Practical 6: Agglutination and Primary Immunodeficiency

Question 1

What antibody functions are associated with the Fab fragment?

Answer 1

Antigen binding

Question 2

What antibody functions are associated with the Fc fragment

Answer 2

Complement binding

Binding to Fc receptors

Placental transfer

Question 3

In antibody dimers, pentamers etc, what holds the monomers in place?

Answer 3

Disulfide bonds

Question 4

What are the 6 functions of antibodies

Answer 4

Activates complement

Triggers mast cell degranulation

Activates antibody-dependent cellular activity

Causes antigen clumping and inactivation of bacterial toxins

Acts as opsonins

Activates B lymphocytes

Question 5

Antibodies are aglutanins, what does this mean?

Answer 5

They can clump antibodies together

Question 6

What does the constant domain determine?

Answer 6

The classification of the antibody

The functions of the antibody

Question 7

Why is IgM a very effective agglutinin?

Answer 7

It is a pentamer
Valency of ten

Question 8

What is haemagglutination?

Answer 8

The agglutination of red blood cells

Question 9

What are the two main uses of haemoagglutination?

Answer 9

Blood typing

Viral quantification

Question 10

How is blood grouping/typing carried out?
(2)

Answer 10

Use of anti sera (antibodies against certain blood groups)

e.g. agglutination will occur if the anti-sera binds to the erythrocyte i.e. if the anti sera is for the antigen expressed on the rbc

Question 11

What is rheumatoid factor?
(2)

Answer 11

The antibody that was first found in rheumatoid arthritis

An antibody against the Fc portion of IgG

Question 12

How does rheumatoid factor cause arthiris?

Answer 12

This factor binds to the Fc portion of IgG to form immune complexes which contribute to the disease

Question 13

How is a doubling dilution carried out?

Answer 13

Transfer 0.5ml from first tube into the next, then transfer 0.5ml from second tube into third etc

Question 14

What is your control in this experiment?

Answer 14

Only saline - no antibodies (but add the rbcs)
Negative control

Question 15

What should you not do in this experiment?

Answer 15

Don’t vortex - this will lyse the rbcs

Question 16

What does a tight pellet mean?

Answer 16

High agglutination

Question 17

What happens to the pellet as the samples get more dilute?

Answer 17

The pellet diffuses more - lower agglutination

Question 18

What is a primary immunodeficiency?

Answer 18

Disorders that are caused by an inherited flaw in the immune system that increases the susceptibility to infections

Question 19

What are secondary or acquired immmune deficiency disease caused by?

Answer 19

Infectious, chemical or radiological agents

Question 20

Write about chronic granulomatosis disease
(3)

Answer 20

The X-linked form is most common
Causes granulomas (bacteria are ingested by phagocytes but not digested quick enough)

The enzyme that makes the needed chemicals is missing

Question 21

What enzyme is involved in chronic granulomatosis disease?

Answer 21

NADPH oxidase

Question 22

What is NADPH oxidase?
(2)

Answer 22

A complex, multisubunit enzyme

Its coded by a gene on the X chromosome

Question 23

What are the subunits of NADPH oxidase?
(5)

Answer 23

p40phox
p47phox
p67phox
p22phox

gp91phox

Question 24

What subunit is most important to NADPH oxidase?

Answer 24

gp91phox

Question 25

What is phox?

Answer 25

Phagosome oxidase

Question 26

What happens in a respiratory burst?

Answer 26

The cell takes in oxygen

Question 27

Explain how NADPH oxidase works in a healthy cell vs CGD (2)

Answer 27

After respiratory burst all the subunits of NADPH Oxidase should come together to react on the oxygen and form reactive oxygen species to kill the pathogens In CGP there is no/no active gp91phox => no reactive oxygen species can be formed

Question 28

Give two examples of reactive oxygen species

Answer 28

Hydrogen peroxide Super oxide anion

Question 29

Write about leucocyte adhesion deficiency (3)

Answer 29

Leucocytes don't express CD18, no adhesion molecules are expressed, they can't adhere to endothelial cells and get into imflammed tissues This causes gingivitis (inflammation of the gums) Causes omphalitis (inflammation of the umbilical cord)

Question 30

What is inflammation of the umbilical cord called?

Answer 30

Omphalitis

Question 31

What are the four types of adhesion molecules?

Answer 31

Vascular addressin (CD34) (Mucin-like CAM) Selectin (L-selectin) Integrin (LFA-1) Immunoglobulin-like molecule (ICAM-1)

Question 32

What are the steps in the adhesion cascade? (5)

Answer 32

Capture Rolling Activation Adhesion Transmigration

Question 33

How many types of LAD are there?

Answer 33

Three types LAD I, II and III

Question 34

What causes LAD I

Answer 34

Lack of integrins: CD18 Deficiency in B2 integrins

Question 35

What are the symptoms of LAD I (6)

Answer 35

Leukocytosis Bacterial infections Sepsis Gingivitis Omphalitis Bleeding

Question 36

What are the symptoms of LAD II? (6)

Answer 36

Leukocytosis Bacterial infections Sepsis Gingivitis Omphalitis Bleeding

Question 37

What causes LAD II?

Answer 37

Integrin activation

Question 38

What causes LAD III?

Answer 38

Selectins

Question 39

What are the symptoms of LAD III? (4)

Answer 39

Mental retardation Microcephaly Dwarfism Recurrent infections with neutrophils

Question 40

What is XLA?

Answer 40

X-linked agammaglobulineamia

Question 41

What causes XLA?

Answer 41

A deficiency of B cells (BtK)