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Expression and function of the UM4D4 antigen in human thymus
1Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0531.
Journal of Immunology (Baltimore, Md. : 1950)
|October 1, 1989
Summary
UM4D4, a novel T cell surface molecule, is expressed on peripheral T cells and thymocytes, including neuroendocrine thymic epithelium. Anti-UM4D4 activates T cells and thymocytes, suggesting a dual role in T cell differentiation.
Area of Science:
- Immunology
- Cell Biology
- T cell development
Background:
- UM4D4 is a novel T cell surface molecule distinct from the Ag receptor and CD2.
- It is expressed on resting and activated peripheral blood T cells.
- Alternative T cell activation pathways may be crucial for thymic differentiation.
Purpose of the Study:
- To investigate the expression and function of UM4D4 in the human thymus.
- To determine if UM4D4 plays a role in thymic T cell differentiation.
- To explore the presence of UM4D4 on thymic epithelial cells.
Main Methods:
- Flow cytometry to analyze UM4D4 expression on thymocytes and peripheral T cells.
- Monoclonal antibody stimulation (anti-UM4D4) to assess T cell activation.
- Dual-color fluorescence microscopy to examine UM4D4 co-localization with thymic epithelial antigens.
Main Results:
- UM4D4 is expressed on 6% of thymocytes, with highest expression on CD4-CD8- subsets (18%), many of which are gamma delta-TCR+.
- Anti-UM4D4 demonstrated mitogenic and co-mitogenic activity with PMA or IL-2 on thymocytes.
- UM4D4 was detected on a subset of neuroendocrine thymic epithelial cells in the cortex and medulla.
Conclusions:
- UM4D4 is expressed on a subset of thymocytes and neuroendocrine thymic epithelium.
- Anti-UM4D4 can activate thymocytes, indicating a role in T cell activation and differentiation.
- UM4D4 may have a dual function in T cell differentiation by acting on both thymocytes and thymic epithelial cells.