Researchers, including one of Indian origin, have found that high expression of a cell-signalling molecule, known as interleukin-9, in immune cells inhibits melanoma growth.

After observing mice without genes responsible for development of an immune cell called T helper cell 17 (TH17), the researchers from Brigham and Women’s Hospital (BWH) found that these mice had significant resistance to melanoma tumour growth, suggesting that blockade of the TH17 cell pathway favoured tumour inhibition. The researchers also noticed that the mice expressed high amounts of interleukin-9.

"These were unexpected results, which led us to examine a possible contribution of interleukin-9 to cancer growth suppression.” Rahul Purwar said.

The researchers next treated melanoma-bearing mice with T helper cell 9 (TH9), an immune cell that produces interleukin-9. They saw that these mice also had a profound resistance to melanoma growth. This is the first reported finding showing an anti-tumour effect of TH9 cells.

Moreover, the researchers were able to detect TH9 cells in both normal human blood and skin, specifically in skin-resident memory T cells and memory T cells in peripheral blood mononuclear cells. In contrast, TH9 cells were either absent or present at very low levels in human melanoma. This new finding paves the way for future studies that will assess the role of interleukin-9 and TH9 cells in human cancer therapy.

Melanoma is the most dangerous form of skin cancer. It is curable if recognized and treated early. The study has been published online in Nature Medicine.

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