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  • If a patient's blood agglutinates with anti-B serum, what is the patient’s blood type?
  • What is a cross-match assay, and why is it performed?

[link] summarizes the various kinds of agglutination assays discussed in this section.

Mechanisms of Select Antibody-Antigen Assays
Type of Assay Mechanism Example
Agglutination Direct: Antibody is used to clump bacterial cells or other large structures Serotyping bacteria
Indirect: Latex beads are coupled with antigen or antibody to look for antibody or antigen, respectively, in patient serum Confirming the presence of rheumatoid factor (IgM-binding Ig) in patient serum
Hemagglutination Direct: Some bacteria and viruses cross-link red blood cells and clump them together Diagnosing influenza, mumps, and measles
Direct Coombs’ test (DAT): Detects nonagglutinating antibodies or complement proteins on red blood cells in vivo Checking for maternal antibodies binding to neonatal red blood cells
Indirect Coombs’ test (IAT): 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 in vitro Performing pretransfusion blood testing
Viral hemagglutination inhibition: Uses antibodies from a patient to inhibit viral agglutination Diagnosing various viral diseases by the presence of patient antibodies against the virus
Blood typing and cross-matching: Detects ABO, Rh, and minor antigens in the blood Matches donor blood to recipient immune requirements

Key concepts and summary

  • Antibodies can agglutinate cells or large particles into a visible matrix. Agglutination tests are often done on cards or in microtiter plates that allow multiple reactions to take place side by side using small volumes of reagents.
  • Using antisera against certain proteins allows identification of serovars within species of bacteria.
  • Detecting antibodies against a pathogen can be a powerful tool for diagnosing disease, but there is a period of time before patients go through seroconversion and the level of antibodies becomes detectable.
  • Agglutination of latex beads in indirect agglutination assays can be used to detect the presence of specific antigens or specific antibodies in patient serum.
  • The presence of some antibacterial and antiviral antibodies can be confirmed by the use of the direct Coombs’ test , which uses Coombs’ reagent to cross-link antibodies bound to red blood cells and facilitate hemagglutination .
  • Some viruses and bacteria will bind and agglutinate red blood cells; this interaction is the basis of the direct hemagglutination assay , most often used to determine the titer of virus in solution.
  • Neutralization assays quantify the level of virus-specific antibody by measuring the decrease in hemagglutination observed after mixing patient serum with a standardized amount of virus.
  • Hemagglutination assays are also used to screen and cross-match donor and recipient blood to ensure that the transfusion recipient does not have antibodies to antigens in the donated blood.

Fill in the blank

In the major cross-match, we mix ________ with the donor red blood cells and look for agglutination.

patient serum

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Coombs’ reagent is an antiserum with antibodies that bind to human ________.

immunoglobulins/antibodies and/or complement

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Short answer

Explain why the titer of a direct hemagglutination assay is the highest dilution that still causes hemagglutination, whereas in the viral hemagglutination inhibition assay, the titer is the highest dilution at which hemagglutination is not observed.

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Why would a doctor order a direct Coombs’ test when a baby is born with jaundice?

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Questions & Answers

what is the size of virus
Beatrice Reply
What is the difference between TVC and Bioburden test
Mohamed
?
Mohamed
structure of bacteria and 10 types
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Ikpi
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mohamed
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Blessing
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Swami Reply
yes
sildra
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sildra
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Manya
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sildra
non living matters like stones? rocks?
Manya
eno
sildra
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sildra
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Manya
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Hi
Maruf
Family kindly help me with this question? 1) Shortlist the configurative measurements of the following human anatomical ranges of÷ - Blood ( haemeglobin) in both male and female - Haematocytes in both male and female - Hepatocytes in both male and female - Lymphocyte / T. Lymphocytes in both male
Gifted
My names are Gift Mwale and am a Zambian. Kindly help me with this research which goes like this... 1) Shortlist the configurative measurements of the following human anatomical ranges of ÷ - Blood ( haemeglobin) in both male and female - Hepatocytes in both male and female - Haematocytes in both
Gifted
please what is the full meaning for TCDS
UDEME
from a single cell
Freedom
tcds means transcranial direct current stimulation...in this small electric currents are given to brain( specific parts) to help increase brain performance or to help with depression.. current should be in range 0.5-2.0mA
Manya
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feven
please can anybody talk about brain tumour and its cure.
BELLO Reply
enlargement of the thyroid gland resulting in over production of hormone.
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What can u say on Thyroid Cancer?
Abdulkareem
Please, talk about the thyroid cancer.
BELLO
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is unit of life
Kamaluddeen
Ok
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It contains peptidoglcon, DNA nd RNA
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Ikpi
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disease due to __________ abnormalities are termed primary immunodeficiencies
Tayee Reply
Some primary immunodeficiencies are due to a defect of a single cellular or humoral component of the immune system.
Prince
Examples of primary immunodeficiencies include: chronic granulomatous disease, X-linked agammaglobulinemia, selective IgA deficiency etc
Prince
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Nana
explain microbial mutation
Emerald
what is mutation
Cynthia Reply
alteration in genetic makeup
UDEME

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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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