Researchers from the University of Copenhagen and Sweden’s Karolinska Institutet have discovered how long-lasting killer cells in the skin help defend against intruders and how higher concentrations of these cells in tumour tissue are associated with a higher survival probability for melanoma patients. The study, published in the journal Immunity, found that certain immune T cells called tissue-resident memory cells are formed locally in the skin and other tissues. They protect against infections they have encountered before, and some express proteins that enable them to kill infected cells. The study followed the development of memory killer cells in human skin by isolating T cells from skin and blood of healthy volunteers and then examining gene activity and expression of different proteins. This allowed the researchers to identify T cells in the blood with potential to form memory killer cells in skin or other tissues.
These “memory killer cells” have been shown to respond to immunotherapy, a Nobel Prize-winning cancer therapy involving the activation of the immune system. It is typically used as a complement to other cancer treatments, and there is variation in how patients respond to it. The researchers now aim to use their findings to optimize the immunotherapy-induced T-cell response to better eliminate cancer cells in tissues.
Liv Eidsmo, dermatologist, and professor at the University of Copenhagen in Denmark, and researcher at the Karolinska Institutet, said, “We’ve been able to identify several factors that control the formation of memory killer cells, which play an important part in maintaining healthy skin. There’s a fine balance between effective protection against tumours and infections in the skin and the contribution to inflammatory diseases like vitiligo and psoriasis.” The study was conducted in collaboration with the Karolinska University Hospital, Nordiska Kliniken and Vrinnevi Hospital, and it was financed by grants from Novartis, the EU, KI Foundations and Funds, the Swedish Research Council, the Ragnar Soderberg Foundation, the Swedish Medical Society, Region Stockholm, the Swedish Psoriasis Foundation, the Swedish Dermatology Foundation, the Swedish Cancer Society, the Goran Gustafsson Foundation, Stockholm City Council, the Karolinska Institutet Centre for Innovative Medicine, and the Knut and Alice Wallenberg Foundation.
