The mycobacterial component of complete Freund's adjuvant induces expulsion of the intestinal nematode Trichinella spiralis in mice.

Expulsion of T. spiralis adult worms was accelerated in high-responder NIH mice vaccinated previously with complete Freund's adjuvant (CFA) emulsified in PBS, whereas the expulsion of this parasite from low-responder C57 BL/10 mice was unaffected. Incomplete Freund's adjuvant (IFA) did not induce protection and it was concluded that the mycobacterial component, present in CFA but absent from IFA, was responsible for inducing these non-specific protective effects. CFA did not induce T. spiralis-specific B- or T-cell responses, but high levels of IFN gamma from Con A-stimulated mesenteric lymph node cells of CFA-vaccinated NIH mice were detected. Such cytokine release was not produced by cells from the C57 BL/10 strain. It is therefore proposed that IFN gamma production is related to the mode of adjuvanticity and non-specific protective effects of CFA in this system.