Expression of MUC1, Thomsen-Friedenreich-related antigens, and cytokeratin 19 in human renal cell carcinomas and tubular clear cell lesions

The expression of MUC1, MUC2, mucin-associated Thomsen-Friedenreich-related antigens (TF, sialosyl-TF, Tn, and sialosyl-Tn), and cytokeratin 19 (CK19) was systematically investigated in situ in 58 resected human kidney rumours, surrounding tissue of normal appearance, and two normal kidneys obtained at autopsy, using monoclonal antibodies. In kidney tissues of normal appearance, TF, s-TF, MUC1 and CK19 were positive in distal tubules and collecting ducts but negative in proximal tubules. In contrast, MUC2, Tn, and s-Tn were negative throughout the normal renal tubular system. Almost all renal cell carcinomas (RCCs) showed strong immunoreactivity for MUC1, but all were negative for MUC2. Some RCCs expressed TF, Tn, s-Tn, and CK19. In addition, the immunomorphological characteristics of the majority of clear-cell RCCs and clear/granular RCCs with anti-MUC1 and anti-CK 19 closely resembled those of the collecting duct and the distal tubule rather than the proximal tubule. In the renal tissue of otherwise normal appearance adjacent to clear-cell RCCs and clear/granular RCCs, clear cells with excessive storage of glycogen were often found in the collecting duct system, but only rarely in the proximal tubules. These results suggest that the majority of clear-cell RCCs and clear/granular RCCs may originate from the collecting duct system.