Actinobacillus actinomycetemcomitans possesses an antigen binding to anti-human IL-10 antibody

It is well known that the cell components of periodontopathic bacteria are able to induce several cytokines and possibly to affect the cytokine network. In order to determine the presence of the periodontopathic Actinobacillus actinomycetemcomitans components recognized by antibodies against cytokine molecules, ELISA reactivities of sonic extracts from the bacterial cells were determined by use of ELISA kits specific for human interleukin (IL)-1beta, IL-4, IL-5, IL-6, IL-10, tumor necrosis factor-alpha, and interferon-gamma. The ELISA analysis demonstrated that the sonic extracts from eight strains of A. actinomycetemcomitans bound with anti-human IL-10 monoclonal antibody. Western blotting analysis revealed that the molecular mass of the antigen was approximately 65 kDa. IL-10 is produced by type 2 helper T cells and mainly down-regulates the type 1 helper T cell response. The present study suggests that the 65-kDa antigen of A. actinomycetemcomitans may affect the host defense function through binding to IL-10 receptor as an agonist or an antagonist for IL-10.