Infection Week 10 - Immunodeficiency Flashcards
Why do patients get permanent tissue damage when immunodeficient?
As it takes a while to diagnose and get symptoms, so often quite late when diagnosed
What is an Immunocompromised host?
A host which has an immune system which is unable to respond appropriately and effectively enough to infectious microorganisms.
A host which has a defect in one or more components of the immune system
What are the Immunocompromised patients at risk of?
Infections from opportunistic pathogens
Infections from normal/otherwise harmless pathogens
How do we recognise that a patient may be immunodeficient?
If the infections are Severe Persistant Unusual Recurrent
What are the 2 Classifications of immunodeficiency?
Give a quick definition of each
Primary- intrinsic and usually inherited defect
Secondary- decreased production of immune components due to … Malnutrition, infection, liver disease, splenectomy etc
Why are primary immune deficiencies more often in males?
As they are X linked
What are the four primary immune deficiencies?
B cell
T cell
Complement
Phagocyte
Describe the types of B cell deficiencies?
Unable to mature into plasma cells Unable to become IgA Impaired development (due to Brutons disease)
What are patients with B cells more at risk of?
Organisms and Diseases
Makes them more succeptable to bacteria and fungi so…
More respiratory infections (bronchiectasis)
Succeptable to Giardia (GI)
Increase in auto immune disease
Increase in gastric carcinoma and lymphoma
How do you treat B cell deficiencies
Immunoglobulin replacement therapies
Prophylaxis
Avoid radiation
Manage respiratory function
What are the types of phagocyte deficiency?
Defect in CD18 so doesn’t adhere
Can fail to form phagolysosome
Can lack respiratory burst
Cyclic neutropenia
What do patients get with a phagocyte deficiency?
Prolonged and recurrent infections
Get ulcers on membranes
Abcesses
Invasive aspergillosis
How do you treat a phagocyte deficiency?
Prophylactic antibiotics and fun gals
Surgery
Stem cells
Interferon G
What are the types/causes of T cell deficiencies?
Can lack a thymus
Stem cell defects
Thymocytes die
Defective development
What species are T cell deficient patients susceptible to?
Viruses and Fungi
What does a deficiency in C1.2.4 lead to?
Immune complex diseases
What does a deficiency in C3 lead to?
Recurrent bacterial infections
What does a deficiency in C5-9 lead to?
Recurrent neisserial infections
What patients get secondary immunodeficiencies?
Asplenic
Haematological malignancies
Protein losing conditions and burns (as they lose immune components in fluid etc)
Why do asplenic patients become immunodeficient?
The spleen usually makes macrophages and produces antibodies (acute IgM and long term IgG) as well as acting as a filter for blood
Becoming asplenic increases succeptability to encapsulated bacteria (lack opsonins)
What are the bacteria that asplenic patients are more succeptable to?
Examples…
Encapsulated bacteria
Neisseria meningitidis, Strep. Pneumoniae, H influenzae
What is OPSI?
Overwhelming post splenectomy infection
How do you treat/prevent OPSI?
Life long penicillin prophylaxis
Immunisation
What are the types of haematological malignancy immune deficiencies?
Both increase infection risk
Chemotherapy induced
Due to vascular catheter or Hickman lines
How do we test Humeral immunity?
Measure antibodies in response to test immunisation
Testing for IgG, IgA, IgM
How do we test cell mediated immunity?
FBC for lymphocytes
In vitro test for T cell function
Lymphocyte subset analysis
How do we test phagocytic cells
Neutrophil function test
Adhesion molecule expression
What other test do we do for immunodeficiency?
Test for complement proteins
Definitive tests
What is immunodeficiency associated with?
Autoimmune disease
Malignancy
