Inhibition of caspase-1 activity by a reversible (YVAD-CHO) and an irreversible (YVAD-CMK) caspase-1 inhibitor measured in lysates of DH-VD3–pretreated THP-1 cells. DH-VD3–pretreated THP-1 cells were stimulated with 100 ng/mL of S minnesota Re 595 LPS as indicated. Cell lysates were prepared and caspase-1 activity was assessed 18 hours after stimulation as described in the Materials and Methods. The inhibitors were added in vitro to the lysates 5 minutes before measurement of caspase-1 before adding YVAD-AMC. (A) Results obtained with the reversible caspase-1 inhibitor YVAD-CHO. (B) Results obtained with the irreversible caspase-1 inhibitor YVAD-CMK. Shown are mean values of three independent experiments ± SD. Differences in (A) were significant with .01 < P < .02 and in (B) with .01 <P < .05, respectively. (□) Without LPS; (▪) with LPS.
