Figure 2

Activation of mast cells (MCs) in intestinal inflammation. Colonic MCs are activated by Ig-free light chains (IgLCs) produced by B cells and by adenosine triphosphate (ATP) released by damaged epithelial cells, activated monocytes by bacterial stimulation and bacteria. Extracellular ATP is recognized by the P2X receptors on MCs (green loops) and leads to production of inflammatory cytokines (for example, interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNFα), chemokines (for example, CCL2, CXCL1 and CXCL2), lipid mediators (for example, leukotrienes) and proteases (for example, tryptase).