urate crystals are initially phagocytosed by synoviocytes, which then release prostaglandins, lysosome enzymes,and interleukin-1 which attract and activate polymorphonuclear leukocytes (PMN) and mononuclear phagocytes (MNP)(macrophages).
attracted by these chemotactic mediators, polymorphonuclear leukocytes and mononuclear phagocytes migrate into the joint space and amplify the ongoing inflammatory process.
In the later phases of the attack, increased numbers of mononuclear phagocyte appear, ingest the urate crystal, and release more inflammatory mediators.