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IgG response is impaired in H2-c-fos transgenic mice
Abstract:
Transgenic mice carrying the proto-oncogene c-fos under the control of H-2Kb promoter (c-fos mice) were generated from (C57BL/6 x SJL)F2 mice. One line was backcrossed with C57BL/6 mice for 10 generations. These semi-congenic c-fos mice express exogenous c-fos RNA in their hematopoietic tissues. The following immunological states are apparent. (i) Titers of serum IgM, IgG, and IgA of naive c-fos were within the control range. (ii) These mice could not produce primary IgG antibody specific for immunized antigen. (iii) Production of primary IgM and IgA antibody to the antigen was within the control range. (iv) There were no IgG memory B cells generated in the spleens of c-fos mice. (v) Activities of antigen-presenting cells and carrier-specific helper T cells from c-fos mice were normal. These findings strongly suggest that the immune abnormality of c-fos mice is in limiting B cell function to the production of IgG to immunized antigens.
Insights
Transgenic c-fos mice exhibit normal IgM and IgA antibody production but lack the ability to generate IgG antibodies or IgG memory B cells. This indicates a specific B cell defect in IgG production.
Area of Science:
- Immunology
- Genetics
- Oncology
Background:
- The proto-oncogene c-fos plays a role in cellular regulation.
- Transgenic models are crucial for studying gene function in vivo.
- Hematopoietic tissues are central to immune responses.
Purpose of the Study:
- To investigate the immunological consequences of expressing exogenous c-fos in hematopoietic tissues.
- To characterize the B cell function and antibody production in c-fos transgenic mice.
Main Methods:
- Generation of transgenic mice expressing c-fos under the H-2Kb promoter.
- Backcrossing to C57BL/6 mice for semi-congenic lines.
- Analysis of serum antibody titers (IgM, IgG, IgA) and B cell populations.
Main Results:
- c-fos mice showed normal IgM and IgA antibody production.
- These mice were unable to produce primary IgG antibodies against specific antigens.
- No generation of IgG memory B cells was observed in c-fos mice.
- Antigen-presenting cells and T helper cell activities remained normal.
Conclusions:
- The immune abnormality in c-fos mice is specifically linked to impaired B cell function in IgG production.
- Exogenous c-fos expression in hematopoietic tissues disrupts IgG antibody synthesis.
- These findings highlight a critical role for c-fos in regulating B cell differentiation and antibody class switching.