The mouse vitronectin receptor is a T cell activation antigen

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• The T cell activation antigen, recognized by monoclonal antibody H9.2B8, was previously uncharacterized in mice.
• Vitronectin receptor (VNR) is known to bind extracellular matrix proteins via the RGD sequence.
• The function of VNR in T cell activation has been suggested by recent studies.

Purpose of the Study:

• To identify the murine homologue of the vitronectin receptor (VNR) on T cell activation antigens.
• To investigate the expression of VNR on various lymphoid cells.
• To determine the binding capabilities and potential role of VNR in T cell functions.

Main Methods:

• Monoclonal antibody H9.2B8 was used to identify the T cell activation antigen.
• Expression analysis was performed on T cell lines, tumors, and splenocytes.
• Binding assays were conducted with extracellular matrix proteins like fibronectin, fibrinogen, and vitronectin.

Main Results:

• The T cell activation antigen recognized by H9.2B8 is the murine homologue of VNR.
• VNR is expressed on T cell lines, tumors, and Con A-activated splenocytes, but not resting T cells.
• VNR binds fibronectin, fibrinogen, and vitronectin via the RGD sequence; no novel beta chains were found pairing with the VNR alpha chain.

Conclusions:

• Vitronectin receptor (VNR) is expressed on murine lymphoid cells.
• VNR's ability to bind extracellular matrix proteins suggests a role in T cell adhesion and migration.
• VNR may function as an accessory molecule in T cell activation, highlighting its importance in mouse T cell immunity.