Measurement of urinary trypsin inhibitor in urine, plasma and cancer tissues of patients with stomach cancer.

Antiserum was obtained from rabbits immunized with a highly purified preparation of urinary trypsin inhibitor (UTI) conjugated with rabbit serum albumin. Anti-UTI antibody did not cross-react with antibody against inter-alpha-trypsin inhibitor (I alpha I) as determined by immunodiffusion against human plasma. A highly sensitive enzyme immunoassay was developed for the determination of UTI-related antigens (UTIR) in plasma, urine and cancer tissues. The level of UTIR correlated with UTI activity in urine. UTIR levels in urine and plasma did not change with age, but UTIR levels were higher in the stomach cancer tissue than in the surrounding stomach mucosa. UTIR levels did not correlate with I alpha I levels in the plasma of patients with stomach cancer, thus the increase was not considered due to the contamination of circulating I alpha I in the cancer tissues.