The cell-mediated innate immune system comprises various components that act rapidly and non-specifically to defend the host against invading pathogens. Key cells include:
Natural killer (NK) cells are cytotoxic lymphocytes that play a crucial role in recognizing and eliminating infected or abnormal cells. They can directly induce apoptosis (programmed cell death) in target cells and participate in the defense against viruses and certain types of cancer.
Macrophages and neutrophils are phagocytic cells that engulf and digest pathogens. Macrophages, found in tissues, are long-lived and contribute to both innate and adaptive immunity. Neutrophils are short-lived but are the first responders to infections, migrating quickly to sites of inflammation.
Dendritic cells are antigen-presenting cells that capture, process, and present antigens to T cells. They play a crucial role in initiating adaptive immune responses by activating T cells when they encounter pathogens.
Gamma-delta T cells are a subset of T lymphocytes that bridge the gap between the innate and adaptive immune systems. They recognize antigens in a manner similar to innate immune cells and can respond rapidly to infections, providing a quick immune defense.
Granulocytes (neutrophils, mast cells*, basophils, and eosinophils) play a crucial role in the innate immune response by detecting and combating pathogens through mechanisms such as phagocytosis, release of inflammatory mediators, and regulation of immune reactions.
*Note: Mast cell designation as a granulocyte is technically inaccurate due to developmental differences between mast cells and other granulocytes. Mast cells have granule content that overlaps with basophil granule content (example: histamine).
Innate lymphoid cells (ILCs) are a diverse group of immune cells that lack antigen-specific receptors. They are involved in the early immune response against pathogens, contributing to tissue repair, inflammation, and defense against infections.
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Source: ChatGPT response prompted and edited by Joel Graff.
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