Mice were immunized subcutaneously in the flanks on day zero with 50 μg NP-KLH (Biosearch Technologies) emulsified in 100 μl Imject Alum (ThermoScientific). Serum and draining inguinal lymph nodes for flow cytometric analysis were collected on day 12 post-immunization. Affinity assays were performed as described previously29 (link). Briefly, plates (Corning, New York, NY) were coated at with 10 μg/ml of either NP-27-BSA (total) or NP-2-BSA (high-affinity) per well (Biosearch Technologies). Antibody titers are given as –log2 dilution × 40. Positive titers were defined as three standard deviations (SD) above the mean values of the negative controls41 (link).