MARKING HYPOXIC CELLS FOR COMPLEMENT AND CYTOTOXIC T-LYMPHOCYTE-MEDIATED LYSIS - USING PIMONIDAZOLE

Artificial antigens are created when 2-nitroimidazoles bind to hypoxic cells. These antigens have been used in the immunodetection of tumour hypoxia but they might also serve to stimulate immune lysis of hypoxi c tumour cells by complement- and cell-mediated processes. In order to test this hypothesis, lymphocytes isolated from the spleens of C3H/He N mice that had been immunised with pimonidazole-labelled 3152-PRO cel ls were subcultured and tested for their ability to lyse chromium-51 l oaded, pimonidazole-labelled 3152-PRO cells in an in vitro assay. In a parallel study, commercially available, rabbit complement was tested for its ability to lyse pimonidazole-labelled V79-4 cells in the prese nce of monoclonal antibodies which recognise protein adducts of reduct ively activated pimonidazole. Complement-mediated cell lysis was measu red by means of an MTT assay. Complement-mediated and cell-mediated ly sis was observed at pimonidazole concentrations which, in themselves, do not produce cell killing.