Diseases, Conditions, Syndromes

Lung neuropeptide exacerbates lethal influenza virus infection

Severe influenza virus infection is characterized by a strong inflammatory response and profuse viral replication in lungs. These viruses, such as the notorious avian flu, have a high rate of death and to date there are no ...

Neuroscience

Two for the price of one

Mononuclear phagocytes can both promote and inhibit inflammation. An LMU team has now shown that individual phagocytes in the central nervous system can play both roles, sequentially adopting different phenotypes with distinct ...

Immunology

Cell death in gut implicated in bowel disease

The natural life cycle of cells that line the intestine is critical to preserving stable conditions in the gut, according to new research led by a Weill Cornell Medicine investigator. The findings may lead to the development ...

Immunology

M-CSF plays role in host defense in bacterial pneumonia

(HealthDay)—The cytokine M-CSF promotes survival of lung and liver mononuclear phagocytes to mediate host defense during bacterial pneumonia, according to an experimental study published in the June 15 issue of The Journal ...

Medical research

Potential way to control cholesterol levels via dying cells

A discovery about how the body deals with the cholesterol contained within its dying cells has suggested an exciting new approach to control people's cholesterol levels – and thus their risk of developing heart disease.

Diseases, Conditions, Syndromes

Defense against bacterial infection in chronic granulomatous disease

Deletion of a protein in white blood cells improves their ability to fight the bacteria staphylococcus aureus and possibly other infections in mice with chronic granulomatous disease (CGD), according to a National Institutes ...

Medical research

'WAVE1' identified as key protein in sepsis

Sepsis is a feared complication in bacterial infections. Despite treatment with antibiotics this uncontrolled systemic inflammation is linked to a very high mortality rate because there is no treatment that could bring the ...

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Phagocyte

Phagocytes are the white blood cells that protect the body by ingesting (phagocytosing) harmful foreign particles, bacteria, and dead or dying cells. Their name comes from the Greek phagein, "to eat" or "devour", and "-cyte", the suffix in biology denoting "cell", from the Greek kutos, "hollow vessel". They are essential for fighting infections and for subsequent immunity. Phagocytes are important throughout the animal kingdom and are highly developed within vertebrates. One litre of human blood contains about six billion phagocytes. Phagocytes were first discovered in 1882 by Ilya Ilyich Mechnikov while he was studying starfish larvae. Mechnikov was awarded the 1908 Nobel Prize in Physiology or Medicine for his discovery. Phagocytes occur in many species; some amoebae behave like macrophage phagocytes, which suggests that phagocytes appeared early in the evolution of life.

Phagocytes of humans and other animals are called "professional" or "non-professional" depending on how effective they are at phagocytosis. The professional phagocytes include cells called neutrophils, monocytes, macrophages, dendritic cells, and mast cells. The main difference between professional and non-professional phagocytes is that the professional phagocytes have molecules called receptors on their surfaces that can detect harmful objects, such as bacteria, that are not normally found in the body. Phagocytes are crucial in fighting infections, as well as in maintaining healthy tissues by removing dead and dying cells that have reached the end of their lifespan.

During an infection, chemical signals attract phagocytes to places where the pathogen has invaded the body. These chemicals may come from bacteria or from other phagocytes already present. The phagocytes move by a method called chemotaxis. When phagocytes come into contact with bacteria, the receptors on the phagocyte's surface will bind to them. This binding will lead to the engulfing of the bacteria by the phagocyte. Some phagocytes kill the ingested pathogen with oxidants and nitric oxide. After phagocytosis, macrophages and dendritic cells can also participate in antigen presentation, a process in which a phagocyte moves parts of the ingested material back to its surface. This material is then displayed to other cells of the immune system. Some phagocytes then travel to the body's lymph nodes and display the material to white blood cells called lymphocytes. This process is important in building immunity. However, many pathogens have evolved methods to evade attacks by phagocytes.

This text uses material from Wikipedia, licensed under CC BY-SA