Researchers assign immunological memory function to cytotoxic natural killer cells

A new study by researchers from the Departments of Dermatology and Surgery at the Medical University of Vienna could prove beneficial for the human immune system.

Image Credit: Medical University of Vienna

They have successfully assigned an immunological memory function to a subset of cytotoxic natural killer (NK) cells, which have so far been considered as antigen-non-specific.

Led by Georg Stary, who is also Co-Director of the Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases and associated with the CeMM (Research Center for Molecular Medicine of the Austrian Academy of Sciences), the team identified that about one-third of all human liver NK cells can recall viruses and thus respond particularly to them.

These cells thus serve as an interesting target for prophylactic use in the human immune system to combat viruses and infections.

NK cells are natural cytotoxic killer cells present in human blood and are a kind of lymphocyte, which is a subgroup of leukocytes or white blood cells. NK cells are capable of identifying and destroying abnormal cells like virally infected cells (apoptosis) or tumor cells.

To date, NK cells have been considered as lacking memory function, that is, they cannot kill on an “antigen-specific” basis and are only able to react afresh every time to viruses and sources of infection in a non-specific manner.

As part of a study published recently in the Science Immunology journal, the team from the Medical University of Vienna identified that there is a subset of NK cells present in the liver—the organ generally considered as a large pool for NK cells—that is able to combat infections like hepatitis A and B and to remember them. This subset also displays an exclusive gene expression profile that differs from that of other groups of NK cells.

Our study results show that this particular subset of NK cells mediates effective antigen-specific processes. This subset of NK cells could therefore be a suitable candidate for specific, therapeutic and also prophylactic vaccination strategies.”

Georg Stary, Co-Director, Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases

The blood of healthy people contains about 5%–15% of NK cells, where the liver serves as a reservoir for these cells.

The next step for the authors in their study is to examine the function of the NK cells in the course of infectious diseases. Moreover, they wish to find if these NK cells also take over missing memory functions in patients with unusual diseases with immunodeficiencies affecting B and T lymphocytes.