The primary and secondary cellular immune responses to whole cell Bordetella pertussis vaccine and its components

The cellular immune responses of Balb/c mice and Wistar rats immunized in hind footpads with intact killed Bordetella pertussis were found to differ from those of similar animals immunized with other bacteria including Bordetella bronchiseptica, Salmonella typhimurium and Escherichia coli. All the bacteria stimulated increases in cell number, proliferation and interleukin 2 (IL-2) production in popliteal lymph nodes which peaked 3-5 days after injection and decreased to resting levels by day 7. However, B. pertussis also caused a second peak in all three parameters at 11 days after immunization. This peak was not seen following injection with any of the other bacteria. Bordetella pertussis also caused systemic effects, increased cellular proliferation in bone marrow and thymus, with similar biphasic kinetics. It possesses a potent toxin, distinguishing it from the closely related B. bronchiseptica. The use of purified materials confirmed that the presence of this pertussis toxin (PT) was responsible for the later peak in stimulation, whereas lipopolysaccharide (LPS) in combination with PT and also the filamentous haemagglutinin (FHA) could mimic the early peak of stimulation. Primary immunization with B. pertussis was also shown to generate lymph node cells which responded in vitro to secondary challenge with B. pertussis cells, FHA or PT. Both proliferation and IL-2 production were enhanced, except with FHA which only increased IL-2 production. Lymph node cells from mice immunized with E. coli showed no such responses.