Natural Killer (NK) Cells Also Have a Memory Function; Study Shows One Third of NK Cells in Liver Have Antigen Specificity; These Antigen-Specific NK Cells Also Exhibit Unique Gene Expression Profile

Researchers from MedUni Vienna's Departments of Dermatology and Surgery in Austria have managed to ascribe an immunological memory function to a subset of cytotoxic natural killer (NK) cells, which have hitherto been regarded as antigen-non-specific. The researchers found, under the leadership of Georg Stary, MD, PhD, who is also Co-Director of the Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases and affiliated with the CeMM (Research Center for Molecular Medicine of the Austrian Academy of Sciences), that approximately one third of all human liver NK cells can remember viruses and therefore respond specifically to them. These cells are therefore an interesting target for prophylactic use in the human immune system in the fight against infections and viruses. NK cells are natural cytotoxic killer cells in human blood and are a type of lymphocyte, a subgroup of white blood cells or leukocytes. They are able to identify and kill abnormal cells such as tumor cells or virally infected cells (apoptosis). Up until now, NK cells have been regarded as having no memory function, meaning that they are unable to kill on an "antigen-specific" basis but are only able to react afresh each time to viruses and sources of infection in a non-specific way. In the new study, published online on October 2, 2020 in Science Immunology, the MedUni Vienna scientists reported that that there is a subset of NK cells in the liver--the organ which is generally regarded as a large reservoir for NK cells--that is able to fight infections such as hepatitis A and B and to remember them. This subset also exhibits a unique gene expression profile that is different from that of other NK cell groups. The Science Immunology article is titled “A Discrete Subset of Epigenetically Primed Human NK Cells Mediates Antigen-Specific Immune Responses.”
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