Interleukin-18 (IL-18) has been found to have multiple effects upon various
cells involved in inflammatory response. Recently we reported that B16 mur
ine melanoma cells are able to produce IL-18, which is involved in the regu
lation of intracellular reactive oxygen intermediates (ROI) and Fas-ligand
expression, indicating that IL-18 plays key role in the tumor activity of m
elanoma. In this study, we investigated the pattern of IL-18 expression in
the human system. IL-18 production was tested by enzyme linked immunosorben
t assay (ELISA) assay in various tumor cell lines, including Raji (Burkett'
s lymphoma), IM-9 (B lymphoblast), Jurkat (acute T cell leukemia), SK-MES-1
(squamous cell carcinoma (SCC) cell line), SK-MEL-2, G-361, DM-4, and DX-3
(melanoma cell lines). ELISA tests showed that IL-18 was highly expressed
in malignant skin tumors such as SK-MES-1, SK-MEL-2, G-361, DM-4, and DX-3
cell lines, thus suggesting that IL-18 production may be associated with th
e malignancy of skin tumors. Here, we report that enhanced IL-18 expression
is positively correlated with malignant skin tumors such as SCC and melano
ma, suggesting the importance role of IL-18 in malignancy of skin tumors. T
aken together, expression of IL-18 by tumor cells in human skin tissue may
provide an important clue to understand the pathogenesis of malignant skin
tumors. (C) 2001 Elsevier Science B.V. All rights reserved.