Page 1482 - Veterinary Immunology, 10th Edition

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FIG. 43.12 The structure of IgY and IgY(ΔFc) compared with
mammalian IgG.

The truncated isoform of IgY is produced as a result of alternative
splicing of heavy chain mRNA. Its correct name is therefore

IgY(ΔFc). Because it lacks an Fc region, it cannot activate
complement nor bind to Fc receptors. Its function is unclear. There
has, however, been a tendency during evolution to make low-
molecular-weight immunoglobulins. Similar truncated
immunoglobulins have also been described in some fish and turtles.

Evidence from mallards (Anas platyrhynchos) suggests that the ratio
of IgY(ΔFc) to intact IgY affects the efficiency of phagocytosis and
determines whether immune complexes are phagocytosed in the

spleen or liver.
Both isoforms of IgY lack a hinge. As a result, these molecules are
somewhat inflexible and only cause precipitation or agglutination

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