Integrins are heterodimers formed by two subunits, an alpha chain and a beta chain.
There are 17 INTEGRIN-ALPHA chains and 8 INTEGRIN-BETA chains.
The association of an INTEGRIN-ALPHA chain and INTEGRIN-BETA chain leads to 25 different integrins.
Adhesion of T lymphocytes to extracellular matrix and/or other cells is essential
in both their activation and migration. Among the cell surface molecules involved in
adhesion functions, integrins mediates both cell-cell and cell-matrix interactions.
The integrin family has been divided into three main subfamilies according to the β chain.
Three main subfamilies:
- The β1 chain (CD29, GPIIa), which defines the VLA subfamily, is highly expressed on memory
T cells and is implicated in different cellular functions .
Indeed, T cell stimulation by phorbol esters, anti-CD3 or anti-CD2 antibodies, increase the
adhesion of the T cells to fibronectin which is a ligand of VLA-4 and VLA-5 and to laminin
which is a ligand of VLA-6. In addition, laminin, fibronectin and vascular cell adhesion
molecule 1, which is a second ligand of VLA-4 can deliver a positive costimulatory activation
signal within T cells via their VLA receptor.
- The β2 chain (CD18) defines the Leu-cam subfamily (Leucocyte cell adhesion molecules CD11/CD18).
- The β3 chain (CD61, GPIIIa) defines the cytoadhesin family.