Abstract
Forty % of serum IgM and 47 % of dimeric colostral IgA were bound to protein A-Sepharose. Fab μ and Fabα fragments showed a reactivity similar to that of the whole immunoglobulins. Complete elutions of IgM and IgA from the protein A-Sepharose were obtained in lower concentrations of MgCl2 than the complete elution of IgG. However, IgM and IgA were completely eluted at higher concentrations of MgCl2 in the presence of IgG than in its absence.