Mutant Escherichia coli enterotoxin as a mucosal adjuvant induces specific Th1 responses of CD4+ and CD8+ T cells to nasal killed-bacillus calmette-guerin in mice.

On single nasal immunization of mice with killed-bacillus calmette-guerin (BCG) plus a mutant Escherichia coli enterotoxin, delayed-type hypersensitivity was induced and BCG-infection decreased. Spleen cells, particularly CD4+ T cells among them produced IL-2, IFNgamma and TNFalpha in response to the killed-BCG or purified protein derivatives. CD8+ T cells including cytotoxic T lymphocytes produced IFNgamma and TNFalpha. However, both types of T cells reacted a little to Ag85B. The mutant induces cellular immunity to nasal killed-BCG vaccine and decreases BCG-infection. CD4+ and CD8+ T cells produce cytokines effective for tuberculosis. Although killed-BCG loses some antigens like Ag85B, nasal killed-BCG plus the mutant is useful for tuberculosis.