Identification of two transcripts of canine, feline, and porcine interleukin-1 alpha

Reverse transcription-polymerase chain reaction (RT-PCR) with interleukin-1 alpha (IL-1 alpha)-specific primers using total RNA from lipopolysaccharide (LPS)-stimulated lung macrophages resulted in the amplification of two dis tinct cDNA fragments. Cloning and sequencing of the canine and feline fragm ents revealed that, except for the absence of a specific 174 nucleotide seq uence, the short and the long transcripts were identical. The in-frame 174 nucleotide deletion corresponds to exon 5 of the human and murine IL-1 alph a gene, which encodes the cleavage site for calpain, a protein necessary fo r the processing of the IL-1 alpha precursor into mature IL-1 alpha. The tw o transcripts were found in the dog, cat and pig; analysis by RT-PCR, South ern and Northern blot hybridization showed no expression of the shorter IL- 1 alpha mRNA in equine or bovine macrophages. Expression of the two canine IL-1 alpha transcripts was also detected in synovial membranes and was coor dinately up-regulated in response to Borrelia burgdorferi infection under b oth in-vitro and in-vivo conditions. (C) 1999 Elsevier Science B.V. All rig hts reserved.