Molecular cloning of porcine interleukin-1β converting enzyme and differential gene expression of IL-1β converting enzyme, IL-1β, and IL-18 in porcine alveolar macrophages

We have cloned and sequenced a cDNA that contains the coding sequence of porcine interleukin-1 beta (IL-1 beta) converting enzyme (ICE), Using degenerate oligonucleotide primers based on the amino acid sequences of the human, murine, and rat ICE, we performed the reverse transcription polymerase chain reaction (RT-PCR) with total RNA prepared from porcine alveolar macrophages stimulated with lipopolysaccharide (LPS) to clone the cDNA of porcine ICE. The open reading frame (ORF) of the porcine ICE cDNA is 1215 base pairs (bp) in length and encodes 404 amino acids. The predicted amino acid sequence is 72.5%, 62.6%, and 64.1% homologous to the human, murine, and rat amino acid sequences, respectively. The kinetics of mRNA expression of ICE, IL-1 beta, and IL-18 in porcine alveolar macrophages after LPS stimulation revealed that ICE transcripts were weakly expressed in nonstimulated condition and upregulated after LPS stimulation. Moreover, IL-1 beta and IL-18 transcripts were differently expressed after LPS stimulation.