Sticks in time?

[Robert C. Newton]

> >         Concerning adhesion marker VLA4. It appears from textboks and 
> > reviews that I've read that the ligand for VLA4 is VCAM-1. Yet peak  >
> expression of VCAM on endothelium occurs a few hours after activation, 
> > whereas VLA is expressed some days later (hence its name!). Does
> either > of  these molecules have a more important ligand, or is their
> some other >  mechanism at work?

Vla4 is constitutively expressed on cells such as monocytes and eosinophils
so only VCAM-1 expression on endothelial cells and cell activation appears to
be needed to allow the interaction (for example see Chuluyan and Issekutz,
1993, J. Clin. Invest. 92:2768).  In addition Vla4 interacts with the CS-1
domain of fibronectin (see Wayner et al., 1988, J. Cell. Biol. 107:1881). 
Perhaps a more important interaction in inflammed tissues.




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