14. Immunocompromised Host

Question 1

What is an immunocompromised host?

Answer 1

State in which the immune system is unable to respond appropriately and effectively to infectious microorganisms, due to a defect in one or more components of the immune system.

Question 2

What is the cause of primary immunodeficiency?

Answer 2

Congenital - intrinsic gene defect leading to a missing protein, missing cell or non-functional components of the immune system.

Question 3

What is the cause of secondary immunodeficiency disease?

Answer 3

Acquired - due to an underlying disease or treatment causing either decreased production or function of immune components, or increased loss or catabolism of immune components.

Question 4

What is the mnemonic for infections in a patient that suggest underlying immune deficiency?

Answer 4

S - severe life threatening infection.
P - persistent infection despite normal treatment.
U - unusual site of infection (deep seated infection) or microorganism.
R - recurrent infection.

Question 5

What other than recurrent infections can suggest a primary immunodeficiency disease?

Answer 5

A family history of primary immunodeficiency disease

Question 6

What 3 things can primary immunodeficiency disease patient prevent with as non-infectious manifestations?

Answer 6

Autoimmunity.
Malignancy.
Inflammatory responses.

Question 7

Give 3 examples of primary immunodeficiency diseases that fit into the classification of ‘predominantly antibody deficiencies’.

Answer 7

Common variable immunodeficiency.
Selective IgA deficiency (mostly asymptomatic unless have another condition eg IgG deficiency also).
IgG subclass deficiency.

Question 8

Give an example of a primary immunodeficiency disease that fits into the classification ‘combined T and B cell’.

Answer 8

Severe combined immunodeficiency (SCID).

Question 9

Give an example of a primary immunodeficiency disease that fits into the classification ‘phagocytic defects’.

Answer 9

Chronic granulomatous disease (affects neutrophils and their ability to carry out respiratory burst).

Question 10

If the onset of symptoms is at < 6 months old then what type of primary immunodeficiency does this suggest?

Answer 10

T-cell or phagocyte defect

Question 11

If the onset of symptoms is at > 6 months old and <5 years old then what type of primary immunodeficiency does this suggest?

Answer 11

B-cell/antibody or phagocyte defect

Question 12

If the onset of symptoms is at > 5 years old then what type of primary immunodeficiency does this suggest?

Answer 12

B-cell/antibody/complement or secondary immunodeficiency

Question 13

What type of infections is a patient likely to get with complement deficiency causing primary immunodeficiency disease? How does this manifest in the body?

Answer 13

Neisseria and Strep bacteria.

Pyogenic infections, meningitis/sepsis/arthritis, angioedema.

Question 14

What type of infections is a patient likely to get with phagocytic defects causing primary immunodeficiency disease? How does this manifest in the body?

Answer 14

Staphylococcus aureus bacteria, Candida and aspergillus fungi.
Skin/infections, deep seated infections, invasive fungal infection.

Question 15

What type of infections is a patient likely to get with antibody deficiency causing primary immunodeficiency disease? How does this manifest in the body?

Answer 15

Strep and staph bacteria, enteroviruses.

Sinorespiratory infections, arthropathies, GI infections, malignancies, autoimmunity (eg allergies).

Question 16

What type of infections is a patient likely to get with T cell defects (links to B cell defects) causing primary immunodeficiency disease? How does this manifest in the body?

Answer 16

Strep, staph and salmonella typhi bacteria, all viruses, candida and aspergillus fungi.
Death if not treated, failure to thrive (eg low weight), deep skin and tissue abscesses, opportunistic infections.

Question 17

What do patients with chronic granulatomous disease tend to present with?

Answer 17

Pulmonary aspergillosis and skin infections.

Question 18

Name 3 forms of supportive treatment for management of primary immunodeficiency diseases

Answer 18

Prophylactic antimicrobials.
Treat infections promptly and aggressively.
Nutritional support - vitamins A/D.
Use UV-irradiated CMVned blood products only.
Avoid live attenuated vaccines.
Avoid non essential exposure to radiation.

Question 19

Give 2 specific treatments of primary immunodeficiency disease

Answer 19

Regular immunoglobulin therapy of IgG serum, which is a life long treatment eg for CVID.
SCID - hematopoietic stem cell therapy.

Question 20

Give 3 comorbidities associated with primary immunodeficiency diseases

Answer 20

Autoimmunity.
Malignancies.
Organ damage.

Question 21

Give 5 causes of secondary immunodeficiencies caused by decreased production of immune components

Answer 21

Malnutrition.
HIV infection.
Liver diseases.
Lymphoproliferative diseases (and chemo also).
Splenectomy (eg via autoimmune haemolytic disease).

Question 22

What is the immune function of the spleen?

Answer 22

Immune reaction to bloodborne pathogens including encapsulated bacteria.
Antibody production (IgM and IgG).
Splenic macrophages remove opsonised microbes and immune complexes.

Question 23

How do asplenic/splenectomised patients with secondary immunodeficiency disease present?

Answer 23

Increased susceptibility to encapsulated bacteria eg strep and neisseria. Also with overwhelming post-splenectomy infection eg sepsis and meningitis.

Question 24

How would you manage an asplenic/splenectomised patient with secondary immunodeficiency disease?

Answer 24

Penicillin prophylaxis.
Immunisation against encapsulated bacteria.
Medic alert bracelet and card.

Question 25

Why do patients with haematological malignancy eg lymphomas have increased susceptibility to infections in secondary immunodeficiency disease?

Answer 25

Chemotherapy-induced neutropenia.
Chemotherapy-induced damage to mucosal barriers.
Vascular catheters eg Hickman line.

Question 26

Give 2 causes of secondary immunodeficiencies caused by increased loss or catabolism of immune components

Answer 26

Protein-losing conditions eg nephropathy and enteropathy.

Burns.