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 MO

Question 2

In general what is the cause of immunodef?

Answer 2

Defect in one or more components of the immune system: innate or adaptive

Question 3

A def in which cell would cause a more severe immune system def?

Answer 3

B cell

Question 4

What is primary vs sec immunodef?

Answer 4

P = congenital: intrinsic gene defect
S = acquired: underlying disease/treatment

Question 5

When should you suspect immunodef?

Answer 5

S = severe
P = persistent
U = unusual
R = recurrent

Question 6

What is an opportunistic infection?

Answer 6

• infectionthat takes advantage of an opportunity not normally available, such as a host with a weakened immune system, an altered microbiota (such as a disrupted gut flora), or breached integumentary barriers.
• Example = herpes virus

Question 7

What is SCID?

Answer 7

• Severe combined immunodef

- T cell and B cell def

Question 8

What does immunodef increase the risk of?

Answer 8

Infection, Cancer/malignancies

Question 9

What is CVID?

Answer 9

• Common viable immunodef

- High risk of cancer

Question 10

What is selective IgA def?

Answer 10

Quite prevalent but most asymptomatic

Question 11

In regards to immunodef, outline phagocytic defects?

Answer 11

• Chronic granulomatous disease CGD = count fine, function defective (skin infect, pulmonary aspergillosis)
• Severe congenital neutropenia

Question 12

How does the age on onset link to the type of primary immunodef?

Answer 12

• <6 months = T cell or phagocyte defect
• > 6 months – 5 years = B cell/Ab or phagocyte defect
• > 5 years = B cell/Ab/complement or secondary immunodef

Question 13

What infection are complement def associated with?

Answer 13

Bacterial

Question 14

What infections are phagocytic defect associated with?

Answer 14

Bacterial and fungal

Question 15

What infections are Ab def associated with?

Answer 15

Bacterial, viral, protozoa

Question 16

What infections are T cell defect associated with?

Answer 16

Bacterial, viral, fungal, protozoa

Question 17

How does different defs in complement link with infection type?

Answer 17

• C3 = pyogenic
• C5-C9 = meningitis/sepsis/arthritis
• C1 = angiooedema

Question 18

Outline how immunodef can be managed

Answer 18

• Supportive = infect prevention,immunisation, vits, blood products, avoid live attenuated vacs
• Specific = Ig therapy, SCID – hematopoietic stem cell therapy
• Manage comorbidities = lung function assessment

Question 19

What is Ig replacement therapy?

Answer 19

• Donor Ig
• Goal IgG >8g/l
• Life long treatment

Question 20

What is the main cause of immunodef worldwide?

Answer 20

Malnutrition

Question 21

What causes secondary immune def?

Answer 21

Decreased prod of immune components = Malnutrition, infection, liver disease, lymphoproliferative diseases, splenectomy, loss/catabolism of immune components

Question 22

Why is the spleen so important?

Answer 22

• Encapsulated bacteria
• Ab prod
• Splenic macrophages

Question 23

What types of treatment increase the susceptibility to infections?

Answer 23

• Chemo-induced neutropenia
• Chemo-induced damage to mucosal barriers
• Vascular catheters

Question 24

In what situations and illnesses is a patient immunocompromised?

Answer 24

• Chemo
• HIV
• Broken barriers

Question 25

What are the lab investigations for immunodef?

Answer 25

• General = FBC, differential
• Humoral = Igs, levels specific to vaccines, test immunisation
• Cell mediated = lymphocyte count/subsets, T cell function
• Phagocytic cells = neutrophil count
• Complement