In situ hybridisation for cytokine gene transcripts in the solid tumour microenvironment.

To determine if mononuclear cells (MNC) infiltrating various types of human solid tumours express genes for cytokines, in situ hybridisation with 35S-labelled cDNA antisense probes for interleukin 2 (IL2), interferon gamma (IFN-gamma), tumour necrosis factor alpha (TNF-alpha), interleukin 1-beta (IL1-beta), transforming growth factor beta (TGF-beta) and interleukin 2-receptors (IL2R) was performed. Fresh-frozen tissue samples of ovarian carcinomas (n = 13), breast carcinomas (n = 12), and squamous cell carcinomas of the head and neck (SCCHN, n = 7) were evaluated for the presence and localization in the tumour of MNC positive for cytokine genes. In ovarian tumours and those breast carcinomas producing little or no mucin, only rare positive MNC were observed. In contrast, breast carcinomas producing mucin and all SCCHN contained numerous MNC expressing gene transcripts for IL2, IFN-gamma, TNF-alpha, IL2R as well as TGF-beta. In tumour-involved lymph nodes of patients with SCCHN, MNC expressing genes for cytokines were found around tumour metastases but not in non-involved areas. These data suggest that tumours expressing immunogenic antigens (e.g. mucin) contain many activated MNC, while other tumours either fail to activate or suppress functions of infiltrating MNC. In SCCHN or tumour-draining lymph nodes, local down-regulation of antitumour responses might be mediated by TGF-beta produced by activated tumour-infiltrating MNC.