Tumor necrosis factor in benign and malign tissue of the kidney

Summary The use of tumor necrosis factor (TNF) in immunotherapy of tumor diseases has attracted increasing interest. Since the direct antitumor effect of the TNF is mediated by receptor-bound TNF, we immunohistologically stained both benign and malignant tissue from 35 tumor-bearing human kidneys for TNF. Using a polyclonal anti-TNF-antiserum, paraffin sections were tested in the presence and absence of in vitro preincubation with TNF. Futhermore, all specimens were stained immunohistologically for Tamm-Horsfall protein (THP) because this renospecific glycoprotein can bind TNF in a lectin-like manner. In the absence of TNF preincubation, malignant tissue was TNF-positive in 34 specimens, as was benign tissue from the same tumor-bearing kidneys in 35 cases. In several specimens the staining was so intense that preincubation with TNF did not enhance the reaction. Whereas TNF staining in tumor tissue was relatively homogenous, that in benign tissue was intensive in distal tubuli, moderate in proximal tubuli, and negative in glomeruli. THP staining was negative in malignant kidney tissue but positive in the distal tubuli of benign tissue, i. e., in the regions in which TNF staining was most intense. These results indicate that TNF binds not only to membrane, most likely in a receptor-mediated manner, but also to THP both in vivo and in vitro. In vivo binding of TNF to THP was confirmed in animal experiments in which pigs were given injections of TNF. Immunohistological staining of the animals' kidneys revealed positive reactions for both TNF and THP at the distal tubuli, indicating TNF binding to THP after in vivo TNF administration. The presence of TNF in human kidney tumors implies that renal-cell carcinoma cells in situ are resistant to the direct cytotoxic effect of TNF. This resistance should be taken into account when TNF is considered for use as a possible immunotherapeutic agent in renal-cell carcinoma.