Evolution of low molecular weight immunoglobulins. V. Degree of antigenic relationship between the 7S immunoglobulins of mammals, birds, and lower vertebrates to the turkey IgY.

There are close antigenic relations between the turkey IgY--the dominant 7S Ig of serum--and the corresponding IgY-like Igs of chicken, duck, goose, tortoise, and frog as well as serum or colostral IgA of man and swine. The RIA-systems used for the determination of immunological cross-reactivity among the Ig types consisted of 125-I-labelled turkey IgY and class-specific rabbit anti-turkey IgY antibodies. The results stand in a good agreement with our findings demonstrating strong antigenic relationships between various serum or colostral Igs of IgY and IgA types, respectively, to the chicken IgY. Therefore, the IgY-like Igs seem to be the precursors for the IgA class of mammals.