Effect of colchicine on the murine immune response induced by Aggregatibacter actinomycetemcomitans

The aim of the present study was to test the hypothesis that colchicine may alter Aggregatibacter actinomycetemcomitans-induced immune response and abscess formation in mice. BALB/c mice were either sham-immunized or immunized with heat-killed A. actinomycetemcomitans. Spleen cells were stimulated with heat-killed A. actinomycetemcomitans in the presence or absence of colchicine. Specific IgG subclass antibodies, interferon-γ (IFN-γ), interleukin-4 (IL-4) and cell proliferation were determined. The animals were sham-immunized (group I) or immunized with heat-killed A. actinomycetemcomitans (groups II–VII). Colchicine was administered intraperitoneally before (group III), on the same day of (group IV), or after (group V) the primary immunization and on the same day of (group VI) or after (group VII) the secondary immunization. All groups were challenged with viable A. actinomycetemcomitans. The levels of serum-specific IgG subclasses and both IFN-γ and IL-4 before and after bacterial challenge were assessed. The diameter of skin lesions was assessed. The results showed that colchicine augmented splenic-specific IgG1 and IL-4 as well as cell proliferation but suppressed specific IgG2a and IFN-γ levels. Enhancement of serum-specific IgG1 and IL-4 levels, suppression of specific IgG2a and IFN-γ levels as well as DTH response, and delayed healing of the lesions were observed in groups IV and VI, but not in the remaining groups of animals. Therefore, these results suggest that colchicine may induce a T helper 2 (Th2)-like immunity specific to A. actinomycetemcomitans in vitro and that colchicine administered on the same day as the immunization may stimulate a non-protective Th2-like immunity in A. actinomycetemcomitans-induced infections in mice.