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The chemokines are chemotactic factors that recruit leukocytes to sites of infection, tissue damage, and inflammation. In contrast to more general chemotactic factors, like complement factor C5a, chemokines are very specific in the subsets of leukocytes they recruit.

Interferons are a diverse group of immune signaling molecules and are especially important in our defense against viruses. Type I interferons (interferon-α and interferon-β) are produced and released by cells infected with virus. These interferons stimulate nearby cells to stop production of mRNA, destroy RNA already produced, and reduce protein synthesis. These cellular changes inhibit viral replication and production of mature virus, slowing the spread of the virus. Type I interferons also stimulate various immune cells involved in viral clearance to more aggressively attack virus-infected cells. Type II interferon (interferon-γ) is an important activator of immune cells ( [link] ).

A cell with viruses inside it releases signals labeled interferons. The interferons travel to 3 different cells. The interferon signals neighboring uninfected cells to destroy RNA and reduce protein synthesis. The interferon signals neighboring infected cells to undergo apoptosis. The interferon also activates immune cells.
Interferons are cytokines released by a cell infected with a virus. Interferon-α and interferon-β signal uninfected neighboring cells to inhibit mRNA synthesis, destroy RNA, and reduce protein synthesis (top arrow). Interferon-α and interferon-β also promote apoptosis in cells infected with the virus (middle arrow). Interferon-γ alerts neighboring immune cells to an attack (bottom arrow). Although interferons do not cure the cell releasing them or other infected cells, which will soon die, their release may prevent additional cells from becoming infected, thus stemming the infection.

Inflammation-eliciting mediators

Many of the chemical mediators discussed in this section contribute in some way to inflammation and fever, which are nonspecific immune responses discussed in more detail in Inflammation and Fever . Cytokines stimulate the production of acute-phase proteins such as C-reactive protein and mannose-binding lectin in the liver. These acute-phase proteins act as opsonins , activating complement cascades through the lectin pathway.

Some cytokines also bind mast cells and basophils , inducing them to release histamine , a proinflammatory compound. Histamine receptors are found on a variety of cells and mediate proinflammatory events, such as bronchoconstriction (tightening of the airways) and smooth muscle contraction.

In addition to histamine, mast cells may release other chemical mediators, such as leukotrienes . Leukotrienes are lipid-based proinflammatory mediators that are produced from the metabolism of arachidonic acid in the cell membrane of leukocytes and tissue cells. Compared with the proinflammatory effects of histamine, those of leukotrienes are more potent and longer lasting. Together, these chemical mediators can induce coughing, vomiting, and diarrhea, which serve to expel pathogens from the body.

Certain cytokines also stimulate the production of prostaglandins , chemical mediators that promote the inflammatory effects of kinins and histamines. Prostaglandins can also help to set the body temperature higher, leading to fever , which promotes the activities of white blood cells and slightly inhibits the growth of pathogenic microbes (see Inflammation and Fever ).

Questions & Answers

write a note of microbiology with definition
Lucky Reply
Microbiology is the study of all living organisms that are too small to be visible with the naked eye. This includes bacteria, archaea, viruses, fungi, prions, protozoa and algae, collectively known as 'microbes'.
si
write down the difference branches of microbiology
Lucky
Baccteriolog: the study of bactera. Immunology: the study of the immune system. It looks at the relationships between pathogens such as bacteria and viruses and their hosts. Mycology: the study of fungi, such as yeasts and molds. Nematology:the study of nematodes (roundworms).
Aashi
Bacteriology: the study of bacteria. Immunology: the study of the immune system. It looks at the relationships between pathogens such as bacteria and viruses and their hosts. Mycology: the study of fungi, such as yeasts and molds. Nematology: the study of nematodes (roundworms).
si
Parasitology :the study of parasites. Phycology: the study of algae. Protozoology : the study of protozoa, single-celled organisms like amoebae. Virology:the study of viruses.
Aashi
Parasitology: the study of parasites. Not all parasites are microorganisms, but many are. Protozoa and bacteria can be parasitic; the study of bacterial parasites is usually categorized as part of bacteriology. Phycology: the study of algae. Protozoology: the study of protozoa, single-celled organis
si
Virology: the study of viruses.
si
all bacterial cells have
Millie Reply
refamycin kills bacterial cell by acting on ...?
Yogesh Reply
monensin kills bacterial cell by acting on
Yogesh
genetic linkage cross over ratio ?
Yogesh
what is microbiology?
onuoha Reply
Hi!!! wants to know the meaning of microbiology
Christian Reply
Microbiology, study of microorganisms, or microbes, a diverse group of generally minute, simple life-forms that include bacteria, archaea, algae, fungi, protozoa, and viruses. The field is concerned with the structure, function, and classification of such organisms .
si
to study the life of microorganisms or microbes by knowing their characteristics types and relative species in lab
ayesha
Microbiology is simply the study of microbial world.
Shyamji
Microbiology is the branch of biology in which we study microorganisms those which cannot be seen with naked eye these are bacteria,fungi,viruses Protozoa etc.
Nisar
thanks for that information
Better
microbiology, is a study of microorganisms adiversegroup of generally, simple life,
Better
Thanks ever so much for the discussion.
Christian
Can anyone help with Organic Chemistry, and types?
Christian
which topic in organic chemistry
si
Introduction to organic chemistry.
Christian
Organic chemistry is the chemistry of carbon, an element that forms strong chemical bonds to other carbon atoms as well as to many other elements like hydrogen, oxygen, nitrogen, and the halogens. ... Many are composed of only carbon and hydrogen, collectively called hydrocarbons.
si
microbiology is the study of microorganisms like (bacteria ,viruses,fungi,protozoa and algae) their relationship to environment and their impact on environment .
TASAWAR
can one tell me what are reservoirs and their types with explanation.
onuoha
structure of protists
Rayyanu Reply
what is enzyme engineering
swati Reply
what is the difference between prokaryotes and eukaryotes?
Guirlaine Reply
Prokaryotes lack nucleus in their cells while eukaryotes have well defined nucleus in their cells
Ayo
Prokaryotes are organisms that consist of a single prokaryotic cell. Eukaryotic cells are found in plants, animals, fungi, and protists. They range from 10–100 μm in diameter, and their DNA is contained within a membrane-bound nucleus. Eukaryotes are organisms containing eukaryotic cells.
Pratibha
The Day Jimmy"s Boa Ate the Wash by TRINKA HAKES NOBLE pictures by STEVEN KELLOGG
Alexia Reply
cytoplasmic membrane system in eukaryotes is called
Myerlyn Reply
I study in French,but I guess it's the same: we call it as the procaryotes "cytoplasme" but it's structure "cytosquelette" hope I helped.
BENNINI
hi bennini , I studied in English but I want to pursue in French .could u plz help me with French .thanks in advance
si
hi Si Yo, yes,of course how can I help you?
BENNINI
here can I download it where I could study it with relax dear
Irfan
hi
Ruth
ok
Francis
meaning of contagium vivum?
Royce Reply
explain transglutaminase cycle ?
Dilsath Reply
what a tropism in host
Khaliil Reply
HPV vaccine given to school children
Jayani Reply
Differentiation between electron, proton and neutron
Zainab Reply
proton .possitive charge electron . negative charge neutron . having no charge
Kifayat
proton positive charge. electron negative charge. And no charge of the neutron.
Saman
the nucleus is composed of electrons (-) charge and they turn around the Nucleon the Nucleon = neutron(no charge) + proton (+) a neutron can turn to a proton and vice versa (cuz they have the same mass=1)
BENNINI
Practice MCQ 5

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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