Bile immunoglobulin of the duck (Anas platyrhynchos). I. Preliminary characterization and ontogeny

Immunoglobulin (Ig) of a single class was found in duck (Anas platyrhynchos) bile. Its molecular weight was 890,000; serum IgM was 800,000. Heavy chains were 75,000 for bile Ig, 86,000 for IgM, 67,000 for 7.8S IgG and 37,000 for 5.7S IgG. Antigenic comparison showed that bile Ig resembled IgM but carried additional determinants. The ontogeny of bile Ig was distinct from that of serum IgM and IgG. Thus, duck bile Ig appears to be an IgM-like molecule secreted independently of serum Ig.