GENETIC-CONTROL OF IMMUNE-RESPONSES TO A SYNTHETIC FIMBRIAL ANTIGEN OF ACTINOBACILLUS-ACTINOMYCETEMCOMITANS

The incidence of infection by Actinobacillus actinomycetemcomitans, on e of the important pathogens in human periodontal diseases, has been r eported to be associated with racial background and genetic factors, W e attempted to determine the genetic regulation of immune responses to A. actinomycetemcomitans fimbriae, an attachment factor using various inbred strains of mice, For this purpose, we synthesized an oligopept ide antigen using the amino acid sequence of the fimbriae and conjugat ed this antigen to branched lysine polymer resin beads, After immuniza tion with the synthetic A. actinomycetemcomitans fimbrial antigen, ser um antibody levels and the delayed-type hypersensitivity (DTH) reactio n to the antigen were measured by enzyme-linked immunosorbent assay (E LISA) and footpad swelling responses, respectively, The strains of mic e found to be high-IgG responders to the antigen were B1O.HTT, B10.RII I, B10.A (5R) and B10.S (9R). These results indicate that mice with E- beta(5):E-alpha(k): E-beta(r):E-alpha(r) and E-beta(b):E-alpha(k) resp ond strongly to the synthetic peptide. All of the high-IgG responders showed a high DTH response. A cell transfer experiment confirmed that CD4 T cells mediated with a DTH response to the synthetic peptide, Thu s, the results of this study demonstrate that the immune responses to A. actinomycetemcomitans fimbriae are genetically controlled.