Effect of pertussigen on inflammation caused by Freund adjuvant

Pertussigen, one of the toxins from Bordetella pertussis, greatly increased the inflammatory response produced by complete Freund adjuvant in the footpads of mice. This effect was not produced by pertussigen when the emulsion was made with saline and incomplete Freund adjuvant, but if an antigen was included in incomplete Freund adjuvant, the strong potentiating effect was again demonstrated. As little as 100 ng of pertussigen given intravenously was effective, but 400 ng proved better, and this latter dose was used routinely. The most striking action occurred when pertussigen was injected on the same day or 3 days after complete Freund adjuvant, but an effect was demonstrated when given from 3 days before to 6 days after complete Freund adjuvant. The action of pertussigen was not apparent until about 6 to 8 days after complete Freund adjuvant. The footpad swelling reached its maximum by day 14 and remained undiminished until day 29. Forty days later, a significant effect was still present. Histologically, the cellular infiltrate in the feet of mice injected with complete Freund adjuvant was more intense in animal treated with pertussigen. Nude BALB/c mice receiving an emulsion of complete Freund adjuvant in the footpads did not respond with an increased inflammation after receiving pertussigen, suggesting the possible involvement of T cells in this phenomenon. The intense and prolonged inflammatory response produced in pertussigen-treated mice by Freund adjuvant containing antigenic substances may serve as a useful model to study chronic inflammation.