Platelet-activating factor (PAF): Signalling and adhesion in cell-cell interactions

Abstract

Signalling by PAF is closely linked to adhesive interactions between cells of the inflammatory and vascular systems. It acts as a juxtacrine signal that alters the activity of β2 integrins on myeloid leukocytes (Figure 1), and works in concert with P-selectin at the surfaces of endothelial cells (Figure 2 and text). Observations in models of flow23 and in vivo33 support the original experiments using cultured endothelium under static conditions that indicated that PAF acts at this vascular interface. P- selectin modifies and integrates signals delivered through the PAF receptor on monocytes (Figure 4). Adhesion via P-selectin and engagement of β2 integrins modify signals leading to PAF synthesis (text and Figure 5). The intimate relationship between adhesive events and signalling by PAF may be a critical determinant in its roles in physiologic and pathologic responses.