SERUM ANTIBODY OPSONIC ACTIVITY AGAINST ACTINOBACILLUS-ACTINOMYCETEMCOMITANS IN HUMAN PERIODONTAL-DISEASES

Actinobacillus actinomycetemcomitans is frequently associated with sev ere periodontitis. Many periodontitis patients have elevated levels of serum IgG antibodies to A. actinomycetemcomitans, but the role of the se antibodies is unknown. This study evaluated the functional capacity of anti-A. actinomycetemcomitans IgG antibody to enhance phagocytosis of A. actinomycetemcomitans by polymorphonuclear leukocytes. Chemolum inescence assays were done using sera from 64 subjects, 61 of whom had severe periodontitis; results were compared with the subject's anti-A . actinomycetemcomitans IgG titer and avidity. There was a strong corr elation between chemoluminescence and antibody log titer (P < .00001) and a weak correlation between chemoluminescence and antibody avidity (P < .05). The results support the hypothesis that anti-A. actinomycet emcomitans IgG antibodies are important in promoting phagocytosis and killing of A. actinomycetemcomitans. Subjects who develop high levels of highly avid antibodies against A. actinomycetemcomitans may have gr eater resistance to continued or repeated infection by this pathogen.