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Updated: Aug 8, 2026
Isolation, Identification, and Purification of Murine Thymic Epithelial Cells
Published on: August 8, 2014
Identification and characterization of a 100-kD ligand for CD6 on human thymic epithelial cells
D D Patel1, S F Wee, L P Whichard
1Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
Insights
Researchers identified a 100-kD glycoprotein on thymic epithelial cells as a ligand for CD6, a molecule crucial for T cell activation and interactions within the thymus.
Area of Science:
- Immunology
- Cell Biology
Background:
- CD6 is a T cell surface glycoprotein involved in T cell activation.
- CD6 mediates interactions between thymocytes and thymic epithelial cells.
Purpose of the Study:
- To identify the ligand for CD6 on thymic epithelial cells.
- To characterize the interaction between CD6 and its ligand.
Main Methods:
- Indirect immunofluorescence assays with recombinant CD6-immunoglobulin fusion protein (CD6-Rg).
- Screening of monoclonal antibodies (mAbs) to block CD6-Rg binding.
- Covalent cross-linking and trypsin digestion to identify binding partners.
Main Results:
- CD6-Rg bound to a 100-kD glycoprotein (CD6L-100) on thymic epithelial cells.
- Monoclonal antibody J4-81 inhibited CD6-Rg binding, indicating it recognizes the CD6 ligand.
- Monoclonal antibody J3-119 enhanced CD6-Rg binding.
Conclusions:
- A 100-kD glycoprotein on thymic epithelial cells, detected by mAb J4-81, is a ligand for CD6.
- This interaction is important for T cell-thymic epithelial cell communication.
Abstract:
CD6 is a 130-kD glycoprotein expressed on the surface of thymocytes and peripheral blood T cells that is involved in TCR-mediated T cell activation. In thymus, CD6 mediates interactions between thymocytes and thymic epithelial (TE) cells. In indirect immunofluorescence assays, a recombinant CD6-immunoglobulin fusion protein (CD6-Rg) bound to cultured human TE cells and to thymic fibroblasts. CD6-Rg binding to TF and TE cells was trypsin sensitive, and 54 +/- 4% of binding was divalent cation dependent. By screening the blind panel of 479 monoclonal antibodies (mAbs) from the 5th International Workshop on Human Leukocyte Differentiation Antigens for expression on human TE cells and for the ability to block CD6-Rg binding to TE cells, we found one mAb (J4-81) that significantly inhibited the binding of CD6-Rg to TE cells (60 +/- 7% inhibition). A second mAb to the surface antigen identified by mAb J4-81, J3-119, enhanced the binding of CD6-Rg to TE cells by 48 +/- 5%. Using covalent cross-linking and trypsin digestion, we found that mAb J4-81 and CD6-Rg both bound to the same 100-kD glycoprotein (CD6L-100) on the surface of TE cells. These data demonstrate that a 100-kD glycoprotein on TE cells detected by mAb J4-81 is a ligand for CD6.
