Caspases are intracellular proteases that cleave substrates involved in either apoptosis or infection, with different branches of the family dedicated to those two functions in mammals. The NACHT domain mediates oligomerization of mammalian NLRs, related to the nucleotide binding NB ARC domain HDAC3 inhibitor of CED 4 in D. elegans. Evidence has been presented to claim that the LRRs reduce NACHT mediated oligomerization, with this repression relieved upon binding microbial ligands. In this regard, NLRs represent the intracellular complement for the cell surface TLR family receptors associated with innate immunity in animals and are extremely related to intracellular host defense proteins of plants. Here we show that the human NLR member of the family NALP1 is controlled by interactions with antiapoptotic proteins Bcl 2 and Bcl X, which suppress NALP1 mediated activation of caspase 1 and lower production of the caspase 1 substrate interleukin 1b. NALP1 resembles CED 4 because it contains CARD and nucleotide-binding oligomerization areas. The Bcl 2/Bcl X mediated reduction of caspase1 Immune system activating NALP1 ergo offers a mammalian analog for the C. elegans process and shows a novel procedure linking host defense and apoptosis. NALP1 was found to keep company with Bcl 2 and Bcl Xby coimmunoprecipitation studies using lysates prepared from transfected HEK293T cells expressing epitopetagged proteins. Of the six individual antiapoptotic Bcl 2family proteins, only Bcl 2 and Bcl Xassociated with NALP1. On the other hand, Bcl W, Mcl 1, Bfl 1, and Bcl B didn’t associate with NALP1, or did various proapoptotic Bcl 2 family proteins, including Bax, Bak, Bid, and Bcl H. Similar conclusions were reached using angiogenesis regulation in vitro protein binding assays where NALP1 containing cell lysates were incubated with bacteriaproduced GST fusion proteins. To explore whether NALP1 is exclusive among NLR household proteins in its ability to bind Bcl 2 and Bcl X, we com-pared NALP1 with NALP2, 3, and 4, which all contain PYRIN, NACHT, and LRR domains like NALP1. We also examined the proteins ASC and Pyrin, that incorporate PYRIN domains. But, among these proteins examined, only NALP1 connected with Bcl Xand Bcl 2. NALP1 forms a multiprotein caspase initiating complex called the inflammasome, which includes NALP1, bipartite adaptor protein ASC, and caspase 1. Both lipopolysaccharide and the peptidoglycan portion muramyldipeptide have already been reported to promote NALP1 inflammasome assembly. To explore the interaction of endogenous Bcl 2 and Bcl Xwith endogenous NALP1, we performed experiments with THP 1 monocytes that had been dif-ferentiated into macrophages applying phorbol ester TPA and followed methods that were previously published in which treatment of these cells with either LPS or MDP was shown to cause inflammasome assembly, caspase 1 activation, and IL 1b release.