Immunohistological analysis of T cell functional subsets in chronic inflammatory periodontal disease
IL‐2, interferon‐gamma (IFN‐γ), IL‐4 and IL‐6 producing T cells in periodontitis and gingivitis‐affected human tissues were investigated by immunohistochemistry to clarify the relationship between T cell functional subsets and disease entity. Using alkaline‐phosphatase anti‐alkaline‐phosphatase technique, the relative proportions of each cytokine‐producing T cell were calculated in the crevicular 1/3, middle 1/3 and oral 1/3 areas selected in the connective tissue of sections. CD19:CD3 and CD4:CD8 ratios were determined on the serial sections. Compared with gingivitis tissues, the proportion of cytokine‐producing cells in periodontitis‐affected samples was higher overall in the crevicular 1/3 (P < 0·02). The middle 1/3 exhibited a higher percentage of cytokine‐producing cells, except for IL‐6‐producing cells. Frequencies of cytokine‐producing cells in the oral 1/3 did not differ. IL‐4 was the prominent cytokine in periodontitis‐affected tissues, with the highest proportion detected in the crevicular 1/3. The CD19:CD3 ratio was higher in periodontitis tissues irrespective of the location, indicating a B cell dominance in periodontitis lesions. Furthermore, a significant positive correlation between the proportion of IL‐4‐producing cells and the CD19:CD3 ratio was noted. The CD4:CD8 ratio consistently exceeded 2·0 in both periodontitis and gingivitis. These results suggest that immunoregulation of both periodontitis and gingivitis are T cell‐dependent, but in periodontitis type 2 helper T cells predominate and thereby control B cell activation.