Nasal T/NK cell lymphomas commonly express perforin and Fas ligand: important mediators of tissue damage

Aims: Two molecular mechanisms of T/natural killer (NK) cell-mediated cytotoxicity, one perforin based and the other Fas based, have been demonstrated, and both systems induce cytotoxicity in the target cells, The Fas-based mechanism involves the transducing molecule Fas and its ligand (FasL). In addition, perforin and/or Fast are also expressed in the cytotoxic T/NK cells, This study was thus designed to investigate the Fas and perforin pathways of the cylotoxic T/NK lymphoma cells in the nasal cavity. Methods and results: Eight patients with nasal lymphoma were analysed using immunohistochemical staining methods. Two cases were CD3+ CD56+ (T/NK cell) type, and six were CD3-CD56+ (NK cell) type, All cases showed Epstein-Barr virus genomes by in-situ hybridization, In addition, all cases showed the expression of TIA-1 (GMP-17), which is a marker of cytotoxic T and NK cells, Fast was expressed in the majority of the lymphoma cells and some histiocytes, while Fas was found in lymphoma cells and many non-neoplastic cells, In addition, the expression of perforin was detected in almost all lymphoma cells, In the double stainings. lymphoma cells expressed both Fast and perforin, Based on these findings, both the perforin- and Fas-based pathway of the cytotoxic T/NK lymphoma cells are thus considered to play an important role in the clinical features, Conclusions: Tissue damage is a common morphological feature in nasal T/NK cell lymphoma. The above findings therefore the theory that issue damage is due to the cytotoxicity of T/NK lymphoma cells as well as to angiocentricity.