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MHC class II-specific T cells can develop in the CD8 lineage when CD4 is absent
E O Matechak1, N Killeen, S M Hedrick
1Laboratory of Cellular and Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0420, USA.
Immunity
|April 1, 1996
Summary
The CD4 coreceptor influences T cell lineage commitment. In CD4-deficient mice, T cells with a class II-specific T cell receptor (TCR) mature into the CD8 lineage, not the CD4 lineage.
Area of Science:
- Immunology
- Cell Biology
- Developmental Biology
Background:
- T cell maturation involves specific corecognition of MHC molecules by T cell receptors (TCRs) and coreceptors.
- CD4 T cells typically recognize MHC class II, while CD8 T cells recognize MHC class I.
- The role of coreceptors in guiding T cell lineage commitment is crucial but not fully understood.
Purpose of the Study:
- To investigate the role of the CD4 coreceptor in T cell development and lineage commitment.
- To determine if CD4 influences T cell lineage choice independently of its role in MHC recognition.
Main Methods:
- Generation of CD4-deficient mice.
- Expression of a transgenic class II-specific T cell receptor (TCR) in these mice.
- Analysis of T cell maturation and lineage commitment in the absence of CD4.
Main Results:
- A significant number of T cells matured in CD4-deficient mice expressing a class II-specific TCR.
- These mature T cells were found in the CD8 lineage, contrary to expectations.
- When CD4 was present, T cells with the same TCR predominantly chose the CD4 lineage.
Conclusions:
- The CD4 coreceptor plays a significant role in directing T cell lineage commitment, even for TCRs not strictly dependent on coreceptor for MHC recognition.
- Coreceptor presence can influence lineage choice, suggesting a quantitative signaling model for CD4/CD8 commitment.
- These findings provide new insights into the mechanisms governing T cell differentiation.