Direct Agglutination, Passive Agglutination And Agglutination Inhibition

Front 1

Precipitaiton

Back 1

- precipitation reactions occur when a SOLUBLE antigen and antibody combine to form an INSOLUBLE complex. Small complexes grow into larger complexes until precipitation can be visualized

Front 2

2 phases of agglutination

Back 2

1) specific binding of antibody to antigen
2) lattice formation. For lattice formation to occur, the antigen must have at least 2 antigenic determinants.

Front 3

Why lattice formation is more rapid in agglutination than in precipitation?

Back 3

because there is an insoluble partilce in the agglutination reactions, fewer antigen-antibody complexes are required to detect the retain.

Front 4

Direct Agglutination

Back 4

a macroscopic clumping can be observed because particulate reagents are used as an indicator of the presence of an antigen-antibody reaction. Naturally occurring antigens on the surface of cells, such as RBCs, or bacteria can be used.

Front 5

Passive Agglutination

Back 5

an inert carrier particle is coated with specific antigen, i.e. antigen is attached to a particle. Particles could be charcoal, latex, gelatin, or RBCs. e.g. rheumatoid factor, rubella antibody, and thyroglobulin antibody assays.

Front 6

Agglutination Inhibition

Back 6

soluble antigen in the patient's sample reacts with known Ab reagent to form an invisible complex: the Ab reagent is then unavailable to react with the particulate antigen reagent; therefore no agglutination means antigen is present in the patient's sample. I

Front 7

Hemagglutination inhibition/ latex agglutination inhibition

Back 7

If RBCs or latex particles are used.

Front 8

Agglutination inhibition positive test

Back 8

there is soluble antigen in patient sample that bind to the specific Ab. Ab cannot bind to particulate antigen reagent ===> no agglutination

Front 9

Agglutination inhibition negative test

Back 9

Ab can bind to the particulate antigen reagent because there is no soluble antigen in the patient sample ===> agglutination

Front 10

In the agglutination tests for Brucellosis:
1) What is the antigen?
2) Is this a direct or passive agglutination technique? How do you know?
3) Why is it important to do this agglutination tests on a patient at 2 week intervals, rather than just a single test?
4) Why is a rising titer (4 fold increase) in this test clinically significant?

Back 10

1)The antigen is a preparation of the killed Brucella
organism
2) This is a direct agglutination technique

Front 11

In the Sure-Vue select Strep A test for grp A Strep:
1) When you remove the dipstick from the reagent kit (i.e., before you have inserted it into the extraction tube) what two things are already in the membrane that allow you to visualize a positive test?
2) Describe the 3 internal controls and their purposes.
3) Describe the 2 external controls and their purposes.

Back 11

1)
2) A red line appearing in the control region (C). It confirms sufficient specimen volume and correct procedural technique. A clear background is an internal negative control. if the test is working properly, the background in the result area should be white to light pink and not interfere with the ability to read the test results.
3) Positive control to make sure all the reagent and non-viable strep A working properly. Negative control to make sure all the reagent working property. It should not be positive because Strep C is used.

Front 12

In the Sure-Vue select Strep A test for group A Streptococcus:
1) What are we looking for in the patient?
2) What is the purpose of the streps 1-3?
3) What is in the bottle labeled "positive control"?
4) What is in the bottle labeled " negative control"?

Back 12

1) presence of Strep grp A
2)
3) non-viable Strep A
4) non - viable strep C