What is the Origin of Natural Killer Cells?

The term arose from the observation that these lymphocytes could spontaneously kill certain cancer and virus-infected cells in culture without needing to be "primed" by specific antigens, a property distinct from T and B lymphocytes. They are derived from the common lymphoid progenitor cell line in the bone marrow. This discovery established a new category of immune defense.

What is the Mechanism of Natural Killer Cells?

NK cells identify compromised cells through a complex system of activating and inhibitory receptors that recognize surface molecules on target cells, such as MHC class I. When inhibitory signals are lost or activating signals are dominant, the NK cell releases perforin and granzymes, which induce apoptosis in the target cell. Their activity is profoundly influenced by circulating hormones and chronic stress levels, linking the endocrine system directly to immune competence and surveillance.

Natural Killer Cells

Meaning

A type of cytotoxic lymphocyte that plays a critical role in the innate immune system, providing rapid responses to virus-infected cells and tumor formation. These cells are essential for immune surveillance and are capable of killing target cells without prior sensitization. They represent a key, non-specific line of defense.