FIG 1.

Rapid, ASC-dependent, CT-independent secretion of IL-1β from THP-1 cells is induced by El Tor, but not classical, V. cholerae strains. THP-1 (gray bars) or ASCdef THP-1 (white bars) cells were treated at an MOI of 25 with wild-type V. cholerae El Tor strain P27459, N16961, or E7946; wild-type classical strain 9459 or O395; or ΔctxAB mutant P4 (derived from P27459) or E4 (derived from E7946). (A to C) Supernatant fluid from cells treated with bacteria for 3 h were collected and assayed for IL-1β by ELISA. (D) CT secretion into RPMI culture medium was measured by ELISA after 3 h of growth. Data are presented as the mean ± the standard deviation of triplicate samples. *, P < 0.05; <d. l., below the detection limit.