DETECTION OF INTERLEUKIN-8 MESSENGER-RNA AND PROTEIN IN HUMAN COLORECTAL-CARCINOMA CELLS

Interleukin-8 (IL-8) is a member of the chemokine family of pro-inflam matory chemotactic cytokines and is secreted by some human colorectal carcinoma cell lines. We have used in situ hybridisation and immunohis tochemistry to determine whether IL-8 mRNA and protein, respectively, are produced by human colorectal carcinoma cells in vivo. IL-8 mRNA wa s detected within the cytoplasm of tumour cells in all nine samples te sted, including that of a tumour which had metastasised to a lymph nod e. Non-involved colonic mucosa within the same tissue blocks showed mu ch weaker labelling. IL-8 protein was detected in 74% (23/31) of tumou r samples and was mainly localised to the tumour cell cytoplasm. In 30 % of cases, staining was heterogeneous, with between 1 and 30% of cell s being positive. In some tumour cells, IL-8 showed a perinuclear dist ribution resembling that found by in situ hybridisation. Some infiltra ting leucocytes, endothelial cells and fibroblast-like cells within th e tumour sections were also positive for IL-8 mRNA and protein. The po ssibilities that colorectal tumours produce IL-8 to aid invasion and/o r metastasis or as a tumour growth factor are discussed. Copyright (C) 1996 Elsevier Science Ltd