Serum Antibody Activity Against Actinobacillus Actinomycetemcomitans in Chinese Patients with Periodontitis

Actinobacillus Actinomycetemcomitans (Aa) has been implicated as a periodontopathogen in juvenile periodontitis(JP). Certain Aa posses leukotoxin which kills PMNs as reflected by the extracellular discharge of 51. Cr from labeled PMNs. The leukotoxin activity can be neutralized by specific rabbit anti-Aa serum or by a majority of JP patients sera as reported by many investigators in the U. S. A. The purpose of the present study was to screen a number of sera to determine if leukotoxin neutralization activities and antibodies against other Aa antigens are associated with periodontitis in Chinese patients. Sera were analysed for the presence of antileukotoxin antibodies as assayed by inhibition of Aa-mediated killing of human PMNs and for antibodies against sonic extracts of various Aa serotypes by immunodiffusion. When compared with normal individuals, it was obvious that JP and ADP (advanced destructive periodontitis) and a majority of AP (adult periodontitis) has high antileukotoxin activity in their sera. Immunodiffusion data indicated that greater than 60% of JP, ADP patients reacted to antigens found in the Aa(mainly to serotype c or strain 652). The leukotoxin-neutralizing activity seems to correlate with clinical severity of periodontitis with thresholds of gingival index≦1.5 and of alveolar bone loss ≦40%but not to those of more advanced cases. These results show that periodontal destruction in Chinese periodontitis patients especially JP and ADP is associated with infection by and an immune response to Aa.