FIG 4.

In vitro neutralization of cytotoxins with rabbit sera after passive immunization with human MAbs. Rabbit sera, collected at 1 h before bacterial challenge from animals treated with Hla-F#5, Hla-specific, or control MAbs, were pooled and tested for cytotoxin neutralization potency using rabbit cells. (A) Rabbit red blood cell (RBC) hemolysis inhibition assay using Hla at 10 nM. (B to D) Rabbit PMN lysis inhibition assay using LukSF-PV at 1 nM (B), LukED at 0.1 nM (C), and HlgCB at 0.25 nM (D). Error bars represent SEM of data from at least 2 independent experiments for each toxin.