Leucocytosis-promoting factor of Bordetella pertussis. I. Purification and characterization.

The leucocytosis-promoting factor was purified from the supernatant fluid of spent cultures of Bordetella pertussis on solid medium. After precipitation at 67% saturation of ammonium sulfate, the leucocytosis-promoting factor was extracted with a 1.0 m NaCl solution. Purification was accomplished by starch block electrophoresis and sucrose density gradient centrifugation. The purified preparation contained a high leucocytosis-promoting activity, and as small an amount as 0.04 mug of protein induced leucocytosis in mice. About 520-fold purification was attained, with a re-recovery of about 25% on an activity basis. The leucocytosis-promoting factor was composed solely of filamentous molecules of about 2 by 40 nm in size, with a sedimentation coefficient of approximately 5.5S and a molecular weight of 108,000. It was insoluble in water but partially soluble in 1.0 m NaCl solution, and consisted mainly of protein, with some carbohydrate, lipid, and phosphorus.