Isolation of serum amyloid P-component (protein SAP) in the mouse

Serum amyloid P-component (protein SAP) was associated from mouse serum and ascitic fluids by calcium-dependent affinity chromatography on Sepharose 4B (Pharmacia) followed by gel filtration on Ultrogel AcA44 (LKB) in the presence of EDTA. It was homogenous on gradient polyacrylamide gel and sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis, and induced a monospecific antiserum in the rabbit. The related protein, C-reactive protein (CRP) was present in only trace amounts not exceeding 2 mug/ml of serum even during acute phase reactions. It was isolated by calcium-dependent affinity chromatography on insolubilized pneumococcal C-polysaccharide. The availability of these isolated mouse proteins and their respective antisera will facilitate investigation of their function.