[Bacteriological and immunological studies on the mechanism of development of periapical lesion. Immunobiological activities and localization in periapical lesion of the cellular components from Bacteroides buccae].

It has been strongly suggested that the periapical lesion develop as a result of immunopathological response to continuous antigenic stimulation. Bacteria from root canal systems might be most important pathogenesis capable of inducing immunological reactions in periapical tissue. The purpose of this study, therefore, was clarify the immunological potentials of Bacteroides buccae (B. buccae) which was frequently isolated from root canals with chronic periapical lesion. Biological activities of B. buccae cellular components, such as lipopolysaccharides (LPS) and cellular protein were investigated on the enhancement of monocytes migration induction of interleukin 1 (IL-1) production, mitogenicity and polyclonal B cell activation. The localization of immunocompetent cells and B. buccae in human chronic periapical lesions were examined by biotin-avidin-horseradish peroxidase method, and peroxidase antiperoxidase methods using monoclonal antibodies. Following results were obtained. 1. On the lymulus lysafe clotting activity and Shwarzman activity of B. buccae LPS were about half of Salmonella typhimurium (S. typhimurium). 2. Both LPS and 38K protein preparations from B. buccae enhanced the activity of human peripheral monocytes migration and induced IL-1 production. 3. It was found that mitogenicity of LPS from B. buccae on splenocytes of BALB/c and BALB/c nu/nu mice was weaker than that of 38K protein, however mitogenicity on thymocytes were not shown in both preparations. 4. The polyclonal B cell activation on splenocytes of BALB/c nu/nu mice by B. buccae were remarkably induced by 38K protein, but LPS showed less activity elicit than 38K protein. 5. It might be suggested that the both LPS and 38K protein of B. buccae may depend on the activities of macrophage and lymphocytes. 6. Antigenic substance of B. buccae were found most commonly engulfed materials within macrophage and intercellular space in connective tissue. 7. Dense accumulation of T and B lymphocytes were observed gathering around the phagocytic macrophage (foam cell), the number of B lymphocytes around the macrophage was greater than that of T lymphocytes. 8. These findings indicated that both LPS and 38K protein from B. buccae have a wide regulation function of immunobiologic responses. Therefore, it was suggested that both LPS and 38K protein from B. buccae may play significant roles in the pathogenesis of periapical lesion.