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A novel adhesion molecule in the murine thymic microenvironment: functional and biochemical analysis
N Imami1, H M Ladyman, E Spanopoulou
1Department of Immunology, Royal Postgraduate Medical School, Hammersmith Hospital, London.
Developmental Immunology
|January 1, 1992
Summary
The monoclonal antibody (mAb) 4F1 identifies a novel adhesion molecule, 4F1-antigen (4F1-Ag), expressed on thymic epithelial cells and leukocytes. This molecule plays a role in T-cell differentiation and function.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- The monoclonal antibody (mAb) 4F1 recognizes the 4F1-antigen (4F1-Ag) on mouse thymic cortical epithelium.
- Activated leukocytes and transformed thymocytes also express 4F1-Ag, detectable by flow cytometry.
Purpose of the Study:
- To characterize the molecular and functional properties of the 4F1-antigen.
- To investigate the role of 4F1-Ag in T-cell development and function.
Main Methods:
- Western blotting to determine the molecular weight and glycosylation of 4F1-Ag.
- Phosphatidylinositol-specific phospholipase C (PI-PLC) treatment to assess membrane linkage.
- Functional blocking experiments using mAb 4F1 in mixed lymphocyte reactions (MLR) and cytotoxic T-cell assays.
Main Results:
- 4F1-Ag exists in four molecular forms (29, 32, 40, and 43 kD) with N-linked carbohydrates, consistent on epithelium and lymphocytes.
- 4F1-Ag is partially sensitive to PI-PLC on cortical epithelium but resistant on lymphoid cells, suggesting both transmembrane and phosphoinositol-linked forms.
- mAb 4F1 inhibited T-cell proliferation in MLR, cytotoxic T-cell activity, and adhesion of thymocytes to thymic epithelial cells.
Conclusions:
- 4F1-Ag is a novel adhesion molecule involved in intrathymic T lymphocyte differentiation.
- 4F1-Ag likely plays a role in peripheral T-cell function and cell-cell interactions within the thymus.