Detection of carcinogenic exposures by urinalysis: induction of cell-mediated immunity.

Studies were undertaken to determine whether urine collected from rats during the 24 h following exposure to the colon carcinogen 1,2-dimethylhydrazine (DMH) contained substances which would induce specific antitumor immunity. The evaluation for such components was carried out by administering the test and control urine to young male adult Fisher F344 inbred rats and then establishing the animals' antitumor cell-mediated immunity (CMI) at a 14-day post-exposure interval. The CMI was measured by determining the injury and destruction inflicted upon cultured X-ray-induced rat small bowel adenocarcinoma target cells by peripheral blood lymphoid cells obtained from the animals exposed to the urine. A significantly increased CMI was found to be induced by the urine collected from the chemically exposed rats, thus suggesting the presence of mutagenic/carcinogenic components. In addition, exposure through the levels of CMI that were induced, with an approximate threshold detection limit of 100 microgram (1.7 mumol)/kg body weight (100 ppb) to the chemical. These preliminary findings suggest that such immune measurements might serve as a basis for the development of a rapid and inexpensive bioassay for monitoring population exposures to carcinogenic substances.