An immunohistochemical study of tissue transglutaminase in gliomas with reference to their cell dying processes.

Tissue transglutaminase is a Ca(2+)-dependent enzyme that catalyzes the formation of protein cross-links by an acyl transfer reaction. Recent reports have suggested that tissue transglutaminase is induced by tumor progression and apoptosis. In this study we immunohistochemically investigated a series of gliomas by using an antiserum against a dodecapeptide from the COOH-terminal of tissue transglutaminase. Among the gliomas the presence of positive immunoreactivity tended to increase in malignant counterparts. It is also noteworthy to mention that glioblastoma cells surrounding the zonal necrosis in a palisade fashion were strongly immunolabeled. The degenerating products in tumor cells, such as round granulated bodies, were primarily immunopositive, whereas Rosenthal fibers were negative. Dying cells through apoptosis in the metastatic brain tumors could be easily recognized by the presence of tissue transglutaminase. In conclusion, tissue transglutaminase may therefore be valuable in the prognostic characterization of gliomas with respect to the detection of dying cells. However, the appearance of tissue transglutaminase-positive neoplastic cells was not limited to apoptotic bodies but could also be detected in necrobiotic cell nests.