The Discovery of T Cells and B Cells
July 24, 2026Core Framework & Diagram The Accidental Discovery of NK Cells
July 24, 2026
1 minuete Read
The Accidental Discovery of NK Cells
Your body has a force that shoots without orders
By the Editors 1-min read
In the 1970s, a group of immunologists noticed something that didn't make sense: mice had a type of cell that automatically killed tumor cells without any training, without having ever seen any enemy.
This should not have been possible. Immunological theory at the time clearly stipulated: killing must follow recognition, recognition must follow learning.
But this cell had learned nothing, and it killed anyway.
This accident ultimately gave birth to a completely new cell type — Natural Killer Cells (NK cells) — and a revolution in understanding how the immune system monitors tumors.
KEY TAKEAWAYS
01
NK cells were independently discovered in 1975 by Kiessling and Herberman's teams, overturning immunology's foundational assumption that 'killing must follow learning.'
02
NK cells' working logic is 'missing self': checking whether normal cells' MHC-I identity card is intact. Cells that have lost their protective signal are attack targets — a mechanism specifically countering tumor 'stealth' strategies.
03
NK cells and T cells form complementary double defense: tumor cells can't simultaneously escape both, regardless of MHC-I upregulation or downregulation — an evolutionary double encirclement.
04
NK cells are one of the main forces automatically clearing early cancerous cells daily. Their activity declines with age, but regular exercise (150 minutes per week) can significantly reverse this trend.
05
CAR-NK cell therapy is one of the most active frontiers in tumor immunotherapy; early clinical data shows lower severe side effect risk than CAR-T.
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