Presence of IFN-gamma and IL-4 in human periapical granulation tissues andregeneration tissues

To study mediators associated with the progression of disease and the proce ss of bone regeneration in human apical periodontitis, we examined samples of periapical granulation tissues and regeneration tissues obtained from fi ve patients by use of immunohistochemical methods. Periapical granulation t issues were found to contain a large number of CD4-positive T cells and CD6 8-positive monocytes/macrophages (CD4: 35.2%, CD68: 32.7%), The CD4-positiv e T cells and CD68-positive monocytes/macrophages were predominantly presen t in regeneration tissues (CD4: 62.1%, CD68: 16.0%), In these the percentag es of CD4-positive T cells were higher as compared with periapical granulat ion tissues (from 35.2% to 62.1%), In periapical granulation tissues, CD4-p ositive T cells stained positively for interferon-gamma (IFN-gamma) and neg atively for interleukin-4 (IL-4), In regeneration tissues, IL-4-producing c ells could be detected. However, IFN-gamma -producing cells could not be de tected. These results suggest that IFN-gamma and IL-4 may modulate the path ogenesis of infectious disease and the process of bone regeneration in loca l inflammation sites such as human apical periodontitis. (C) 2001 Academic Press.