What is an 'immunocompromised' host?
State in which the immune system is unable to respond appropriately and effectively to infectious microorganisms.
This is due to a defect in one or more components of the immune system.
Which portion of immunity is it more dangerous to be immunocompromised in?
The adaptive immune response.
What is primary immunodeficiency?
Where the person affected has had immune problems from birth (it is congenital).
This can involve:
- Missing a protein (prevents immune cells from maturing)
- Missing a cell
- Non-functional components
What is secondary immunodeficiency?
Where the patient has acquired an immunocompromising disease.
This can involve:
- Decrease in production of immune components
- Increase in loss of immune components
(commonly happens in malnutrition)
When should you suspect an immunodeficiency?
Infections that suggest an underlying immune deficiency:
Severe: life threatening
Persistant: an infection that persists despite normal treatment
Unusual: an unusual site or microorganism of infection
Recurrent: keeps coming back even after treatment
What are the different kinds of primary immunodeficiency diseases?
- Antibody deficiencies
- Combines T and B cell deficiencies
- Phagocytic defects (mainly neutrophils)
What is the most likely primary immunodeficiency disease if the age of symptom onset is less than 6 months?
A T cell or phagocyte defect.
What is the most likely primary immunodeficiency disease if the age of symptom onset is between the ages 6 months to 5 years?
B cell/antibody or phagocyte defect.
What is the most likely primary immunodeficiency disease if the age of symptom onset is over 5 years old?
B cell, antibody, or complement defect.
Can also consider a secondary immunodeficiency.
What are some of the main primary immunodeficiency diseases?
- Severe Comprimised Immunodeficiency (SCID): T cell defeciency
- Bruton's disease (X-linked): Antibody deficiency
- Chronic Granulomatas Disease (CGD): phagocytic defect
- Combined Variable Immunodeficiency (CVID): Antibody deficiency
What supportive treatment can be used for primary immunodeficiencies?
- Infection prevention
- Treat infections promptly
- Nutritional support (vitamins)
- Avoid live attenuated vaccines
What specific treatment can be used for primary immunodeficiencies?
- Regular immunoglobulin therapy
In SCID: haematopoietic stem cell therapy (90% success rate)
How can an immunodeficiency disease be tested for?
- Tests for humoral (antibody) immunity
- Tests for cell mediated immunity
- Tests for phagocytic cells
Definitive tests also used for molecular testing and gene mutations.