Detection of inflammatory cytokine messenger RNA (mRNA)-expressing cells in human inflamed gingiva by combined in situ hybridization and immunohistochemistry.

Cells expressing messenger RNA (mRNA) for inflammatory cytokines [interleukin-1 (IL-1), tumour necrosis factor-alpha (TNF-alpha), IL-6, IL-8] were demonstrated by in situ hybridization in human inflamed gingiva. When this technique was used in conjunction with immunohistochemistry, IL-1 alpha and/or beta and IL-8 messages were observed predominantly on macrophages infiltrating the gingiva. TNF-alpha messages were abundant on macrophages and T cells. In contrast, the IL-6 mRNA were more widely distributed on many types of cells such as macrophages, T cells, fibroblasts, endothelial cells and B cells. This study clearly identified the cells which express mRNA for inflammatory cytokines in inflamed gingiva and suggested an involvement of cytokine network in the generation of human periodontitis.