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Binding sites for peptidoglycan on mouse lymphocytes.
1Department of Microbiology and Immunology, Indiana University School of Medicine, Gary 46408.
Cellular Immunology
|October 1, 1987
Summary
Peptidoglycan (PG) specifically binds to murine lymphocytes, suggesting this interaction is key for lymphocyte activation. High molecular weight PG, but not smaller fragments, binds and stimulates B-cells.
Area of Science:
- Immunology
- Molecular Biology
- Biochemistry
Background:
- Peptidoglycan (PG) is a known B-cell mitogen and polyclonal activator.
- Understanding the molecular mechanisms of PG-induced lymphocyte activation is crucial.
Purpose of the Study:
- To investigate the specific binding of peptidoglycan (PG) to murine lymphocytes.
- To determine if PG binding is related to lymphocyte activation.
Main Methods:
- Rosette formation assay using PG-sensitized erythrocytes.
- Direct binding assay with 125I-labeled PG.
- Competitive binding experiments to determine affinity and specificity.
Main Results:
- 34% of splenic lymphocytes formed PG rosettes, with specific inhibition by free PG.
- 125I-PG demonstrated specific and non-specific binding to lymphocytes.
- Low affinity binding sites (KD = 1.2-4.6 X 10(-7) M) were identified.
- Binding affinity correlated with lymphocyte-stimulating capacity; only high molecular weight PG showed significant binding and activation.
Conclusions:
- Murine lymphocytes possess specific binding sites for peptidoglycan (PG).
- The binding of PG to these sites appears to be involved in the activation of lymphocytes by PG.
- High molecular weight PG is responsible for both binding and mitogenic activity.