Activation of inflammasomes is an important aspect of innate immune responses to bacterial infection. Recent studies have linked Vibrio cholerae secreted toxins to inflammasome activation by using murine macrophages. To increase relevance to human infection, studies of inflammasome-dependent cytokine secretion were conducted with the human THP-1 monocytic cell line and corroborated in primary human peripheral blood mononuclear cells (PBMCs). Both El Tor and classical strains of V. cholerae activated ASC (apoptosis-associated speck-like protein-containing a CARD domain)-dependent release of interleukin-1 (IL-1) when cultured with human THP-1 cells, but the pattern of induction was distinct, depending on the repertoire of toxins the strains produced. El Tor biotype strains induced release of IL-1 dependent on NOD-like receptor family pyrin domain-containing 3 (NLRP3) and ASC due to the secreted pore-forming toxin hemolysin. Unlike in studies with mouse macrophages, the MARTX toxin did not contribute to IL-1 release from human monocytic cells. Classical biotype strains, which do not produce either hemolysin or the MARTX toxin, activated low-level IL-1 release that was induced by cholera toxin (CT) and dependent on ASC but independent of NLRP3 and pyroptosis. El Tor strains likewise showed increased IL-1 production dependent on CT when the hemolysin gene was deleted. In contrast to studies with murine macrophages, this phenotype was dependent on a catalytically active CT A subunit capable of inducing production of cyclic AMP and not on the B subunit. These studies demonstrate that the induction of the inflammasome in human THP-1 monocytes and in PBMCs by V. cholerae varies with the biotype and is mediated by both NLRP3-dependent and -independent pathways. V ibrio cholerae is the causative agent of the diarrheal disease cholera. The O1 serogroup, which is most associated with disease, is divided into two biotypes, classical and El Tor. Classical strains were responsible for the six cholera pandemics that occurred during the 19th century and the first half of the 20th century and are noted for their severe clinical presentation. In 1961, the El Tor strains emerged as the cause of the ongoing seventh pandemic, completely displacing the classical strains from the environment and as a cause of cholera in humans (1). These strains colonize the intestine more effectively and spread between hosts more efficiently but cause fewer deaths and significantly more asymptomatic colonization (2).The primary virulence factor for pandemic cholera strains is cholera toxin (CT), an ADP-ribosylating toxin that disables the G␣ s subunit, resulting in increased cyclic AMP (cAMP) production and secretion of fluid from enterocytes due to the opening of chloride channels. The toxin is composed of the catalytically active A (CTA) subunit associated with five CTB subunits that bind to surface GM 1 gangliosides, facilitating toxin endocytosis (3). In addition to enterotoxigenic activity, CT has also been demonstrated to have immunomodulat...