[Analysis of antigens of Actinobacillus actinomycetemcomitans with monoclonal antibodies].

The purpose of this study was to analyze antigens of Actinobacillus actinomycetemcomitans. Fifteen hybridomas producing monoclonal antibodies (MAbs) against A. actinomycetemcomitans strain Y4 were obtained. These hybridomas were divided into three groups (Group 1, Group 2 and Group 3) on their MAbs' specificity. The MAbs (MAb S1-S8) produced by Group 1 hybridomas reacted with serotype b-specific antigen of A. actinomycetemcomitans. The MAbs (MAb L1-L3) produced by Group 2 hybridomas reacted with lipopolysaccharides (LPSs) of all serotypes of A. actinomycetemcomitans. The high-molecular-weight peak (peak A) and the low-molecular-weight peak (peak B) were separated by gel-filtration of the phenol-water extract (PWE) of strain Y4. MAb S5 reacted with peak A, and MAb L2 reacted with peak B. Peak B bound to a polymyxin affinity column, but peak A did not. These findings indicate that peak A was serotype-specific antigen and peak B was LPS. MAbs P1, P2, P3 and P4 produced by Group 3 hybridomas reacted with 81 kDa, 64 kDa, 64 kDa and 40 kDa protein antigens, respectively. Preincubation of strain Y4 whole cells with MAb P3 inhibited significantly the adherence of the cells to human buccal epithelium cells (HBECs). These findings suggest that the 64 kDa protein antigen might participate in the adherence of A. actinomycetemcomitans to HBECs.