Immunity Flashcards
(159 cards)
What are the 4 types of blood groups and what are their associated antigens and antibodies?
What are the different rhesus antigens?
C, c, D, E, e.
What are the symptoms of haemolytic disease of the newborn?
State why they occur.
Enlarged liver or spleen due to extramedullary haematopoiesis.
Generalised oedema due to heart failure from severe anaemia.
Yellowing of the skin and sclera due to excess bilirubin accumulation.
What lab tests are performed during pregnancy to confirm destruction of red blood cells?
Testing the amniotic fluid or blood from the umbilical cord for bilirubin (unconjugated).
How can haemolytic disease of the newborn be predicted?
Testing the mother for her rhesus antigens - negative is more likely.
Testing the baby for their rhesus antigens - positive is more likely.
Testing the mother for autoantibodies against rhesus D antigens.
Testing for anaemia or bilirubin from the umbilical vein.
How does RhoGam work?
Binds to fetal blood rhesus D antigens, preventing the identification of the positive antigen, preventing production of anti-rhesus-D antibodies.
When should RhoGam be administered?
From week 8 if anti-rhesus D antibodies have been formed before.
From week 28 if the mother’s status wasn’t known prior to this pregnancy.
What is the direct and indirect Coombs test?
Direct - tests the baby’s blood for rhesus-D antibodies, bound to the RBCs after birth.
Indirect - tests the mother’s blood for rhesus-D antibodies.
What are some serological tests that can help confirm diagnosis of myasthenia gravis?
Anti-AChR antibodies.
Anti-striated muscle antibodies.
Anti-tyrosine antibodies.
Anti-thyroid antibodies.
Why can babies transiently present with myaesthenia gravis?
The anti-AChR antibodies are IgG and so can cross the placenta, but are eventually degraded within the body so no longer block the AChRs.
Other than myaesthenia gravis, what are some type V hypersensitivity reactions?
Also, state what subset of hypersensitivity type V is of.
Grave’s disease - stimulates TSH receptors.
Pernicious anaemia - protein blockade, against intrinsic factor in gastric parietal cells.
Type II hypersensitivity reactions.
What is an antigen?
Any substance that triggers an immune response as form of effector T/B cells and antibodies.
What are some cell bound antigens seen in type II hypersensitivity reactions?
Exogenous - blood group antigens, rhesus D antigens.
Endogenous - self-antigens (autoimmune).
What are the potential complications of haemolytic disease of the newborn?
Hydrops fetalis.
Hepatomegaly/ splenomegaly.
Severe hyperbilirubinaemia.
Kernicterus - brain damage due to unconjugated bilirubin crossing the BBB.
What is the Fc receptor, and how can we target this?
A receptor on immune cells and components that can be blocked by immunoglobulins to prevent activation.
What is the pathogenesis of type IV hypersensitivity reactions?
Sensitisation - antigen presenting cells present the antigen to t-helper1 cells, activating them.
Effector - TH1 then produces cytokines such as IFN-gamma, TNF-beta, interleukin-1 and -2.
The cytokines then activate the macrophages, causing superoxide radicals and nitric oxide to be produced, destroying tissues.
What are some steroid sparing agents used in treatment of type III and type IV hypersensitivity reactions?
Anti-proliferative - azathioprine, mycophenolate meofetil.
Cytotoxic - cyclophosphamide.
Anti-metabolite - methotrexate.
Anti-T-cell - cyclosporin.
What are the functions of TH2 cells, and what are they activated by?
B-cells - IgE and IgG production.
Eosinophils - killing pathogens.
Mast cells - allergies.
IL-4.
What are the different types of allergens?
State some examples.
Seasonal exposures - tree/ grass pollens.
Perennial exposure (all the time) - house mite dust, animal dander and fungal spores.
Accidental exposure - insect venom, medicines such as penicillin, latex, foods (milk, nuts and shellfish).
What is the hygiene hypothesis?
Children exposed animals, pets and microbes in the early postnatal period have greater protection against certain allergic diseases.
What is the biodiversity hypothesis?
Western lifestyle induces alteration of the symbiotic relationships with parasites and bacteria, leading to dysbiosis (compositional and functional alterations of the microbiome).
What can the impact of dysbiosis be?
Increased auto-immune diseases - crohns, UC, allergies, etc.
Obesity.
Type II diabetes.
Colorectal cancer.
Autism.
What is the sensitisation of allergies?
What is the effector phase of allergens?