Investigation in a model system of the effects of combinations of anthrax and pertussis vaccines administered to service personnel in the 1991 Gulf War.

The toxicity and immunogenicity of the anthrax and pertussis vaccine combinations used in the 1991 Gulf War was assessed in NIH, A/J and Balb/c mice. Inoculation of pertussis vaccines, vaccine combinations, or aluminium salt caused illness, splenomegaly and significant weight loss. Although some animals recovered eventually, a lethal form of ascites developed in some NIH mice and body weights of A/J and Balb/c mice remained below normal levels. Inoculation of anthrax vaccine produced little effect. Exposure to diluted vaccine combinations produced less serious side effects of shorter duration. Single vaccinations induced specific IgG1 antibodies whereas a mixture of IgG1 and IgG2a was produced after multiple injections. Antigen stimulation of spleen cells from mice exposed to pertussis vaccines induced high levels of NO and IL-6, whereas stimulated spleen cells from mice exposed to anthrax vaccine produced only low levels of IL-6. In mice, pertussis vaccines act as an adjuvant for anthrax vaccine, but these vaccines are also the major cause of toxicity of the vaccine combination. The relatively high vaccine dose used, together with the low sensitivity of mice to anthrax toxin, emphasises that caution should be exercised in applying these results to human recipients of these vaccines.