Immunomodulation by Proteins of Bordetella Pertussis

A selected number of immunobiologically active polypeptides have been found to be closely associated with, but separable from the lipopolysaccharide endotoxin LPS in the outer membrane of Gram-negative bacteria. Initially these endotoxin associated proteins EP from Bordetella pertussis, Salmonella typhi and Vibrio cholerae were found to enhance the immune response to cholera enterotoxin after immunization with cholera toxiod. At the cellular level, B. pertussis EP PEP is a mitogen and polyclonal activator of antibody producing B-lymphocytes of C3HHeJ mouse lymphocytes which are unresponsive to LPS. PEP can adjuvant in vitro the production of IgM antibody to cholera toxin and sheep erythrocytes by mouse splenic lymphocytes. In control experiments we have shown that the activity of PEP cannot be neutralized by the cationic polypeptide polymyxin B which specifically neutralizes the lipid A component of LPS that is responsible for the simulating properties of LPS. In addition, our tests indicate PEP does not contain any detectable lymphocytosis promoting factor LPF activity. Preliminary experiments have shown that extracts of B. pertussis which contain both LPS and associated proteins are protective in the standard mouse model used for testing the efficacy pertussis vaccines.