Binding of canine IgM and IgG to protein A of Staphylococcus aureus: a simple method for the isolation of canine immunoglobulins from serum and the lymphocyte surface.

The binding of normal canine serum IgG and IgM to staphylococcal protein A is described. Virtually all (greater than 99%) of IgG and up to 90% of IgM could be removed from canine serum, utilizing this phenomenon. The nature of the bound material was confirmed by immunodiffusion in agar, radioimmunoassay, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Attempts to elute differentially IgG and IgM from protein A-Sepharose columns, using gradients of pH or the chaotropic agent sodium thiocyanate, were unsuccessful. This phenomenon provides a basis for the isolation of canine IgM from serum. Lymphocyte surface IgM, studied by lactoperoxidase-catalyzed membrane radioiodination and solubilization in nonionic detergent, also showed the property of binding to staphylococcal protein A.