The induction of oral tolerance to Actinomyces viscosus in mice.
OBJECTIVE
To determine whether oral tolerance with the oral bacterium Actinomyces viscosus was inducible in mice.


METHODS
Mice were intragastrically (i.g.) and then intraperitoneally (i.p.) immunized with heat-killed A. viscosus. A control group of mice received only saline. A delayed type hypersensitivity (DTH) response and the levels of isotype specific antibodies were assessed. Spleen cells from mice that were i.g. immunized with A. viscosus were transferred to A. viscosus-primed mice in vivo and in vitro. Furthermore, mice were i.g. immunized with saline or A. viscosus and then challenged i.p. with saline, A. viscosus, or Porphyromonas gingivalis.


RESULTS
Intragastric immunization with A. viscosus suppressed both DTH and serum specific antibodies to A. viscosus. DTH suppression lasted until week 4, while serum immunoglobulin (Ig)A and both IgG and IgM specific antibody levels remained suppressed up to week 8 and 12 respectively. IgG specific antibody suppression was transferable. The DTH response and serum antibodies specific to A. viscosus were suppressed in mice after i.g. challenged with A. viscosus but not P. gingivalis.


CONCLUSIONS
Mucosal presentation of A. viscosus in mice led to the suppression of immune response to this bacterium in an antigen-specific fashion. Tolerance of DTH response was short lived, while suppression of antigen-specific IgG antibodies in mucosally tolerized mice was long-lasting.
Sosroseno
W
W
Department of Oral Biology, School of Dental Sciences, Universiti Sains Malaysia, Kota Bharu, Malaysia. wihaskoro@kb.usm.my
Bird
P S
PS
Gemmell
E
E
Seymour
G J
GJ
D016924:Actinomyces viscosus / Q000276:immunology*; D019264:Adoptive Transfer; D000704:Analysis of Variance; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000917:Antibody Formation; D000939:Epitopes; D005260:Female; D006968:Hypersensitivity, Delayed / Q000276:immunology; D007108:Immune Tolerance; D007114:Immunization; D051379:Mice; D008811:Mice, Inbred DBA; D009061:Mouth Mucosa / Q000382:microbiology*
D000907:Antibodies, Bacterial; D000939:Epitopes