Immunology - Complement Disorders Flashcards
What are complement disorders?
Disorders affecting complement proteins that make up the complement system which help destroy pathogenic cells
What type of organisms are complement proteins crucial for dealing with?
Encapsulated organisms
What are some examples of encapsulated organisms?
Haemophilus influenza B
Streptococcus pneumonia
Neisseria meningitidis
What do complement deficiencies cause in children?
Increased susceptibility to
- Respiratory tract infections
- Ear infections
- Throat infections
What are complement deficiencies also associated with?
Immune complex disorders e.g. SLE
Why are complement deficiencies associated with immune complex disorders?
Immune complexes build up and are deposited in tissues
This causes chronic inflammation
C2 deficiency is the most common
What is extremely important for all children with complement disorders?
Vaccination against encapsulated organisms
What is C1 Esterase Inhibitor Deficiency?
AKA Hereditary Angioedema
C1 esterase inhibits bradykinin, reduced C1 esterase leads to reduced inhibition of bradykinin
This causes increased blood vessel dilatation and increased vascular permeability
This causes intermittent angioedema
What can trigger intermittent angioedema?
Minor triggers e.g. viral infections, stress or no clear reason
Where does angioedema affect?
Lips or face
Can occur anywhere on the body including respiratory and GI tract
Can also occur in larynx and compromise the airway
How can patients with hereditary angioedema be treated?
IV C-1 esterase inhibitor
Prophylaxis before dental or surgical procedures
Or in response to acute attacks of angioedema
What is the key test for diagnosing hereditary angioedema?
Check C4 levels
C4 levels are low in C1 esterase inhibitor deficiency
What is mannose-binding lectin deficiency?
Relatively common
Deficiency leads to inhibition of the alternative pathway of the complement system
No major issues in most patients
In patients who are particularly susceptible to infection e.g. CF, can lead to more severe variant of their disease
