It is the purpose of this project to study the biological effects of substances from Bordetella pertussis with special emphasis on those substances which induce physiological and immunological responses in experimental animals. Areas of current investigation are: (1) characterization of a highly purified crystalline pertussigen, obtained from B. pertussis, with respect to its ability to induce anaphylaxis, enhance vascular permeability, and produce long lasting histamine hypersensitivity in mice; (2) studies on the ability of pertussigen to enhance the development of acute experimental allergic encephalomyelitis in Lewis rats; and (3) studies on the peptides which occur in the plasma of pertussigen-treated Lewis rats following splanchnic ischemia.