Technical Articles

The human immune system serves as a critical defense against pathogens and abnormal cells. Among its components, natural killer (NK) cells—key players in innate immunity—can directly eliminate senescent, damaged, and cancerous cells without requiring antigen recognition, positioning them as the "first line of defense" in anti-tumor immune responses.

MHC class I molecules present endogenous antigen-derived peptides. They display short peptides (8 - 11 amino acids long) from the cytoplasm, like viral or tumor - related ones, to cytotoxic T lymphocytes (CTLs).

Natural Killer (NK) cells are a critical component of the innate immune system, constituting approximately 15% of all circulating lymphocytes. Unlike T cells and B cells, NK cells can directly recognize and eliminate tumor cells and virus-infected cells without prior sensitization. They exert their potent anti-tumor and anti-viral functions primarily through the release of cytotoxic substances such as perforin and granzymes, as well as the production of cytokines like IFN-γ and TNF-α.

The mononuclear phagocyte system comprises monocytes in the blood and fixed or mobile macrophages in tissues, which possess phagocytic functions. Dendritic cells (DCs) are named for their numerous dendritic or pseudopod-like protrusions upon maturation. Natural Killer (NK) cells primarily originate from the bone marrow, where they gradually mature within the bone marrow microenvironment before distributing into the peripheral blood.