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Adhesion molecules

المؤلف:  Siraj A. Misbah, Gavin P. Spickett, and Virgil A. S. H. Dalm

المصدر:  Chapel and Haeneys Essentials of Clinical Immunology (2022)

الجزء والصفحة:  7th edition , P15

2026-10-25

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 Adhesion molecules comprise another set of cell surface glycoproteins with a pivotal role, not only in immune responses by mediating cell- to- cell adhesion, but also for adhesion between cells and extracellular matrix proteins. Adhesion molecules are grouped into two major families: (i) integrins and (ii) selectins (Table 1). The migration of leucocytes to sites of inflammation is dependent on three key sequential steps mediated by adhesion molecules (Fig. 1): rolling of leucocytes along activated endothelium is selectin dependent; tight adhesion of leucocytes to endothelium is integrin dependent; and transendothelial migration occurs under the influence of chemokines. Cytokines also influence the selectin- and integrin- dependent phases.

Table1. Examples of clinically important adhesion molecule

Fig1. Adhesion molecules and leucocyte–endothelial interactions.

Integrins are heterodimers composed of non- covalently associated α and β subunits. Depending on the structure of the β subunit, integrins are subdivided into five families (β1 to β5 integrins). β1 and β2 integrins play a key role in leucocyte endothelial interaction. β1 integrins mediate lymphocyte and monocyte binding to the endothelial adhesion receptor called vascular cell adhesion molecule (VCAM- 1). β2 integrins share a common β chain (CD18) that pairs with a different α chain (CD11a, b, c) to form three separate molecules (CD11a CD18, CD11b CD18, CD11c CD18); they also mediate strong binding of leucocytes to the endothelium. Examples in other systems include β3 to β5 integrins mediating cell adhesion to extracellular matrix proteins such as fibronectin and vitronectin in the skin and laminin receptor in muscle.

The selectin family is composed of three glycoproteins designated by the prefixes E (endothelial), L (leucocyte) and P (platelet) to denote the cells on which they were first described. Selectins bind avidly to carbohydrate molecules on leucocytes and endothelial cells and regulate the homing of the cells to sites of inflammation (see  Table 2).

Table2. Proteins controlling classical and alternative complement pathways *