Rolling: It is the process of transient adhesion of leukocytes with the endothelial cells The weak and transient interactions involved in rolling are mediated by the selectin family of adhesion molecules Selectins are receptors expressed on leukocytes and endothelium that contain an extracellular domain that binds sugars. Three members of this family are:- E-selectin (also called CD62E), expressed on Endothelial cells and interact with sialyl lewis x receptor on leukocyte. P-selectin (CD62P), present on Platelets and endothelium and interact with sialyl lewis x receptor on leukocyte. L-selectin (CD62L), on the surface of most Leukocytes interacts with glycoprotein adhesion molecules (GlyCAM-1), Mad CAM-1 and CD34 on endothelial cells. Endothelial Molecule Leukocyte Molecule Major Role Selectins and selectin Ligands P-selectin sialyl-lewis X-modified proteins Rolling E-selectin sialyl-lewis X-modified proteins Rolling and adhesion GlyCam-I,CD34 L-selectin Rolling(neutrophils,monocytes) Adhesion: It is firm attachment of the leukocytes to the endothelial cells. Firm adhesion is mediated by a family of heterodimeric leukocyte surface proteins called integrins Endothelial molecule Leukocyte molecule Major role Integrins and integrin ligands ICAM-1 CD 11/CD 18 (Integrins) Adhesion, arrest, transmigration VCAM-1 VLA 4, LPAM-1 adhesion Transmigration/diapedesis: The step in the process of the migration of the leukocytes through the endothelium Endothelial Molecule Leukocyte Molecule Major role CD 31(PECAM) CD 31(homotypic interaction) transmigration reference:- Robbins and coltran pathological basis of disease, 9th edition, page 76