Background and objectives: Solid tumors evade the host immunologic responses they initiate by unknown mechanisms. The authors investigated patterns of cytokine content in human colon carcinomas, colon cancer cell lines in vitro, and nude mouse xenografts from those lines in order to clarify those mechanisms.
Methods: Epithelial tumor cell lines were developed from specimens of human colon adenocarcinoma. Aliquots of these cells were then xenografted into female heterozygous BALB/c nu/+ immunologically deficient mice and serially passaged. Original tumors, cell lines, and resultant xenografts were then analyzed for histology/cytology and for levels of TGF-beta and TNF-alpha by enzyme linked immunoassay.
Results: Cytokine levels were elevated beyond baseline mucosal levels in original tumors and xenograft mouse tumors but not detectable in extracts from epithelial cultures.
Conclusions: While the precise source of cytokine production remains unclear, these data suggest tumor/host interactions not found in pure epithelial cancer cells in culture.