MOUSE SERUM-AMYLOID-A (SAA) PROTEINS ISOLATED BY 2-DIMENSIONAL ELECTROPHORESIS - CHARACTERIZATION OF ISOTYPES AND THE EFFECT OF SEPARATE AND COMBINED ADMINISTRATIONS OF CYTOKINES, DEXAMETHASONE AND LIPOPOLYSACCHARIDE (LPS) ON SERUM LEVELS AND ISOTYPE DISTRIBUTION

Hydrophobic interaction chromatography and two-dimensional electrophor esis were used to isolate and characterize mouse SAA, and to study the in vivo effect of separate or combined administrations of cytokines, dexamethasone (DEX) and LPS on mouse SAA. Four SAA spots containing pa rtial amino acid sequence in accordance with mouse apoSAA1 and apoSAA2 /SAA(SJL/J) pi 5.9 were demonstrated in serum. One of these proteins r epresents a previously undescribed, acidic acute-phase mouse SAA prote in. Both DEX and interferon-gamma (IFN-gamma) proved to be capable of increasing SAA serum levels. In contrast to what has been shown in pre vious in vivo studies, administration of IL-6 did increase the SAA lev els to nearly the same magnitude as IL-1, and the effect of IL-6 and L PS on SAA production was not significantly altered by the addition of DEX. Irrespective of the inflammatory stimuli that was administered, a non-selective production of SAA1 and SAA2 was observed in most groups , including the group that received IL-6. The results illustrate that data obtained about mouse SAA are highly dependent on which models, is olation and identification methods are used.