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Hemagglutination

Agglutination of red blood cells is called hemagglutination . One common assay that uses hemagglutination is the direct Coombs’ test , also called the direct antihuman globulin test (DAT) , which generally looks for nonagglutinating antibodies. The test can also detect complement attached to red blood cells.

The Coombs’ test is often employed when a newborn has jaundice , yellowing of the skin caused by high blood concentrations of bilirubin, a product of the breakdown of hemoglobin in the blood. The Coombs’ test is used to determine whether the child’s red blood cells have been bound by the mother’s antibodies. These antibodies would activate complement, leading to red blood cell lysis and the subsequent jaundice. Other conditions that can cause positive direct Coombs’ tests include hemolytic transfusion reactions , autoimmune hemolytic anemia , infectious mononucleosis (caused by Epstein-Barr virus ), syphilis , and Mycoplasma pneumonia . A positive direct Coombs’ test may also be seen in some cancers and as an allergic reaction to some drugs (e.g., penicillin).

The antibodies bound to red blood cells in these conditions are most often IgG , and because of the orientation of the antigen-binding sites on IgG and the comparatively large size of a red blood cell, it is unlikely that any visible agglutination will occur. However, the presence of IgG bound to red blood cells can be detected by adding Coombs’ reagent , an antiserum containing antihuman IgG antibodies (that may be combined with anti-complement) ( [link] ). The Coombs’ reagent links the IgG attached to neighboring red blood cells and thus promotes agglutination.

There is also an indirect Coombs’ test known as the indirect antiglobulin test (IAT) . This screens an individual for antibodies against red blood cell antigens (other than the A and B antigens) that are unbound in a patient’s serum ( [link] ). IAT can be used to screen pregnant women for antibodies that may cause hemolytic disease of the newborn . It can also be used prior to giving blood transfusions. More detail on how the IAT is performed is discussed below.

A) Diagram of direct Coomb’s test. 1.  Blood sample from a patient with hemolytic anemia with antibodies attached to red blood cells. 2. Antibodies coat the patient’s red blood cells. 3. A few drops of Coomb’s reagent (containing anti-human antibodies) is mixed in with the patient’s blood sample. 4. Agglutination reaction (clumping) is visible after cross-linkage of antibodies. B) Diagram of indirect Coomb’s test. 1. Patient's serum containing antibodies is drawn. 2. Donor blood is added. 3. Patient's antibodies bind to donor's red blood cells. 4. A few drops of Coombs’ reagent are mixed with the sample. 5. Agglutination reaction is observed.
The steps in direct and indirect Coombs’ tests are shown in the illustration.

Antibodies that bind to red blood cells are not the only cause of hemagglutination. Some viruses also bind to red blood cells, and this binding can cause agglutination when the viruses cross-link the red blood cells. For example, influenza viruses have two different types of viral spikes called neuraminidase (N) and hemagglutinin (H), the latter named for its ability to agglutinate red blood cells (see Viruses ). Thus, we can use red blood cells to detect the presence of influenza virus by direct hemagglutination assays (HA), in which the virus causes visible agglutination of red blood cells. The mumps and rubella viruses can also be detected using HA.

