Heterogeneous participation of the hepatocyte population in amyloid protein AA synthesis

Amyloid protein AA is believed to be synthesized in the liver in a form of its precursor, the acute phase reactant, SAA. To identify precisely the cell involved in SAA biosynthesis, immunohistochemical reaction to anti-mouse AA was analysed on the liver sections from CBA/J mice which had received a single casein injection and were sacrificed at predetermined times up to 48 hours. Two different primary localizations of the reaction were revealed. One was in the cytoplasm of certain hepatocytes. This reaction peaked at 6-8 hours after the casein injection in the intensity of the reaction and in the number of the cells involved. The hepatocytes with positive cytoplasmic reaction were scattered over the lobule and even at the peak did not exceed 20% of the total hepatocyte population. The other localization of the reaction covered linearly the surface of the hepatocyte cords, and peaked at 12-16 hours after the casein injection.