Figure-1.

Diagrammatic representation of phagocytic cells activation and subsequent migration at the site of infection. Initially, macrophages in the tissue detect the presence of pathogens through CD-14 and toll-like receptors and secrete inflammatory cytokines such as IL-1 and tumor necrosis factor which further stimulate the release of interleukin (IL-8) from Weibel-Palade bodies as well as expression of both P-selectin and E-selectin on the surface of endothelial cells (ECs). IL-8 binds to the chemokine receptors (CXCR1 and CXCR2) on the surface of polymorphonuclear leukocytes (PMNs) which causes PMNs activation. Activated neutrophils use L-selectin and integrin for slowing down and tethering to the ECs, respectively. Matrix metalloproteinases help in transmigration and chemokine receptors help PMNs to move toward the chemotactic gradients and perform their functions by various mechanisms. (Source: Mohanned Naif Alhussien and Ajay Kumar Dang).