Nasal natural killer (NK)/T-cell lymphoma is an Epstein-Barr virus (EBV)-related malignancy with poor prognosis and has distinct histological features characterized by angiocentric and polymorphous lymphoreticular infiltrates including inflammatory cells such as granulocytes, monocytes, macrophages and lymphocytes. Recently, the role of chemokines in tumor proliferation and invasion has been shown. Furthermore, chemokines are likely to play important roles in the pathophysiology of diseases associated with EBV. We examined the chemokines expressed by nasal NK/T-cell lymphoma. Nasal NK/T-cell lymphoma cell lines produced IP-10, TARC, MDC, IL-8, and MCP-1. IP-10 enhanced lymphoma cell invasion through an autocrine mechanism. Next, we examined whether inflammatory cells influence the biological activities of nasal NK/T-cell lymphoma cell lines. We cocultured nasal NK/T-cell lymphoma cell lines with monocytes. Cocultured monocytes enhanced the proliferation of cell lines. Immunohistological studies showed confirmation that a number of infiltrating CD14-positive monocytes were in contact with CD56-positive lymphoma cells in the nasal NK/T-cell lymphoma tissues. These results suggest that chemokines such as IP-10, MDC, and MCP-1 produced by nasal NK/T-cell lymphoma cells attract monocytes through a paracrine mechanism and the attracted monocytes enhance proliferation of lymphoma cells.
