PBL3 Flashcards
what does IgA do
Mucosal areas, such as gut, respiratory tract and urogenital tract. Prevents colonization by pathogens. Also in saliva, tears, and breast milk.
what does IgD do
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.
What does IgE do
Binds to allergens and triggers histamine release from mast cells and basophils, and is involved
in allergy. Protects against parasitic worms.
what does IgG do
Provides the majority of antibody-based immunity against invading pathogens. Only antibody capable of crossing the placenta to give passive immunity to the fetus.
What does IgM do
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.
what do antibodies do
- agglutination
- neutralisation
- complement
- antibody dependent killing cells
- opsinization
what is IgG able to do
– Provides passive immunity for up to 1st 6 months of life
– IgG long half life in serum (~month) sequestered in liver and endothelial cells
What does IgA do
IgA is in breast milk
– Ambrose breast fed provides some immunity
what causes the long half life of IgG
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
describe X linked agammaglobulinemia
• X-linked recessive
– Approx 1:100,000 -1:300,000 • Extremely rare in females
• Life expectancy 40+ years
What are the symptoms of X linked agammaglobulinemia
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
How do you diagnose X linked agammaglobulinemia
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
what are tonsils
- lymph nodes
- don’t have any tonsils because he doesn’t have any B cells therefore cannot swell as no response to antigens
What are the gene that is affected by X linked agammaglobulinemia
It is problem at BTK gene (a tyrosine kinase) leading to no B-cell maturation
- causes a decline in all antibodies
what does BTK stand for
Brutons tyrosine kinase
what does BTK do
• 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
How do you treat X agammaglublinema
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
what are the coins fractions=
• Pooled plasma >1000 donors
- Fraction l - fibrinogen
- Fraction ll/lll - immunoglobulins
- Fraction lV
- Fraction V - albumin
how are they made
Fractionation involves the addition of ethanol at a low temperature to the plasma
– Cohn fractionation
what is otitis media
this is an infection of the middle ear that causes inflammation as a result of a build-up of fluid behind the eardrum,
what is erysipelas
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
what is pneumonia
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
what is flow cytometry
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
what is CD3
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
