Increased thymocyte-activating factor in human gingival fluid during gingival inflammation.

In this study, human gingival fluid from normal subjects was shown to contain a low-molecular-weight factor (molecular weight, 10,000 to 25,000) which augmented murine thymocyte proliferation, enhanced the production of interleukin 2 by T lymphocytes, and augmented the proliferation of fibroblasts. These biochemical and biological properties are characteristic of both macrophage-derived interleukin 1 and epidermal cell-derived thymocyte-activating factor. In addition, we have established that epidermal thymocyte-activating factor or interleukin 1 or both are present to a greater extent in gingival fluid obtained from sites manifesting gingival inflammation. In fact, thymocyte-activating activities were found to be greater in gingival fluid from inflamed than from noninflamed gingival sites from the same subjects. These findings suggest that human gingival fluid contains epidermal thymocyte-activating factor or interleukin 1 or both, which may amplify the inflammatory response in periodontal tissues.