Lack of Significant Differences in Association Rates and Affinities of Antibodies from Short-Term and Long-Term Responses to Hen Egg Lysozyme

The affinities ( K a) and association rate constants ( k on) of 23 mouse (BALB/c) anti-lysozyme mAbs obtained after short and prolonged immunizations have been measured by plasmon resonance techniques. The affinities for the 23 Abs, measured using their Fab, range from K a = 1.1 × 107 to 1.4 × 1010 M−1. There is no significant correlation between time or dose of immunization and affinity or association rates, indicating no time- or dose-dependent maturation of the response within the doses and times that were explored. IgMs are produced early and late in the response, with intrinsic affinities <105 M−1. Two independently derived mAbs, D44.1 (short term) and F10.6.6 (from a longer term response), result from identical or nearly identical somatic recombination events of germline gene segments. F10.6.6 has more mutations and a higher affinity constant ( K a = 1.4 × 1010 M−1) than D44.1 ( K a = 1.1 × 107 M−1). Although higher affinities may result from an accumulation of mutations, they do not correlate with the length and dose of immunogenic challenge.