Adjuvant for IgE antibody and islet-activating protein in Bordetella pertussis.

A new purified protein, with a molecular weight of 77,000, isolated from the supernatant of Bordetella pertussis culture fluid and called islet-activating protein (IAP), had adjuvant activity for IgE antibody in addition to leukocytosis-promoting, histamine-sensitizing and islet-activating activities. None of the three subunits (F1, F2 and F3) was biologically active by itself. All of the four activities were recovered in the complexes of subunits F1.3 and F2.3. These results suggest that the activities are brought about by a common factor inherent in B. pertussis.