The uptake by blood-borne phagocytes of monosodium urate is dependent on heat-labile serum factor(s) and divalent cations

Accumulation in tissues of post-apoptotic cells is a feature frequently observed in patients with systemic lupus erythematosus and in murine models of systemic autoimmune diseases. One of the endogenous danger molecules released by secondarily necrotic cells is monosodium urate (MSU), which is already established to be the causative agent of gout. Here, we show that MSU is taken up by eosinophils, neutrophils and monocytes in a process involving (a) heat-labile serum factor(s) and divalent cations. The uptake induces the release of the pro-inflammatory cytokines IL-1 beta/IL-18/TNF alpha and IL-6/IL-8 by monocytes and PMN, respectively.