The differential dynamics of antibody subpopulation expression during affinity maturation in a teleost

A compositional analysis of the antibody response in rainbow trout was conducted using an affinity-based immunopartitioning assay. Trout were immunized with TNP-keyhole limpet hemocyanin (TNP-KLH) and individual serum titers and their affinity distributions analyzed over a period of 27 weeks. The kinetics of antibody affinity subpopulation development revealed certain key features: 1) the lowest affinity subpopulation (log aK, 3.5–3.99) appears early, does not achieve high titer, and was more transient than the higher affinity subpopulations; 2) intermediate affinity subpopulations (log aK, 5.0–5.99) appear later (week 5), achieve relatively high titers and persist longer; and 3) the highest affinity subpopulations (log aK, 6.0–7.49) emerge much later (post week 15), and have comparable titers to the intermediate affinity group. We find that the affinity maturation of the serum antibody response can be resolved into each affinity subpopulation’s contribution both in quantity and timing.