Leukocytosis-promoting factor of Bordetella pertussis.

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 Ag of protein was given intravenously to mice. LPF was adsorbed onto erythrocytes, causing hemagglutination. As little as 0.03 ,g 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.