The nature of antibodies to goat erythrocytes in the developing chicken.

The maturation of the immune response to goat erythrocytes in chicken from hatching onwards is described. Agglutinins in immune sera were examined for their sedimentation properties, heat stability at 65°, resistance to 2-mercaptoethanol (ME) and ability to agglutinate at 4° or 37°. Large doses of goat erythrocytes were given to favour the induction of the IgG response. Agglutinins were tentatively classified as class I, which were cold and warm agglutinins, IgM, ME-susceptible and heat-labile; class II, a warm agglutinin, IgG, ME-resistant and only slightly heat-labile; and class III, a cold agglutinin, possibly IgA, partially resistant to ME but completely heat stable. Immune agglutinin was first detected in sera from 11-day-old chicks and all three types were detectable at 17 days of age. Multiple injections of goat erythrocytes induced an earlier response than single injections. Agglutination titres, in response to weight-adjusted doses of antigen, increased from 5 to 24 weeks of age. Chicks could be made hyperimmune by 6 weeks of age when the proportion of class II antibody was much increased compared to that in primary sera.