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Peptide dependence of major histocompatibility complex class II specific alloreactive responses
D Vidović1, J I Toral, D R Bolin
1Discovery Research, Hoffmann-La Roche, Inc., Nutley, New Jersey 07110-1199, USA.
Scandinavian Journal of Immunology
|March 31, 1998
Summary
Transgenic mice with single peptides complexed to major histocompatibility complex (MHC) class II molecules cannot trigger mixed lymphocyte reactions (MLR). Blocking peptides also inhibit MLR, suggesting alloreactivity targets multiple peptides presented by MHC molecules.
Area of Science:
- Immunology
- Transplantation Immunology
- Molecular Biology
Background:
- Major histocompatibility complex (MHC) class II molecules present peptides to T cells, initiating immune responses.
- Allogeneic mixed lymphocyte reactions (MLR) are a key model for studying T cell recognition of foreign MHC molecules.
- The specific peptides presented by allogeneic MHC molecules and their role in MLR remain incompletely understood.
Purpose of the Study:
- To investigate the role of specific peptides presented by MHC class II molecules in triggering primary allogeneic MLR.
- To determine if a single peptide presented by MHC class II molecules is sufficient to elicit an allogeneic MLR.
- To elucidate the nature of the antigenic targets in allogeneic T cell responses.
Main Methods:
- Utilized transgenic mice engineered to express single peptides complexed to MHC class II molecules.
- Co-cultured splenic cells from these transgenic mice with lymphocytes from MHC class II congenic mouse strains.
- Employed HLA-DR-blocking peptides in experiments with chimeric transgenic mice to assess their impact on MLR.
- Measured T cell proliferation and activation as indicators of MLR.
Main Results:
- Splenic cells from transgenic mice presenting a single peptide-MHC class II complex failed to induce primary MLR.
- A single HLA-DR-blocking peptide effectively abrogated the MLR-stimulating capacity of splenocytes from chimeric transgenic mice.
- These findings demonstrate that T cells recognize multiple peptides presented by allogeneic MHC molecules.
Conclusions:
- The primary alloreactive T cell response is directed against a diverse repertoire of peptides presented by allogeneic MHC molecules, not just a single dominant peptide.
- Understanding peptide presentation by MHC molecules is crucial for manipulating immune responses in transplantation and autoimmunity.
- This study provides critical insights into the specificity of T cell recognition in allogeneic settings.