Question

How do natural killer cells differ from macrophages?

Answer 1

Hint: Natural killer cells and macrophages are the cells of the immune system of our body. The immune system is made up of many different types of white blood cells, and organs that help us to stay healthy and fight infection. Natural killer cells and macrophages play a vital role in this process.

Complete answer:
-Natural killer cells are a part of the lymphoid lineage of blood cells. These cells are large granular lymphocytes that represent circulating lymphocytes in our blood. The natural killer cell looks at the abnormality in self-cells by looking at the surface molecules. The major function of the NK cells is to eliminate the infected or cells in distress through various pathways including the normal cell killing function and the release of cytokines. The body responds to viruses by secreting cytokines that disrupt viral replication and make cells more susceptible to attack by NK cells.
-NK cells release the primary cytokine as a type of II interferon which activates macrophages.
The IL macrophage secretion - and the type II interferon of NK cell secretion create positive feedback that increases and activates both types of cells within the tissues.
-These processes enhance the effect of NK cells and prevent the virus infection from spreading. The macrophage development by type II interferon activates and leads to release of cytokines of T cells. This activation of T cells starts the adaptive immune response and inhibits the functions of NK cells allowing the cytotoxic T cells to take over.
-An important characteristic of NK cells is their ability to differentiate between normal and virus prone cells. One mechanism, in particular, is mediated by inhibitory receptors specific for MHC class I molecules, which inhibit cell killing. Virus-prone cells typically down-regulate MHC class expression, therefore the infected cell is susceptible to NK- mediated cell killing.
-Macrophages are a part of the myeloid lineage of blood cells. They differ from monocytes in the blood and travel to the tissue where they become macrophages. They are large, irregularly shaped cells with a large cytoplasm and numerous vacuoles. Macrophages provide the first line of defence in the innate immune response to pathogens. They engulf material (phagocytosis) and eliminate debris.
-Also they release biologically active proteins called cytokines and recruit other immune system cells to stop the infection from spreading. These cells have several different receptors on their surface which help to identify and bind pathogens to promote phagocytosis and stimulate the release of cytokines.

Note: The receptors include IL-, IL-, CXCL, IL-, and TNF-a. The inflammatory cytokines released by the macrophages can stimulate the effects at the site of infection and throughout the body.
Examples of the effects of inflammatory cytokines are the recruitment of neutrophils to the side of infection by CXCL and activation of NK cells by IL-.
Natural Killer cells (NK) and macrophages play a major role in the clearance of senescent cells, and produce cytokines that activate macrophages that remove senescent cells.