Questions & Answers

write the life cycle of HIV
Firomsa Reply
describe the internal and external structure of prokaryotic cell in terms of there appearance and functions
Lenia Reply
compare and contrast similar structures found in prokaryotic and eukaryotic cells
Lenia
control of microorganisms
ISTEFAZUL Reply
how can a doctor treat a person affected by endospore forming bacteria in his/her wound?
Mambo Reply
a 28 years old woman come to your clinic with complain of fever painful genital blisters which express clear fluid when ruptured burning sensation around the bristers what is the diagnosis?
Ramadhani Reply
genital herpes caused by a virus called herpe simplex virus
Doris
what is the reference between selective medium and differential medium?
Tony Reply
the micro flora of air is transient why
Princess
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essien Reply
welcome essien
Muhammad
welcome essien
Beka
classification of gram positive
lissa Reply
classify gram positive
lissa
catalase test is done to differentiate between staph and strep. as staph is catalase positive while strep is catalase negative then staph is differentiate further on coagulase positive and coagulase negative. staph aureus is coagulase positive while staph epidermidis is coagulase negative.
Muhammad
gram positive staph is further differentiated on sensitivity test and manitol salt fermentation test while gram positive strep is differentiated on hemolysis pattern
Muhammad
more about gramm positive
lissa
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lissa
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Blessing
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Blessing
taxonomy
Rahul
can i use the graph of bacterial growth for my master's thesis?
Christoph Reply
facultative anaerobic bavteria gives uniform turdibity in nutrient broth why?
Princess Reply
oils and waxes are not sterilized in autoclave
Princess
what is the function of paraffin
Muhammad
@ MAHI because they can grow all over the media from surface to the bottom as they can utilize oxygen or conduct fermentation in its absence.
Online
2.@MAHI Autoclave uses steam under pressure. The steam cannot penetrate through oil and wax. Thus, dry heat sterilization is preferred than autoclave .
Online
thnku
Nadiya
how nutirent agar can converted into blood agar
Princess
thank you
Princess
take a nutrient agar ........and add 5ml blood and put in it ...........!
Nadiya
nutrient agar +blood 5ml+ distilled water =blood agar .
Nadiya
mixed wellllll
Nadiya
hi
Rahul
why agar is not a neutrient source?
Shimul
because it's a general purpose agar only use for growing bacteria
Richa
way is antigen
opaleye
what is antigen
opaleye
antigen is a foreign body that cause activation of antibody?
ASNAKE
Antigen is a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.
Shimul
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opaleye
what is pharmacology
Luyenu
a science that studies about the drug
ASNAKE
hello ever one
Sayid
y
Abdul
Work hard
Anigor
y
Abdul
thanks alot
Luyenu
What is the major different between gram positive and gram negative bacteria.
Asikur
bacteria kya hai
Mala
content of their cell wall
Doris
koi mujhse basic microbiology ki study k Lea book suggest kro .
Richa
Harley prescott
Vikas
what are the five predisposing factors of opportunistic infections
Asher Reply
1. long term exposure to diseases, that the body immunity weakens.
prosper
2. Nature Of some diseases to weaken body immunity such as, AIDS.
prosper
3. Use of immuno-suppresive drugs.
prosper
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prosper
Low immune is the major cause eg for kaposis sarcoma
Davismith
suitable conditions e.g temp,
Muhammad
what os gnormal flora
kifayat Reply
morphological and genetic classification of bacteria
Potter Reply
what is the morphogical
Bupe
h
Sudhir
morphologycal is defined as relating to the branch of biology that deals with the form of living organisms,and with relationship between their structures.
Nadiya
relating to the form or structure of things .
Nadiya
what is the meaning of lessions
oluwa
i am frim Afghanistan.
wahidullah Reply
iam from iraq
Haidar
and i'm from pakistan
Muhammad
Nice
Amina
what's about the qualification
Muhammad
Hlo
Asiya
Hmm
Number
Almustafa Muhammad from Nigeria
Mujtafa
am ustaz Abdulsalam from Ghana
ustaz
am Bupe Chifita from Zambia
Bupe
what is microbiology
Bupe
is the study of invisible micro organism
Mujtafa
microbiology is the study of very too small organisms which we can't see with naked eyes ......in other words ....study of microorganism is called microbiology.
Nadiya
Hello! How Can Microorganisms Be Isolated From The Skin?.. 5 ways if possible. (briefly)
prosper
from skin swabbing is the prefer method worldwide
Muhammad
thanks Muhammad Nauman very much!
prosper
hi
Meek
hi Meek
prosper
are there any other ways pals?
prosper
hi prosper
Meek
hello Meek Mild.
prosper
Any question or ideas, Meek?😊
prosper
and if a patient have any blister or abscess on the skin then first cut the blister or abscess. inside material is taking by syringe.
Muhammad
in case of fingernail or toenails simply cut a small piece of nail and culture on the appropriate media at a required temperature and time
Muhammad
Again, thanks Mr. Muhammad! I appreciate the help.
prosper
you welcom prosper 😊
Muhammad
what are the media use for skin swab?
Sieh-Mlanwin
blood and macckonkey mostly usededia for skin bacteria
Muhammad
used media*
Muhammad
@ SIEH mostly fungal infection occurs in skin so SDA ( Sabouraud Dextrose Agar) or MEA ( Malt extract agar) are common.
Online
thanks
Sieh-Mlanwin
Microbiologicam source of vitamins
Bachi Reply
what do you mean?
Md
that's example?
Md
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Muhammad
such as. c/s media
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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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