Secretory component of the guinea-pig.

Free secretory component (FSC) was purified from guinea-pig milk by gel-filtration and immunoabsorption on anti-SC antibodies. Guinea-pig FSC cross-reacted with antisera to human FSC, and the reverse. Guinea-pig and human FSC resembled each other in molecular size, electrophoretic mobility and heterogeneity, as well as by the existence of antigenic determinants restricted to the unassociated form of the molecule. Guinea-pig FSC associates in vitro with guinea-pig IgM. Distribution of disulphide links is required to set free guinea-pig FSC from secretory IgA.