Immunohistological characteristics of periodontal lesions associated with Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans infections.

In this study, various phenotypes of infiltrating cells in the periodontium adjacent to pockets harboring Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were evaluated. Furthermore, the pattern of class II antigen expression in the periodontal tissues was determined. Eight lesions were associated with the presence of P. gingivalis and 12 with A. actinomycetemcomitans. Predominant cells in the inflammatory infiltrate were T- and B-cells. In most biopsies T-cells dominated over B-cells. The proportion of P. gingivalis, but not of A. actinomycetemcomitans, was positively correlated to the total number of infiltrating cells in the tissue. A. actinomycetemcomitans sites demonstrated somewhat lower proportions of CD3+, CD4+ and CD19+ cells than P. gingivalis sites. However, the tendency of decreasing CD4+/CD8+ ratio with increasing number of A. actinomycetemcomitans indicates a local imbalance in immunoregulation. The frequency of class II antigen expression of both mononuclear and epithelial cells, a sign of immunological activation, was generally high.