Antigenic difference between serum amyloid protein SSA and its low molecular weight derivative SAAL revealed by an...

Serum amyloid protein SAA and its low molecular weight derivate SAAL have been compared in immunodiffusion with an antiserum to amyloid A at different temperatures. At room temperature or at 37 degree C SAAL and SAA did precipitate with anti-AA forming a line of identity. At 4 degrees C, however, only SAAL did react with anti AA. Experiments are described which show that the SAA-derivative SAAL has AA-related antigenic determinants exposed whereas these determinants are hidden in the parent SAA and are only exhibited as result of an unknown temperature-dependent process. Therefore, SAAL can also be distinguished from SAA by the availability of AA-related antigenic determinants for anti-AA antibodies at 4 degrees C.