Murine responses to immunization with pertussis toxin and bovine serum albumin: I. Mortality observed after bovine albumin challenge is due to an anaphylactic reaction.

It has been suggested that pertussis toxin (Ptx) is involved in the pathogenesis of the adverse neurologic reactions that can occur in infants and children after pertussis immunization. One group of investigators has recently reported that a clinical syndrome with pathological features very similar to post-pertussis vaccination encephalopathy can be induced in specific strains of mice after their immunization with bovine serum albumin (BSA) and Ptx. The aim of this investigation was to further characterize the immunologic mechanisms operative in this murine model. Studies were undertaken to determine whether the role played by Ptx in this condition required the A-protomer of the toxin to enter a cell and ADP-ribosylate a nucleotide binding protein (a Class I activity) or was dependent upon the binding of the B-oligomer of the toxin to the surface of target cells (a Class II activity). The results of our experiments have established that the disease induced by coimmunizing mice with Ptx and BSA is due to an immediate type hypersensitivity reaction rather than an encephalopathy and that the mechanism of action of Ptx in this system seems to be dependent upon a Class II activity of the toxin and independent of its ADP-ribosyl transferase activity.