Materials and Methods

Kidney samples. Renal tissue was obtained from 51 patients who underwent nephrectomy. No more tissue was removed surgically than was clinically indicated. Resected tissue that W58 free of tumor was immediately placed on dry ice and was stored at-85#{176} C. Renal TPMT activity was stable during storage under these conditions. The pathological diagnoses for these 51 kidney samples were: renal cell carcinoma (42), papillary transitional cell carcinoma(5), metastatic transitional cell carcinoma(1), renal cortical adenoma (1), hydronephrosis involving only the upper calyces (1) and fibrous walled renal cyst (1). All renal tissue was obtained under guidelines established by the Mayo Clinic Human Studies Committee.

Blood samples. Blood samples anticoagulated with heparin were obtained from 20 of the patients from whom renal tissue had been obtained. Blood samples were also obtained from randomly selected adult blood donors at the Mayo Clinic in Rochester, MN. All subjects were white, and, with the exception of surgical patients, none were taking medication. All blood samples were also obtained under guide-lines established by the Mayo Clinic Human Studies Committee. RBC lysates were prepared as described elsewhere(Weinshilboum et al., 1978). After TPMT enzymatic activity in the samples had been measured, the RBC lysates were stored at-85#{176} Cfor less than 3 weeks before immunotitration. TPMT enzymatic activity is stable under these conditions(Weinshilboum et al., 1978).‘FPMT assay. TPMT enzymatic activity was measured by the method of Weinshilboum et al.(1978). The assay is based on the