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The secrets of natural killer cells: How do they become heroes of the immune system?
Natural Killer Cells (NK cells) are a vital type of cell in the immune system. They are a type of large granular lymphocyte that plays an important role in the innate immune system and can quickly respond to virus-infected cells, tumor cells and other internal pathogens. The impressive capabilities of these cells give them a heroic role in immune defense.
“NK cells act similarly to cytotoxic T cells in vertebrates and can rapidly recognize and destroy infected cells without the need for antibodies or major histocompatibility complex (MHC).”
NK cells can recognize damaged cells that lack MHC I markers and can kill them without prior activation, which allows the immune system to respond in a short period of time to fight potential threats.
This unique recognition mechanism is one of its most important characteristics, and its ability to detect and eliminate tumor cells has been confirmed in a series of studies.
Early History
Since Dr. Henry Smith of the University of Leeds Medical School published the first study on natural immunity produced by unsensitized lymphocytes in 1966, the existence and function of NK cells have gradually been recognized. As research progressed, scientists realized that this type of lymphocyte is specifically responsible for the "natural" cytotoxic response.
"The study showed that cells from this particular population appear to be able to destroy tumor cells without prior induction, in experiments with a variety of species as well as cancer patients."
The name "natural killer cells" reflects this phenomenon and has been widely verified in many studies, such as the use of the K562 cell line, which is a highly cytosolic human NK cell. Lyse the hemophilic target cells.
NK cell types
Based on surface markers, NK cells can be divided into CD56 bright type (CD56bright) and CD56 dark type (CD56dim). CD56 bright NK cells have the property of releasing cytokines, which helps regulate the immune response, while CD56 dark NK cells are mainly responsible for cell killing.
“They are able to eliminate infected cells through CD16-mediated antibody-dependent cell-mediated cytotoxicity (ADCC).”
During the COVID-19 pandemic, different types of NK cells have shown their ability to change between acute and severe cases, providing new insights into the importance of these cells during viral infection.
Receptors and functions
There are a variety of receptors on the surface of NK cells, and the activation and inhibition of these receptors are the key to regulating the function of NK cells. Activating receptors such as natural cytotoxicity receptors (NCRs) directly promote apoptosis, while inhibitory receptors such as killer cell immunoglobulin-like receptors (KIRs) have the function of recognizing MHC I molecules, effectively screening self cells while avoiding Unnecessary cell attacks.
"NK cells can sense the presence of surrounding pathogens and respond quickly, which makes them play an irreplaceable role in the innate immune system."
Prospects for disease prevention and treatment
As scientists gain a deeper understanding of NK cell functions, they hope to apply the properties of these cells to the treatment of diseases such as cancer and HIV. The potential of NK cells in therapy opens up new possibilities for future immunotherapy, and the "memory" function of these cells may even allow them to make stronger immune responses in the event of a secondary infection.
Recent studies have shown that NK cells can form "memory" cells, further revealing their potential role in adaptive immune responses, which is significantly different from traditional cognition.
Conclusion
Through continued research efforts, the mystery of NK cells has been gradually unveiled, revealing their central role in our fight against disease. However, we may discover more secrets about these amazing cells in the future. Could they become a key weapon in the fight against immune system disorders and diseases?
