Purity >98%. NOD-like receptor (NLR) pyrin domain-containing protein 3 (NLRP3) senses pathogen-derived, environmental, and host-derived factors and initiates the formation of inflammasomes, complexes involved in complex diseases including multiple sclerosis, type 2 diabetes, Alzheimer's disease, and atherosclerosis. MCC950 is a selective inhibitor of NLRP3, blocking the release of IL-1Beta in macrophages primed with LPS and activated with ATP or nigericin (IC50 = 7.5 nM). It does not inhibit NLRC4, AIM2, TLR2 signaling, or priming of NLRP3. MCC950 prevents oligomerization of apoptosis-associated speck-like protein containing a CARD (ASC) in cells stimulated with LPS and nigericin. MCC-950 is active in vivo, blocking the production of IL-1Beta and enhancing survival in mouse models of multiple sclerosis and cryopyrin-associated periodic syndrome. It is also active in ex vivo samples from individuals with Muckle-Wells syndrome.