Practical 6: Agglutination and Primary Immunodeficiency Flashcards
What antibody functions are associated with the Fab fragment?
Antigen binding
What antibody functions are associated with the Fc fragment
Complement binding
Binding to Fc receptors
Placental transfer
In antibody dimers, pentamers etc, what holds the monomers in place?
Disulfide bonds
What are the 6 functions of antibodies
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
Antibodies are aglutanins, what does this mean?
They can clump antibodies together
What does the constant domain determine?
The classification of the antibody
The functions of the antibody
Why is IgM a very effective agglutinin?
It is a pentamer
Valency of ten
What is haemagglutination?
The agglutination of red blood cells
What are the two main uses of haemoagglutination?
Blood typing
Viral quantification
How is blood grouping/typing carried out?
(2)
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
What is rheumatoid factor?
(2)
The antibody that was first found in rheumatoid arthritis
An antibody against the Fc portion of IgG
How does rheumatoid factor cause arthiris?
This factor binds to the Fc portion of IgG to form immune complexes which contribute to the disease
How is a doubling dilution carried out?
Transfer 0.5ml from first tube into the next, then transfer 0.5ml from second tube into third etc
What is your control in this experiment?
Only saline - no antibodies (but add the rbcs)
Negative control
What should you not do in this experiment?
Don’t vortex - this will lyse the rbcs
What does a tight pellet mean?
High agglutination
What happens to the pellet as the samples get more dilute?
The pellet diffuses more - lower agglutination
What is a primary immunodeficiency?
Disorders that are caused by an inherited flaw in the immune system that increases the susceptibility to infections
What are secondary or acquired immmune deficiency disease caused by?
Infectious, chemical or radiological agents
Write about chronic granulomatosis disease
(3)
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
What enzyme is involved in chronic granulomatosis disease?
NADPH oxidase
What is NADPH oxidase?
(2)
A complex, multisubunit enzyme
Its coded by a gene on the X chromosome
What are the subunits of NADPH oxidase?
(5)
p40phox
p47phox
p67phox
p22phox
gp91phox
What subunit is most important to NADPH oxidase?
gp91phox
What is phox?
Phagosome oxidase
What happens in a respiratory burst?
The cell takes in oxygen
Explain how NADPH oxidase works in a healthy cell vs CGD
(2)
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
Give two examples of reactive oxygen species
Hydrogen peroxide
Super oxide anion
Write about leucocyte adhesion deficiency
(3)
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)
What is inflammation of the umbilical cord called?
Omphalitis
What are the four types of adhesion molecules?
Vascular addressin (CD34) (Mucin-like CAM)
Selectin (L-selectin)
Integrin (LFA-1)
Immunoglobulin-like molecule (ICAM-1)
What are the steps in the adhesion cascade?
(5)
Capture
Rolling
Activation
Adhesion
Transmigration
How many types of LAD are there?
Three types LAD I, II and III
What causes LAD I
Lack of integrins: CD18
Deficiency in B2 integrins
What are the symptoms of LAD I
(6)
Leukocytosis
Bacterial infections
Sepsis
Gingivitis
Omphalitis
Bleeding
What are the symptoms of LAD II?
(6)
Leukocytosis
Bacterial infections
Sepsis
Gingivitis
Omphalitis
Bleeding
What causes LAD II?
Integrin activation
What causes LAD III?
Selectins
What are the symptoms of LAD III?
(4)
Mental retardation
Microcephaly
Dwarfism
Recurrent infections with neutrophils
What is XLA?
X-linked agammaglobulineamia
What causes XLA?
A deficiency of B cells (BtK)
