Human sarcomatous Wilms' tumor. Characterization with 5H10, a newly established monoclonal antibody

Immunophenotypic features of human sarcomatous Wilms' tumor (SWT) were studied using a newly established mouse monoclonal antibody (5H10, IgG1). 5H10 was produced against CR-SW2, one of several transplanted SWT lines in nude mice, and defines a 200-kDa cell surface protein. The antibody was found to react equally with all subtypes of SWT; clear cell sarcoma of the kidney, malignant rhabdoid tumor of the kidney, and unclassified sarcoma. Furthermore, it reacted equivalently with surgically resected tumors, transplanted tumors in nude mice, and cell lines in vitro. On the other hand, 5H10 was entirely negative for any of the components of nephroblastic Wilms' tumor (NBW). Considering these results, 5H10 appears to recognize the antigen expressed preferentially on SWT, and therefore the subtypes of SWT may be closely related to one another immunophenotypically. In normal human tissues, however, 5H10 only reacted with fetal kidneys, its reactivity being restricted to the lower limbs of S-bodies in both the metanephros and mesonephros. No reactivity was identified in any other tissues including adult kidney. These results indicate that 5H10 detects an oncofetal antigen expressed preferentially in both SWTs and fetal kidney and that the histogenesis of SWT should be considered in connection with nephrogenesis.