PBL3

Question 1

what does IgA do

Answer 1

Mucosal areas, such as gut, respiratory tract and urogenital tract. Prevents colonization by pathogens. Also in saliva, tears, and breast milk.

Question 2

what does IgD do

Answer 2

Functions mainly as an antigen receptor on B cells that have not been exposed to antigens. Shown to activate basophils and mast cells to produce antimicrobial factors.

Question 3

What does IgE do

Answer 3

Binds to allergens and triggers histamine release from mast cells and basophils, and is involved
in allergy. Protects against parasitic worms.

Question 4

what does IgG do

Answer 4

Provides the majority of antibody-based immunity against invading pathogens. Only antibody capable of crossing the placenta to give passive immunity to the fetus.

Question 5

What does IgM do

Answer 5

Expressed on the surface of B cells (monomer) and in a secreted form (pentamer) with very high avidity. Eliminates pathogens in early stages of B cell-mediated (humoral) immunity before there is sufficient IgG.

Question 6

what do antibodies do

Answer 6

• agglutination
• neutralisation
• complement
• antibody dependent killing cells
• opsinization

Question 7

what is IgG able to do

Answer 7

– Provides passive immunity for up to 1st 6 months of life

– IgG long half life in serum (~month) sequestered in liver and endothelial cells

Question 8

What does IgA do

Answer 8

IgA is in breast milk

– Ambrose breast fed provides some immunity

Question 9

what causes the long half life of IgG

Answer 9

Neonatal Fc receptor (FcRN) contributes to long half life of IgG
• Similar in structure to MHC class I molecules
• Found in the placenta and helps facilitate transport of mother’s IgG to fetus
• Receptor also plays a role in salvage of IgG in adults through its role in endocytosis in endothelial cells.
– Fc receptors in acidic endosomes bind to IgG internalized through pinocytosis, releasing it into the basic pH of blood
– Prevents it from undergoing lysosomal degradation

Question 10

describe X linked agammaglobulinemia

Answer 10

• X-linked recessive
– Approx 1:100,000 -1:300,000 • Extremely rare in females
• Life expectancy 40+ years

Question 11

What are the symptoms of X linked agammaglobulinemia

Answer 11

History of recurrent infections, mostly in respiratory tract
– Increased susceptibility to encapsulated pyogenic bacteria
•Streptococcuspneumoniae, Haemophilus influenzae, and Pseudomonas species.
– Skin infections mostly caused by group A streptococci
and Staphylococcus aureus
- An infant will get recurrent bacterial infections around 6 months of age

Question 12

How do you diagnose X linked agammaglobulinemia

Answer 12

Diagnosis:
– Blood tests show complete lack of circulating B cells (determined by B cell marker CD19 and/or CD20),
– As well as low levels of all antibody classes

Question 13

what are tonsils

Answer 13

• lymph nodes

- don’t have any tonsils because he doesn’t have any B cells therefore cannot swell as no response to antigens

Question 14

What are the gene that is affected by X linked agammaglobulinemia

Answer 14

It is problem at BTK gene (a tyrosine kinase) leading to no B-cell maturation
- causes a decline in all antibodies

Question 15

what does BTK stand for

Answer 15

Brutons tyrosine kinase

Question 16

what does BTK do

Answer 16

• It plays a crucial role in B cell maturation
– XLA have normal levels of pre-B cell populations
• Alsoinvolvedinmast cell activation through high-affinity IgE receptor

Question 17

How do you treat X agammaglublinema

Answer 17

Aggressive treatment with
antibiotics for bacterial infections may prevent long-term complications.
• Live viral vaccines (eg, measles, mumps, rubella [MMR]) are contraindicated in these patients
• On the other hand, it has been demonstrated that the dendritic and T-cell responses are normal toward inactivated vaccines

• Replace immunoglobulin
– Intravenous infusion 3-4 weekly for life – Recent FDA approval for Sub cut,
– IM not recommended
• Maintain IgG level at 600mg/dl
• Disaggregated before use – otherwise fevers chills

Question 18

what are the coins fractions=

Answer 18

• Pooled plasma >1000 donors

• Fraction l - fibrinogen
• Fraction ll/lll - immunoglobulins
• Fraction lV
• Fraction V - albumin

Question 19

how are they made

Answer 19

Fractionation involves the addition of ethanol at a low temperature to the plasma
– Cohn fractionation

Question 20

what is otitis media

Answer 20

this is an infection of the middle ear that causes inflammation as a result of a build-up of fluid behind the eardrum,

Question 21

what is erysipelas

Answer 21

this is a bacterial infection in the upper layer of the skin, it is caused by the Group A streptococcus bacterium and results in large raised red patches on the skin, it is usually treated with antibiotics

Question 22

what is pneumonia

Answer 22

this is a swelling of the tissue in one or both of the lungs and is caused by a bacterial infection, the alveoli become inflamed and fill up with fluid

Question 23

what is flow cytometry

Answer 23

it is a technique that is used to measure the volume of cells in a solution as they pass through the instruments laser at rates of 10,000 cells per second, it analyses the physical and chemical characteristics of particles

Question 24

what is CD3

Answer 24

T lymphocyte surface antigen, it has a 3 chain polypeptide, it is important during the assembly of TCR complex, it controls surface expression of the TCR complex and they trigger signal transduction following TCR ligation

Question 25

what is a pan T cell marker

Answer 25

cell markers found on all T cells

Question 26

T cell proliferation indicies

Answer 26

a proliferation index is the average number of divisions that all cells have undergone after they have been stained by a cell proliferation dye, therefore it is the number of times a T cell has undergone proliferation

Question 27

concanavalin A

Answer 27

this is a type of lectin that binds to carbohydrates,

Question 28

tenant toxoid

Answer 28

this is an inactive vaccination used to prevent tetanus, there are 5 does given during childhood and a sixth one is given during adolescence

Question 29

diphtheria toxoid

Answer 29

this is a diphtheria toxin that has been altered so it can no longer harm the person who it is vaccinated into, it stimulates the production of antibodies against diphtheria therefore prevents the person from getting diphtheria

Question 30

IVIG

Answer 30

A blood product which is prepared from between 1000 -15,000 differnet donor blood samples therefore has antibodies from 1000 different people and purify a fraction of the blood which contains IVIG which contains gamma globulins from 1000 different people

Question 31

phytohemagglutinin

Answer 31

this is a lectin that is in a plant, when it is in the diet that effect the digestion in the small intestine, they break down in the digestive tract and change the metabolism of the epithelia cells