Isolation of porcine secretory immunoglobulin A by affinity chromatography and determination of its component chains.

Porcine secretory immunoglobulin A (SIgA) was isolated in a single step from porcine milk whey by affinity chromatography, using antiporcine alpha-chain specific antibody linked to CNBr-activated agarose. The isolated SIgA contained no other proteins detectable by immunodiffusion of immunoelectrophoresis. After reduction and alkylation with dithiothreitol and iodoacetamide, the SIgA was chromatographed on gel equilibrated with 6.0 M urea and 1.0 M propionic acid. Polyacrylamide gel electrohoresis of the fractions eluted revealed the presence of light chain, alpha-chain secretory component, and J-chain.