“…Purified PT was generously provided by Dr. Witold Cieplak (RIBI Immunochem, Hamilton, MT). The material utilized in these studies was purified from culture filtrates of Bordetella pertussis strain 3779 Bl 2 S 4 using Affi-Gel Blue (Bio-Rad, Hercules, CA) followed by affinity chromatography using fetuin as previously described [50]. The purified PT was maintained at a concentration of 180 g/ mL in 0.1M Tris, 0.5M NaCl, pH 8.0, and was diluted from this stock immediately prior to each experiment.…”