The human immune system has not been comprehensively understood by scientists. We do know, however, that some of its cells are responsible for defending the body against dangerous bacteria and viruses (type 1 immune response), and others - for defending against parasites such as tapeworms and roundworms (type 2 immune response).

For many years, scientists believed that the type 2 immune response was responsible for creating an environment conducive to the development of cancerous tumours. This is related to the frequent presence of, for example, macrophages involved in this type of immune response. In 2010, ILC2 cells were discovered. ILC2 cells are among the main initiators of this response.

Based on the analysis of scientific papers from recent years, supported by the results of their own research, the Polish-Japanese team of scientists put forward the hypothesis that the role of the type 2 immune response in the development of cancer is not clear.

An example is the anti-cancer activity of ILC2 cells in the context of melanoma, the most malignant form of skin cancer. ILC2 cells activate eosinophils to defend against parasitic worms. The same mechanism that ILC2 use to fight parasites also seems to play a key role in fighting melanoma cells, the scientists explain.

The Polish-Japanese team of scientists used a mouse model of melanoma to investigate the role of ILC2 in the development of cancer. In one of the experiments, the administration of cancer cells together with ILC2 cells resulted in a four times slower tumour development. In some cases, the development of melanoma was inhibited.

'We have discovered that by using appropriate technologies, such as adoptive transfer of ILC2 cells, in the future it would be possible to effectively limit the development of cancerous tumours involving these cells', says Marek Wagner, a biotechnologist from the Innate Immunity Research Group at Łukasiewicz - PORT.

As the authors point out, the anti-cancer role of immune cells participating in the defence against parasites should not come as a surprise. Parasitic diseases themselves may contribute to the development of cancers. The mechanisms of their carcinogenic action are multifactorial and may include mechanical damage to the host tissues caused by the constant movement of parasites through the tissues, and the induction of chronic inflammation associated with this process. For example, schistosomiasis (snail fever) is a parasitic disease caused by parasitic flatworms called schistosomes. Chronic infection with Schistosoma haematobium increases the risk of developing squamous cell carcinoma of the urinary bladder, while the liver flukes Opisthorchis viverrini and Clonorchis sinensis are associated with bile duct cancer. As such, the type 2 immune response, which has evolved over millions of years to combat parasitic infections, could potentially be adapted to fight cancer.

'The publication in +Nature+ is of great importance because it indicates the possibility of developing new anticancer therapies based on the mechanisms of the type 2 immune response, which has so far been considered exclusively as a factor intensifying the development of cancer', Wagner says.

The incidence of melanoma in Poland has increased by 300 percent over the past three decades. Forecasts based on the latest research indicate that by 2040, the number of cases worldwide will increase by 57 percent, and the mortality rate associated with this disease will increase by 68 percent. (PAP)

PAP - Science in Poland, Urszula Kaczorowska

uka/ bar/ amac/