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Nonclassical behavior of the mouse CD1 class I-like molecule
M Teitell1, H R Holcombe, L Brossay
1Department of Microbiology and Immunology, University of California at Los Angeles 90095, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|March 1, 1997
Summary
Mouse CD1 (mCD1) molecules, unlike classical class I, do not require the transporter associated with antigen processing (TAP) for cell surface expression. This suggests mCD1 presents unique ligands to T cells.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Mouse CD1 (mCD1) is a class I-like molecule encoded outside the Major Histocompatibility Complex (MHC).
- Classical class I molecules present antigens to CD8+ T cells and require beta2-microglobulin and the transporter associated with antigen processing (TAP) for surface expression.
Purpose of the Study:
- To investigate the cell surface expression requirements of mouse CD1 (mCD1).
- To compare the properties of mCD1 with classical class I antigen-presenting molecules.
Main Methods:
- Analysis of mCD1 surface expression in T lymphocyte transfectants and thymocytes.
- Assessment of mCD1 binding to CD8alphabeta heterodimers.
- Evaluation of mCD1 surface expression in TAP-deficient cells (RMA-S and Drosophila melanogaster cells) at varying temperatures.
Main Results:
- mCD1 requires beta2-microglobulin for stable cell-surface expression, similar to classical class I molecules.
- mCD1 binds to mouse CD8alphabeta heterodimers, potentially activating CD8+ T cells.
- mCD1 surface expression is not impaired at high temperatures in TAP-deficient cells, indicating TAP independence.
Conclusions:
- mCD1 exhibits distinct antigen-processing requirements compared to classical class I molecules, notably its independence from TAP.
- This TAP-independent pathway may allow mCD1 to present a unique repertoire of ligands.
- The properties of mCD1 contribute to the selection of diverse mCD1-reactive T cell populations.