Comparative antibody titers to Actinobacillus actinomycetemcomitans in juvenile periodontitis, chronic periodontitis and periodontally healthy subjects.

Circulating antibody levels to four strains of Actinobacillus actinomycetemcomitans (Aa) were determined by means of an indirect immunofluorescent technique in three groups of 21 subjects each, including one with juvenile periodontitis (JP), one with chronic periodontitis (CP) and one free of periodontal disease (N). Mean levels of antibody to Aa were significantly elevated in the JP group as compared to the CP and N groups with respect to strains Y4, 29522 and 29524, but not strain 29523. Since strains Y4, 29522 and 29524 contain a leukotoxin that is missing from strain 29523, the results suggest that the leukotoxin could account for the difference in the immune response among the three groups of subjects. Varying the end-point considered to represent positive fluorescence did not significantly affect the results, although discrimination among the three groups appeared to be somewhat better at lower intensities of fluorescence. Because of wide variations in antibody titers recorded in individual subjects, elevated levels of antibody to certain strains of Aa may not be useful as a primary diagnostic test for JP, but may be of value in confirming an otherwise uncertain clinical diagnosis.