Gerbil interleukin-18 and caspase-1: cloning, expression and characterization.

We are reporting the molecular cloning of gerbil interleukin-18 (IL-18) and caspase-1. The cDNAs encoding the molecules were cloned by cross-species reverse transcriptase-polymerase chain reaction (RT-PCR) and 5'/3' rapid amplification of cDNA ends (RACE). COS-7 cells transfected with plasmids encoding pro-IL-18 and caspase-1 precursor expressed the two proteins intracellularly. When the cells were lysed in the presence of dithiothreitol, caspase-1 precursor became active and converted pro-IL-18 into mature IL-18. A partially purified preparation of gerbil mature IL-18 was bioactive, as it stimulated the proliferation of gerbil spleen cells in a dose-dependent manner.