Comparison between the expression of adhesion molecules in the endotheliumof renal cell carcinomas and healthy kidney tissue

Purpose: Spontaneous remission of renal cell carcinoma is a relatively freq uently observed event compared with other tumor entities usually associated with a high accumulation of tumor infiltrating lymphocytes (TIL) in the tu mor tissue. The lymphocyte infiltrative in renal cell carcinoma shows a dif ferent composition of subclasses compared to peripheral blood and a higher concentration than in normal renal tissue, suggesting selective tumor invas ion. The first step in an immunological reaction to renal cell carcinoma is the extravasation of TIL into the malignant tissue, which is mediated by a dhesion molecules. We examined the different expression of the adhesion mol ecule endothelial-leukocyte-adhesion-molecule-1 (ELAM-1) on endothelial cel ls of RCC and normal renal tissue. Materials and Methods: For a specific quantification of ELAM1 in renal cell carcinoma and the corresponding normal renal tissue, the level of ELAM-1 m RNA in frozen sections of 10 patients was investigated by both semiquantita tive RT-PCR and Northern blot and referred to the content of endothelial ce lls in the tissue, determined by endothelium-specific staining. Quantificat ion of mRNA was performed by a computer-based densitometric integration. Results: We observed a tenfold lower content of endothelial cells in RCC co mpared to normal renal tissue. The specific transcription rate of ELAM-1 in renal cell carcinoma as determined by RT-PCR was about 5.2 times higher th an normal renal tissue, and, as determined by Northern blot it was about 11 .8 times higher. Conclusions: Our investigations show a significantly increased expression o f ELAM-1 in tumor tissue as compared to normal renal tissue in the same pat ient, presumably caused by a higher amount of cytokines in tumor tissue. Th is enhanced expression may be responsible for the high concentration of TIL in renal tumors.