IL1B and hydrops fetalis: HF dramatically decreased pro–IL-1β levels in the cell lysates, whereas the pro–caspase-1 levels were not affected by HF in LPS- and LPS plus HF–stimulated macrophages (Fig 1D, S2G Fig), indicating that HF affects IL-1β not only at the level of processing but also at the level of expression of pro–IL-1β.