ICE inhibition prevents the generation of ICE-specific bands but not the release of IL-1β bioactivity.

(A) Cell lysates (cl, lanes 1 and 2) or supernatants (sups, lanes 3 and 4) from DCs challenged for 8 hours with allogenic T cells at a T-cell:DC ratio of 10:1, in the absence (−, lanes 1 and 3) or presence (+, lanes 2 and 4) of 100 μmol/L AcYVAD-CMK, were analyzed as for their content in pro–IL-1β or IL-1β by Western blot. (B) Bioactivity of secreted IL-1β: aliquots of different dilutions (as indicated) of supernatants of DCs cultured 8 hours alone (○) with alloreactive T cells in the absence (▪) or presence (□) of 100 μmol/L AcYVAD-CMK were added to HUVEC and incubated at 37°C for 20 hours. At the end of the incubation, the ICAM1 molecules expressed by HUVEC were quantified by ELISA.