKH1 mice maintain functional T cell-dependent immune responses comparable to standard immunocompetent mouse strains.

What controls should be implemented when using SKH1 mice for immunological studies?

When designing immunological studies with SKH1 mice, researchers should consider:

• Including C57Bl/6 mice as comparative controls, especially for studies focused on T cell responses or neutrophil recruitment

• For studies involving skin exposures, consider including both shaved and unshaved control groups to account for potential effects of shaving on immune responses

• For humoral immunity studies, researchers should be aware of the lower baseline IgM levels in SKH1 mice compared to C57Bl/6

• When analyzing T cell functional responses, include both in vitro proliferation assays and in vivo challenges to ensure comprehensive assessment

Additionally, researchers should note that SKH1 mice show increased memory T cells and decreased naïve T cells compared to C57Bl/6 mice, which may influence experimental outcomes in studies of adaptive immunity .

How should researchers account for strain-specific differences when interpreting immune response data from SKH1 mice?

When interpreting data from SKH1 mice, researchers should consider:

• The outbred nature of the commercially available SKH1 strain, which may introduce greater variability compared to inbred strains like C57Bl/6

• The lower percentage of lymphocytes but similar absolute lymphocyte counts compared to C57Bl/6 mice

• Decreased baseline IgM levels but comparable IgG and IgA levels

• Different peripheral T cell subset distributions, particularly increased memory T cells and decreased naïve T cells

• Strain-specific differences in chemokine expression patterns (e.g., Cxcl1 and Cxcl2) following chemical exposure

How suitable are SKH1 mice for cancer research requiring intact immune surveillance?

SKH1 mice maintain immune surveillance capabilities comparable to standard immunocompetent mouse strains, making them valuable for cancer research. When SKH1 mice were interbred with a genetically-engineered mouse model of alveolar rhabdomyosarcoma:

• Tumor histology was indistinguishable between mice with and without the SKH1 mutation

• Immunohistochemical features such as myogenin positivity were unchanged by the presence of the homozygous SKH1 mutation

• Tumor-associated immune cell infiltration, including CD56+ NK cells and CD163+ macrophages, was unaffected by the SKH1 mutation

• Tumor growth rates were indistinguishable between mice carrying 0 or 2 SKH1 mutations at the Hr locus

These findings demonstrate that SKH1 mice maintain normal anti-tumor immune responses, making them suitable for cancer research requiring intact immune function.

What advantages do SKH1 mice offer for combined imaging and immunological studies?

SKH1 mice provide significant advantages for studies combining optical imaging with immunological assessment:

• Their furless phenotype improves signal detection in optical imaging by reducing reporter signal attenuation that would otherwise occur due to fur

• They are particularly valuable for imaging deep-seated tumors expressing luminescent or fluorescent reporters

• The absence of fur facilitates easier monitoring of tumor growth and progression

• Their preserved immune competence allows for accurate assessment of anti-tumor immune responses alongside imaging studies

These advantages make SKH1 mice excellent candidates for interbreeding with other genetically-engineered mouse models of cancer for improved preclinical studies combining imaging with immunological assessment.

How do humoral immune responses in SKH1 mice compare to C57Bl/6 mice following immunization?

Following immunization with keyhole limpet hemocyanin (KLH) antigen:

• SKH1 mice showed lower anti-KLH IgM levels 5 days post-immunization compared to C57Bl/6 mice (0.11 vs. 0.12 ng/ml, p=0.02), consistent with their lower baseline IgM levels

• Two weeks post-immunization, anti-KLH IgG levels were appropriately elevated and similar between SKH1 and C57Bl/6 mice

• CD19 positive B cells from the spleen were comparable between SKH1 and C57Bl/6 mice

These findings indicate that while SKH1 mice have consistently lower IgM levels, their ability to mount appropriate IgG responses following immunization is preserved, suggesting intact B cell function and class switching.

What are the key differences in inflammatory responses between SKH1 and BALB/c mice following dermal chemical exposure?

BALB/c and SKH1 mice show distinct inflammatory responses to dermal chemical exposure, particularly to triclosan:

• Neutrophil recruitment: Triclosan exposure significantly increased neutrophil numbers in BALB/c skin after 2, 4, and 7 days, but no significant difference was observed in SKH1 mouse skin

• Chemokine expression:

  • BALB/c mice showed higher gene expression of Cxcl2 (neutrophil recruitment chemokine) after triclosan exposure, while SKH1 mice did not

  • Cxcl1 expression was significantly higher in BALB/c mice following 2 and 7 days of triclosan exposure, while SKH1 mice only showed increased expression after 7 days

• Effect of shaving: When SKH1 mice were shaved prior to triclosan exposure, no significant differences in neutrophil numbers or chemokine expression were observed compared to unshaved SKH1 mice, suggesting that the differences between strains are not due to shaving procedures

These strain-specific differences highlight the importance of selecting the appropriate mouse strain for dermal exposure studies based on the specific research questions being addressed.