Abstract
The Tasmanian devil (Sarcophilus harrisii), the world's largest marsupial carnivore, is under threat of extinction following the emergence of an infectious cancer. Devil facial tumour disease (DFTD) is spread between Tasmanian devils during biting. The disease is consistently fatal and devils succumb without developing a protective immune response. The aim of this study was to determine if Tasmanian devils were capable of forming cytotoxic antitumour responses and develop antibodies against DFTD cells and foreign tumour cells. The two Tasmanian devils immunised with irradiated DFTD cells did not form cytotoxic or humoral responses against DFTD cells, even after multiple immunisations. However, following immunisation with xenogenic K562 cells, devils did produce cytotoxic responses and antibodies against this foreign tumour cell line. The cytotoxicity appeared to occur through the activity of natural killer (NK) cells in an antibody dependent manner. Classical NK cell responses, such as innate killing of DFTD and foreign cancer cells, were not observed. Cells with an NK-like phenotype comprised approximately 4 percent of peripheral blood mononuclear cells. The results of this study suggest that Tasmanian devils have NK cells with functional cytotoxic pathways. Although devil NK cells do not directly recognise DFTD cancer cells, the development of antibody dependent cell-mediated cytotoxicity presents a potential pathway to induce cytotoxic responses against the disease. These findings have positive implications for future DFTD vaccine research.
Highlights
The Tasmanian devil (Sarcophilus harrisii), the world’s largest extant marsupial carnivore, is only found on the island of Tasmania, in Australia
The principle mode of devil facial tumour disease (DFTD) transmission is through biting [2], which is common between Tasmanian devils during social interactions such as feeding and mating
To induce anti-tumour responses against DFTD, two healthy captive Tasmanian devils were injected with irradiated DFTD cells and evidence for an immune response was evaluated by testing for anti-DFTD antibodies and cellular cytotoxicity
Summary
The Tasmanian devil (Sarcophilus harrisii), the world’s largest extant marsupial carnivore, is only found on the island of Tasmania, in Australia. Known as devil facial tumour disease (DFTD), has recently emerged within the species. The principle mode of DFTD transmission is through biting [2], which is common between Tasmanian devils during social interactions such as feeding and mating. The cancer establishes as an allograft [2] and the infected devil succumbs to the disease without evidence of an immune response to the tumour [3]. Genetics has shown that DFTD arose from a single original tumour [2,4]. Since the initial immunohistochemical characterisation of DFTD cells by Loh and colleagues [5], DFTD was considered a cancer of neuroectodermal origin. Recent studies on the DFTD transcriptome have established that DFTD was derived from a Schwann cell in a founder animal [4]
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