Molecular Restriction of Anti-DNP Antibodies Induced by Dinitrophenylated Type III Pneumococcus

Abstract

Abstract Rabbits were hyperimmunized with ε-DNP-lysine covalently coupled to type III encapsulated pneumococci (DNP-Pn vaccine). After a preimmunization with pneumococcal vaccine followed by immunization with DNP-Pn vaccine, 11 of 13 rabbits produced anti-DNP antibodies with titers ranging from 0.28 to 1.30 mg/ml. The affinities of the anti-DNP antibodies were low (105 liters/mole). The molecular heterogeneity of 7 of the 11 responding rabbits, as determined by isoelectric focusing, was markedly reduced. Upon continued immunization some rabbits maintained or increased their restriction while others exhibited a loss of restriction and evidence of molecular heterogeneity. Although titers and heterogeneity generally increased during prolonged immunization, association constants for the anti-DNP antibodies remained in the range of 105 liters/mole. The present experiments indicate that a bacterial carrier can have a marked effect on the structural complexity of anti-DNP antibodies and provide a new means of obtaining structurally restricted anti-hapten antibodies.