Enhanced expression of ELAM-1 on endothelium of renal cell carcinoma compared to the corresponding normal renal tissue

Renal cell carcinoma (RCC) has been shown to respond to an immunological th erapy with tumor infiltrating lymphocytes (TIL), which accumulate in RCC at a higher density than in normal renal tissue, suggesting that there is sel ective tumor invasion, Since invasion of TIL into the malignant tissue is m ediated by adhesion molecules, we examined the different expression of the adhesion molecule endothelial-leukocyte-adhesion-molecule- 1 (ELAM-1) on en dothelial cells of RCC versus normal renal tissue. For a specific quantific ation, the level of ELAM-1 mRNA was investigated by both semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis and referred to the content of endothelial cells in the tissue, de termined by endothelium specific staining. Quantification of mRNA was evalu ated by computer-aided integration. We observed a significantly lower amoun t of endothelial cells in RCC compared to normal renal tissue. The specific transcription rate of ELAM-1 in RCC, determined by RT-PCR was about 5.2 ti mes that of normal tissue, while Northern blot analysis indicated an approx imately 11.8 times increase. Our investigations show a significantly increa sed expression of ELAM-1 in tumor tissue compared to normal renal tissue, p resumably caused by a higher amount of cytokines in the tumor tissue. This enhanced expression may be responsible for the high concentration of TIL in renal tumors. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.