Leukocytosis-promoting factor of Bordetella pertussis. II. Biological properties.

The leukocytosis-promoting factor (LPF), purified from materials extracted from agar in which Bordetella pertussis was grown, caused leukocytosis and an increased sensitivity to histamine when as little as 0.04 mug of protein was given intravenously to mice. LPF was adsorbed onto erythrocytes, causing hemagglutination. As little as 0.03 mug of LPF protein agglutinated chicken erythrocytes in 0.05 ml of a 0.5% suspension. The physicochemical, biological, and immunological properties indicated that leukocytosis, increased sensitivity to histamine in mice, and agglutination of erythrocytes are functions of a single substance.