Synthesis of pro–IL-1β by DCs is induced by maturative stimuli.

(A) Cell lysates (lanes 1 to 3, c) and supernatants (lanes 4 to 6, s) from DCs cultured for 6 days in the presence of GM-CSF and IL-4 followed by 40 hours with GM-CSF/IL-4 alone (−, lanes 1 and 4) or in the presence of LPS (lanes 2 and 5) or TNFα (lanes 3 and 6) were incubated for 8 hours in serum-free medium supplemented with 1% nutridoma. Lanes 7 and 8: cell lysates (c) and supernatants (s) from freshly isolated monocytes stimulated for 3 hours with LPS. Samples were analyzed by SDS-PAGE, followed by Western blotting with anti–IL-1β antibodies. (B) Cell lysates from DCs (lanes 1 to 3) or monocytes (lane 4) untreated (lane 1) or treated with LPS (lanes 2 and 4) or TNF-α (lane 3) as indicated. Blots were hybridized with anti ICE antibodies.