A possible homologue of mammalian IgA in chicken serum and secretions.

Chicken serum was shown to contain a minor immunoglobulin component of β mobility, distinct from IgM and IgG. Its immunoglobulin nature was demonstrated by its reaction with antisera recognizing chicken light chains as well as by its antibody activity against ferritin in immunized animals. It was found to be the major immunoglobulin component in chicken bile and to be present in intestinal secretions. It is suggested to be the avian homologue of mammalian IgA, and pending confirmation of this hypothesis, it is provisionally termed `Iga'.