Characterization of a novel monoclonal antibody which identifies chicken secretory component

A mouse monoclonal antibody (MAb) produced against chicken biliary IgA (bIgA) was characterized. This MAb, designated A63, reacted with purified chicken biliary IgA (bIgA) but not with serum IgA in ELISA. In Western blot analysis, it recognized an 80-kDa protein associated with bIgA. MAb A63, but not a chicken IgA-specific MAb, reacted strongly with chicken embryo allantoic fluid, a rich source of SC, in immunoblots. In immunohistostained sections of chicken intestines A63 stained intracytoplasmic vacuoles in the enterocytes consistent with goblet cells, whereas the IgA-specific MAb predominantly stained plasma cells in the lamina propria. Whereas the IgA-specific MAb only reacted with the homologous IgA, MAb A63 reacted with bile samples of chicken, turkey, and quail but not of duck or pheasant. These data collectively indicated that MAb A63 recognized an avian secretory component (sc).