Practice #2

Question 1

Ag binding site of an Ab determines the _________ of the Ab

Answer 1

Idiotype

Question 2

Constant region of the Ab determines the __________ of the Ab

Answer 2

Isotype

Question 3

IgA

Answer 3

Monomeric, dimeric or trimeric Found mainly along mucous membranes but also on the blood in small amount

Question 4

IgD

Answer 4

Monomeric Antigen receptor on naive B cells Role in activation of basophils, mast cells

Question 5

IgE

Answer 5

Monomeric Role in allergic reactions and antiparasitic immunity

Question 6

IgG

Answer 6

Monomeric Mainly in the blood Can cross the placenta

Question 7

IgM

Answer 7

Pentameric or monomeric as BCR Primary antibody response

Question 8

What are the different Ig concentrations in the serum

Answer 8

IgG 12mg/ml IgA 2.1 IgM 1.5 IgD 0.04 IgE 0.00003

Question 9

Ab-Ag possible bonds

Answer 9

1. Hydrogen 2. Ionic 3. Van der Waals 4. Hydrophobic interactions NOT covalent

Question 10

Affinity of Ab-Ag binding

Answer 10

The strength of the Ab-Ag bonds Ex IgG after affinity maturation has higheraffinity for the Ag then IgM

Question 11

Avidity of Ab-Ag binding

Answer 11

The overall strength of binding is higher Depends on the number of possible bonds (valency) or if it can bind more then 1 epitope on the antigen (polyvalent) Ex IgM is a pentamer with 10 Ag binding sites that can bind different (similar) epitopes on the antigen hence its avidity is higher then that of IgG

Question 12

Single radial immunodiffusion assay (MANCINI)

Answer 12

1. Plate of agarose gel with polyclonal antibodies 2. Holes inside the gel contains blood serum from the pt 3. Incubation 4. Ag from the serum diffuse into the gel and form immune complexes in the equilibrium point between the Ag:Ab and the diffusion will stop 5. We can measure the concentration of complement proteins in the serum that way (linear relationship)

Question 13

Two dimentional single immunodiffusion assay (MANCINI)

Answer 13

The same process like the single radial MANCINI just now we check not only the Ag concentration but also the Ab concentration. The set up is exectly the opposite. Antigens in the agar plate and Ab from the serum will diffuse out of the hole.

Question 14

Methods for detection of the antibody as a protein

Answer 14

1. MANCINI 2. Electrophoresis 3. Precipitation Agglutination tests 4. Immunofixation

Question 15

Serum (zone) electrophoresis

Answer 15

Detection of the constitution of blood plasma proteins (globulins and albumin) Sepration by electrophoresis and dye by Coomassie blue From negative to positive: gamma globulins beta globulins alpha2 globulins alpha1 globulins (fewer in num) albumin (highest in num)

Question 16

Densitogram

Answer 16

Normal

Question 17

Densitogram

Answer 17

Chronic liver disease

(hepatitis)

Question 18

Densitogram

Answer 18

Multiplex myeloma

Question 19

Densitogram

Answer 19

Polyclonal gammopathy

(normal immune rsponse)

Question 20

What is the meaninng of the M spike in MM densitogram

Answer 20

Production of multiple monoclonal antibodies

Question 21

What are the indications for electrophoresis?

Answer 21

1. to detect paraproteins or misfolded proteins
2. to detect protein deficiencies
3. to measure relative conc of serum proteins

Question 22

Esterase reaction

With and without NaF

Answer 22

1. Synthetic substrate is entered to a WBC
2. Leukocyte esterase converts it to naphtol
3. Insertion of diazonium
4. Diazonium reacts with naphtol to form a brown product

In the presence of NaF, leukocyte esterase will be inhibited in megakaryocytes, platelets, plasma cells and monocytes but not in lymmphocytes and granulocytes

Question 23

Immune complex definition

Answer 23

Soluble Ag-Ab complex

Question 24

Methods used to measure the conc of immune complexes

Answer 24

1. Turbidimetry: intensity of transmitted light

sensitivity threshold 50micog/ml

2. Nephelometry: intensity of scattered light

sensitivity threshold 1microg/ml

Question 25

Precipitate

Answer 25

Insoluble aggregates of Abs and Ags

when there is equilibrium between Ab and Ag

Question 26

Precipitation depends on

Answer 26

1. valency
2. temperature
3. salt conc
4. pH
5. time

Question 27

Immunofixation assay

Answer 27

For the detection of a particular Ab isotype

The sample can be any body fluid

placed on a plate with specific antibodies for different Ab isotypes

The complex is fixed and stained

Question 28

Immunofixation test in MM will find

Answer 28

IgG kappa or lambda light chains in the urine

Bence Jones proteins

Question 29

Agglutination

Answer 29

Clumping that occurs due to binding of Ab and Ag of corpuscular nature

Ex: RBC, WBC, bacteria, latex

Question 30

Agglutinins

Answer 30

Ab causing agglutination mainly pentameric IgM

Question 31

Active agglutination

• direct
• indirect

Answer 31

The particle contributes to the reaction with its own Ag

• Direct: binding of 1Ab is enough for agglutination
• Indirect: secondart antibodies are needed for agglutination

Question 32

Passive agglutination

Answer 32

The particle serves as a carrier for the Ag or hapten to which the Ab binds

Question 33

Positive agglutination reaction

Answer 33

Equivalence between Ag-Ab

slow sedimentation

Question 34

Antibody titer

Answer 34

The highest degree of dilution where hemagglutination still occurs

1. no infection
2. acute infection
3. repeated infection
4. immune suppression
5. defense
6. asymptomatioc infection

Question 35

Passive agglutination tests

Answer 35

1. Antigen is attached to latex beads and the presence of Ab is detected
2. Ab are attached to latex beads and the presence of Ag is detected

Applications: test for meningitis capsular Ag, RF