Marking hypoxic cells for complement and cytotoxic T lymphocyte-mediated lysis: using pimonidazole

Area of Science:

• Immunology
• Oncology
• Biochemistry

Background:

• Artificial antigens are formed when 2-nitroimidazoles bind to hypoxic cells.
• These antigens are utilized for detecting tumor hypoxia.
• Potential for these antigens to stimulate immune lysis of hypoxic tumor cells exists.

Purpose of the Study:

• To investigate the hypothesis that artificial antigens can stimulate immune lysis of hypoxic tumor cells.
• To assess complement-mediated and cell-mediated lysis of tumor cells presenting artificial antigens.

Main Methods:

• Lymphocytes from immunized mice were tested for their ability to lyse chromium-51 labeled, pimonidazole-labeled tumor cells in vitro.
• Commercially available rabbit complement and monoclonal antibodies were used to test for complement-mediated lysis of pimonidazole-labeled cells.
• Cell lysis was measured using chromium-51 release and MTT assays.

Main Results:

• Both complement-mediated and cell-mediated lysis of pimonidazole-labeled tumor cells were observed.
• Lysis occurred at pimonidazole concentrations that did not cause direct cell killing.
• Monoclonal antibodies recognizing reductively activated pimonidazole adducts enhanced complement-mediated lysis.

Conclusions:

• Artificial antigens derived from 2-nitroimidazoles can indeed elicit immune responses leading to the lysis of hypoxic tumor cells.
• This immune-mediated lysis can be achieved through both complement-dependent and cell-dependent mechanisms.
• The findings suggest potential therapeutic applications of artificial antigens in cancer immunotherapy.