THE RANGE AND FINE SPECIFICITY OF THE ANTI‐HAPTEN IMMUNE RESPONSE: PHYLOGENETIC STUDIES

Abstract

Heterodontus francisci (horned shark) and Pseudopleuronectes americanus (winter flounder) were immunized with furyl-oxazolone (furyl-Ox) and phenyl-oxazolone (phenyl-Ox) coupled either to bacteria or protein carriers. The antibodies produced were measured by inactivation of furyl- or phenyl-Ox conjugated bacteriophage, and their affinity and fine specificity were estimated by inhibition of phage inactivation with a series of structurally related hapten analogs. In both species, post-immunization peak titers were 100-2000 times higher than preimmunization titers. A number of unique features distinguished Heterodontus antibodies from Pseudopleuronectes or mammalian antibodies. Heterodontus antibodies exhibited a lower affinity for the immunizing hapten (furyl-Ox or phenyl-Ox) and a reduced ability to distinguish the homologous immunogenic hapten from its structural analogs. Heterodontus antibodies exhibited a lower level of interindividual variation in affinity and fine specificity than did Pseudopleuronectes or mammalian IgM antibodies; this was especially prominent in anti-furyl-Ox responses. Typically the affinity and fine specificity of Heterodontus antibodies did not change over the 146 day period of immunization and were not influenced by the nature of the carrier. The implications of these findings in terms of the phylogenetic origins of antibody diversity are discussed.