O. Takeichi et al., Inducible nitric oxide synthase activity by interferon-gamma-producing cells in human radicular cysts, INT ENDOD J, 32(2), 1999, pp. 124-130
Aim In this study, the interaction of interferon-gamma-(IFN-gamma) and indu
cible nitric oxide synthase (INOS)-producing cells in human radicular cysts
were investigated.
Methodology Inflamed periapical tissues were obtained from patients at the
time of endodontic surgical treatments and were cut into two pieces. After
fixing with acetone or 4% paraformaldehyde in phosphate-buffered saline. 5-
m-thick paraffin and cryostat sections were prepared. The paraffin sections
of the inflamed tissues were evaluated histologically with haematoxylineos
in stains, The specimens diagnosed as radicular cysts were then examined by
immunostaining. Immunohistochemistry for iNOS and fluoresence microscopy f
or IFN-gamma using the cryostat sections were performed with a mixture of a
ffinity purified human iNOS antiserum and human IFN-gamma monoclonal antibo
dies.
Results The results revealed that iNOS-gamma producing cells localized adja
cent to IFN-gamma-producing cells, In addition, some of iNOS-producing cell
s exhibited immunoreactive IFN-gamma. On the other hand, epithelial cells s
howed significant levels of iNOS production. but not IFN-gamma.
Conclusions The data would suggest the possibility that INOS production cou
ld be precisely controlled by autocrine or paracrine effects of IFN-gamma p
roducing cells in radicular cysts and might play a pivotal role in periapic
al lesions. These findings are consistent with a hypothesis suggesting that
NO inhibitors could be used through the root canals as a pharmacological t
reatment for periapical lesions.