TRANSFORMING GROWTH-FACTOR-BETA-1 IS SIGNIFICANTLY ELEVATED IN PLASMAOF PATIENTS SUFFERING FROM RENAL-CELL CARCINOMA

The levels of active and latent transforming growth factor beta 1 (aTG F-beta 1, ITGF-beta 1, respectively) in plasma samples were measured b y enzyme-linked immunoabsorbent assay (ELISA). Samples were collected from patients suffering from renal cell carcinoma (RCC) before they un derwent tumour resection, In all cases tested, the levels of latent TG F-beta 1 were much higher (n = 23, 41.0 +/- 13.9, range 19.3-78.1 ng/m l) than in healthy controls (n = 21, 3.8 +/- 2.9, range 0.6-9.9, P muc h less than 0.0001), while active TGF-beta 1 did not differ that impre ssively (n = 38, 1.2 +/- 1.3, range 0.0-4.5 for RCC, n = 21, 0.1 +/- 0 .2, range 0.0-1.1 in controls, P < 0.001), As for TGF-beta 1 productio n by proximal tubulus cells has been shown, it was speculated that the se high TGF-beta 1 levels might be due to secretion by the tumour, whi ch usually originates from proximal tubuli. Indeed, production of TGF- beta 1 was found in culture supernatants, and it was possible to show TGF-beta 1 mRNA expression in tumour samples, This TGF-beta 1 was pred ominantly secreted in the latent form, This is in contrast to data fro m other authors, who found TGF-beta 1 to be secreted mainly in the act ive form, but need not mean that it is inactive locally as the low pH encountered within tumours is in the range necessary for its activatio n, It is concluded that elevated latent TGF-beta 1 is common in RCC, i s at least partially produced by the tumour and might be a cause for l ocal immunosuppressive effects within the tumour. (C) 1996 Academic Pr ess Limited