SERUM AMYLOID-A PROTEIN IN MINK DURING ENDOTOXIN-INDUCED INFLAMMATIONAND AMYLOIDOGENESIS

Two-dimensional electrophoresis was used to study SAA and AA proteins in mink during lipopoly-saccharide-induced inflammation and amyloidoge nesis. Three isotypes, SAA pI 6.8 and SAA pI 6.5 (both SAA1-like), and SAA pI 6.0 (SAA1- and SAA2-like), were identified in serum after both single and multiple LPS injections. Total SAA serum levels were highe st in the early phase of induction, followed by a decrease ranging fro m 1 to 50% of the peak value during the rest of the experiment. The va riation in the total SAA levels correlated with the total SAA mRNA lev els. Low total SAA levels were seen both in non-amyloidotic and amyloi dotic animals, and a general decrease of all isotypes was demonstrated . In hepatic amyloid fibrils, several AA isotypes, with amino acid seq uence homologous exclusively to that of SAA2, were found. In the corre sponding splenic material, fragments of histones H2A and H2B constitut ed most of the low molecular mass proteins, and no protein AA was dete cted. In spite of low serum levels and a non-specific isotype removal, the results confirm that SAA2 is amyloidogenic in mink.