Adjuvant Principle of Pertussis Vaccine in the Mouse

IT is well known that the vaccines of many Gram-negative bacteria greatly enhance the antibody response to unrelated antigens administered to animals at about the same time, or as combined immunizing agents. The most familiar example is the increased potency of diphtheria and tetanus toxoids when combined with pertussis vaccine. Many investigators have attributed this heightened response to the heat-stable lipopolysaccharide endotoxins of this class of bacteria. Farthing 1 tested the effect of heating pertussis vaccine for 1 h at 100° C on its ability to enhance antibody response to diphtheria toxoid in guinea-pigs. He found no effect which he could ascribe to heat, and went on to show that extracted endotoxin was responsible for the increase in antibody titre.