DIFFERENTIAL EXPRESSION OF RABBIT SERUM AMYLOID-A GENES IN RESPONSE TO VARIOUS INFLAMMATORY AGENTS

Serum amyloid A (SAA) is an acute-phase plasma protein which increases up to 1000-fold after an acute-phase stimulus. Several SAA genes and corresponding protein isotypes exist in individual species. Liver is t he main source of production, but extra-hepatic SAA expression has bee n described. In this study inflammation was induced in rabbits with li popolysaccharide, turpentine, or casein. Transcription of SAA mRNA was studied using Northern blot analysis with probes specific for three d ifferent rabbit SAA isotypes and analysed by scanning densitometry. In the stimulated liver slight variation in SAA mRNA transcription level was seen after stimulation with different inflammatory agents. After lipopolysaccharide-stimulation SAA gene expression was also seen in mo st of the extra-hepatic organs. After turpentine stimulation SAA mRNA was seen in the liver, the ovary, and the small intestines, and after casein stimulation only in the liver and the ovary. SAA1 and SAA2 were induced exclusively in the liver, while SAA3 was induced mainly in th e extra-hepatic organs. This indicates that the SAA genes probably are independently regulated both in relation to stimulus, gene- and tissu e-specificity.