Figure 4.
Correlation between affinity and potency of toxin cross-neutralizing mAbs. (A): Neutralization potency of toxin cross-reactive mAbs Hla-F#1-7 was determined with rabbit RBCs for Hla, and with freshly isolated human PMNs for HlgCB, LukED and LukSF and expressed as mAb:toxin ratio at half maximal inhibition of cell lysis (IC50). For all toxins the correlation between in vitro potency and affinity was significant based on Pearson's correlation coefficient analysis (r > 0.9, P < 0.005). In vivo potency of mAbs was determined in intravenous challenge of mice with HlgAB (B) and HlgA-LukD (C) or with intranasal challenge with Hla (D). Groups of 5 mice were given 100 μg of indicated mAbs intraperitoneally before challenge with 100% lethal dose of toxins. Fab affinities (KD) measured by MSD are indicated.