Analysis of the serum antibody responses to type 1 and type 2 fimbriae in mice immunized with Actinomyces viscosus T14V

Induction of mucosal and serum immune responses to a specific antigen of periodontal bacteria

The dynamics of the host immune response to periodontal bacteria not only may be informative from the standpoint of specific mucosal protection to these pathogens, but also may reveal the capacity of the mucosal immune response to provide protection of the host. To this end, we have examined the immune response to chromatographically purified fimbriae of P. gingivalis administered orally or systemically with liposomes and adjuvant in BALB/c mice, high responders to this antigen. Oral administration of P. gingivalis fimbriae clearly enhanced the fimbriae-specific salivary IgA response. ELISPOT analysis revealed that significant numbers of fimbriae-specific IgA SFC were seen in lamina propria and mesenteric lymph nodes but not in Peyer's patches of mice immunized orally. In contrast, antigen-specific IgM and IgG SFC were seen mainly in the circulating blood mononuclear cells. On the other hand, subcutaneous injection of fimbriae with GM-53 also raised the fimbriae-specific IgG followed by IgM and IgA responses in serum, and both IgA and IgG responses in saliva. Oral immunization was less effective than subcutaneous injection in terms of the serum antibody response. However, the salivary antibody level of mice injected subcutaneously was similar to that of mice immunized orally. In the subcutaneously immunized mice, fimbriae-specific SFC were detected in the spleen, blood, and brachial lymph nodes by ELISPOT assay. Fimbriae-specific IgM SFC appeared earlier and antigen-specific IgG SFC were seen later. These results show that the combined use of fimbriae together with the adjuvant results in sharply increased IgA responses in saliva and IgG responses in serum. In summary, it is clear that the nature of the host's antibody response in serum and mucosal secretions is distinct, and depends on the route of antigen administration, the use of adjuvant and/or liposomes, and the temporal phase of the humoral immune response following various immunization regimes.

Genetic control of serum antibody responses of inbred mice to type 1 and type 2 fimbriae from Actinomyces viscosus T14V

Antibodies reactive with type 1 and type 2 fimbriae from Actinomyces viscosus T14V specifically inhibit the adherence of A. viscosus T14V to salivary pellicle-coated tooth surfaces and other bacteria, and these antibodies are thought to modulate colonization by this microorganism. These studies were done to determine whether previously noted differences in the antibody responses of inbred mice to type 1 and type 2 fimbriae might be under genetic control. The serum immunoglobulin G (IgG) and IgM antibody responses of inbred, F1 hybrid, and H-2 congenic mice, immunized with A. viscosus T14V cells, were analyzed by enzyme-linked immunosorbent assays for antibodies reactive with A. viscosus T14V whole-cell type 1 and type 2 fimbriae. The results confirmed earlier findings and indicated striking variations in the amounts of IgG anti-type 1 (23-fold) and anti-type 2 (48-fold) fimbria antibodies elicited. The responses of the 17 inbred strains tested showed a relatively continuous distribution from high to low, as well as marked differences in the responses of H-2 and Igh-C identical strain pairs. An analysis of the responses of F1 hybrid and H-2 congenic mice indicated dominance of the low-responder gene(s) and control by H-2-linked genes. Antisera from two high-responder strains inhibited in vitro bacterial adherence to a much greater degree than antisera from a low-responding strain. These data suggest polygenic control of the magnitude of the IgG anti-type 1 and anti-type 2 fimbria antibody responses by H-2-linked genes as well as background genes not associated with H-2 or Igh-C loci.

Serum antibodies to pathogenic actinomycetes in the normal human population

Sera of persons without known actinomycotic infection (n = 153) were tested for antibodies reacting with antigenic preparations of different Actinomyces spp. and Nocardia spp. By using an enzyme immunoassay, 16% of all of the sera analyzed reacted significantly with antigens of A. viscosus and 2% those of with A. naeslundii. The antigens detected by these antibodies were of low molecular mass (14-32 kDa) and showed a uniform reaction pattern in the immunoblot analysis. Multiple bands coccurred with a difference of approximately 2 kDa in size suggesting the presence of repetitive units. Analogous antibodies were not observed with A. israelii serovar 1 and serovar 2 antigens, which were only insignificantly bound by the sera. The antibodies demonstrated were most probably acquired during episodes of periodontal disease or gingivitis in which A. viscosus is etiologically involved. Antibodies against nocardial antigens were not demonstrated in significant proportions by enzyme immunoassay and immunoblot analysis.