Analysis of the genetic control of antibody response to Actinobacillus actinomycetemcomitans by immunoblotting inbred strains of mice.

Genetic regulation of the immune response may be involved in the onset and progression of an early-onset type of periodontitis. We analyzed the genetic control of the primary antibody response to Actinobacillus actinomycetemcomitans in inbred strains of mice using an immunoblot technique. Mice of 5 independent inbred strains, 6 H-2 congenic strains and 4 B10 intra-H-2 recombinant strains were immunized with sonicated extracts of A. actinomycetemcomitans. On the seventh day their sera were examined for reactivity to the antigenic components of this organism. Western blot analysis clearly distinguished 2 different groups of antigens, one consisting of common antigens (molecular weights, 28, 34, 36 and 40 kDa) that reacted with sera from all strains and one consisting of specific antigens (molecular weights 31, 65 and 69 kDa) that reacted only with sera from distinct strains. Blot analysis of sera from H-2 congenic strains demonstrated that the reactivity to the second group of antigens was regulated by the H-2 complex. In B10 intra-H-2 recombinant strains, only the I-Ab allotype strains produced immunoglobulin G antibody that reacted to the 65 kDa antigen. This evidence indicates that the primary immune response to the A. actinomycetemcomitans antigen with a molecular weight of 65 kDa is controlled by genes in the I-A subregion of the H-2 complex. This 65 kDa antigen was also highly reactive with some human sera from early-onset periodontitis patients. Further analysis of this antigen is required.