Immunodeficiency

Question 1

What are secondary immunodeficiency’s

Answer 1

Components immune system present + function
Acquired diseases or Rx affect immune function
Much more common than primary but present same way - Infection
- Environment
- Disease
- Iatrogenic

Question 2

What are environmental causes

Answer 2

Malnutrition 
- Zinc - monocyte, B and T cells, NK
- Iron - enzymes 
Trauma
Burns

Question 3

What diseases cause secondary immunodeficiency

Answer 3

Infection - HIV
DM
Renal failure
Asplenia 
CLL, lymphoma, myeloma

Question 4

What are iatrogenic causes of SID

Answer 4

Surgery
Splenectomy
Immunosuppression
Anti-rheumatic
Anti-epileptic

Question 5

What are PID

Answer 5

Single gene defects leading to missing or abnormal functioning cells of the immune system

Question 6

How are PID classified

Answer 6

Ab disorder >50%
Predominantly T cell 
Severe combined immune deficiency 
Phagocyte disorder
Complement deficiency 
Absence of polymorphism of PRR 
Autoimmune / auto-inflammatory syndromes
Unclassified

Question 7

What do Ab disorders lead too

Answer 7

Absent B cell so no Ab
Recurrent bacterial infections
Staph, strep, H influenza

Question 8

What do T cell disorders lead too

Answer 8

Unusual or opportunistic infection - usually viral
PJP / CMV / herpes / toxoplasmosis 
Candida / aspergillus 
Mycobacteria / listeria 
FTT

Question 9

When do you suspect PID

Answer 9

Severe infection requiring hospital or IV Ax
Persistent infection that doesn't clear 
- 4+ new ear in children or 2+ adult
- 2+ serious sinus in 1 year
- 2+ pneumonia 
- 2+ deep skin or organ abscess 
- Thrush or fungal 
Unusual infections - aspergillus / CMV
RECURRENT
Chronic diarrhoea / weight loss / FTT 
FH PID

Question 10

What can you sometimes present with

Answer 10

Malignancy
Syndromes
FTT
Enlarged liver or spleen
Vaccination problems

Question 11

What can phagocyte defect cause

Answer 11

Neutrophil defect
Leucocyte adhesion deficiency
Deficiency of PRR
Chronic granulomatous disease

Question 12

What does neutrophil defect cause

Answer 12

Congenital neutropenia

Very severe immune defect

Question 13

What does leucocyte adhesion defect cause

Answer 13

Unable to phagocytose as no CD11/CD18 for neutrophils to attach
Present like congenital neutropenia but not as severe
Normal blood WCC but can’t mount a response

Question 14

What does deficiency of PRR lead too

Answer 14

Can’t recognise foreign antigen so can’t phagocytose

Neutrophils migrate but don’t recognise

Question 15

How is chronic granulomatous disease inherited and what does it lead too

Answer 15

X-linked / XR

Neutrophils cannot kill as no NAPDH oxidase

Question 16

What does it cause

Answer 16

Aspiergillus pneumonia

S.aureus abscess in lungs / liver

Question 17

What are clinical presentation of phagocyte defects

Answer 17

Pneumonia
OM
Skin / mucous membrane infection
Liver abscess

Question 18

What organisms are involved

Answer 18

S.aureus
E.coli
Salmonella
Aspergillus / candida

Question 19

What infections do complement defects lead too

Answer 19

S.aureus
Strep pneumonia
Meningococcal
Often fatal meningitis 
No chemotaxis / opsonisation / lysis of organisms

Question 20

What is hereditary angioedema

Answer 20

AD CI inhibitor deficiency so can’t block bradykinin

Question 21

What does it lead too

Answer 21

Recurrent painless, non-pitting, non-pruritic, non erythematous swelling
Affects subcutaneous tissues, intestines and oropharynx

Question 22

What is emergency

Answer 22

Pharyngeal obstruction

Acute abdomen pain

Question 23

How do you Dx and treat

Answer 23

Measure C4 level of complement - will be low
CI inhibitor infusion
Anabolic steroid as prophylaxis
FFP not available

Question 24

What are most common disorders of adaptive immunity

Answer 24

B cell over T cell

Question 25

What B cell issues can you get

Answer 25

Absence mature B cells due to stop in bone marrow Defective function Absence of Ig production Absence of specific class of Ig Absence of functional Ab - there but don't function

Question 26

What is SCID and what causes

Answer 26

Severe dysfunction in T and B cells | Caused by defect in pluripotent stem cell, lymphoid stem cells or T or B cell

Question 27

How does it present

Answer 27

``` Well for first few months as maternal Ab Persistent candida Persistent diarrhoea FTT Unwell after live vaccines Oppurtunistic infections very severe - chicken pox, PJP, CMV Chronic bronchiolitis Interstitial pneumonitis Bacterial sepsis ```

Question 28

How do you Rx

Answer 28

Nutritional support Prophylactic Ax, anti-fungal + anti-viral Ig replacement therapy Bone marrow donor = cure

Question 29

What is DiGeorge

Answer 29

22q11 deletion syndrome | Causes T cell deficiency

Question 30

How does it present

Answer 30

``` Congenital cardiac Palate defect Characteristic facial Immunoeficiency due to thymus hypoplasia Developmental delay / LD Hypocalcaemia Psychaitric Haematological + ALL ```

Question 31

What is mneumonic

Answer 31

``` CATCH 22 Cardiac abnormality Abnormal face Thymus hypoplasia / T cell Cleft palate Hypocalcaemia due to hypoPTH ```

Question 32

What are immune disorders associated

Answer 32

``` Recurrent RTI Autoimmune as no T cell Anaemia Thrombocytopenia JIA Raynaud's Thyroid ```

Question 33

How do you Rx

Answer 33

Thymus transplant

Question 34

What causes invasive fungal

Answer 34

``` Problem with innate or adaptive immune system Presenting Sx of PID Neutropenia due to leukaemia or chemo Immature immune in neonate Broad spec Ax / abode surgery ```

Question 35

What are main pathogens

Answer 35

Cryptococcus Candida Aspergillus Pneumocystitis

Question 36

What are RF for neonatal fungal

Answer 36

``` Premature LBW PID Catheter RF neutropenia Parenteral nutrition Steroids H2 blocker Abdo surgery Broad spec Ax Hypoglycaemia ```

Question 37

When is cryptococcal common and what does it cause

Answer 37

CD4 deficiency - HIV / severe immunosuppressed | Cause meningitis

Question 38

When is pneumocystis common and what does it cause

Answer 38

CD4 deficiency | Pneumonia

Question 39

When is Aspergillus common and what does it cause

Answer 39

Innate neutrophil disorder | Pneumonia / invasive / asprgilloma

Question 40

When is Candida common and what does it cause

Answer 40

Systemic = phagocytic Mucosal = T cell Blood stream / urinary / skin

Question 41

How do you investigate PID

Answer 41

FBC - reduced WCC suggest T, reduced neutrophils suggest phagocyte Serum IgG or IgA - B cell disorder Measure complement activation Immunophenotype HIV test if relevant Sweat test for CF CXR / CT for bronchiectasis / scarring from infections

Question 42

How do you manage PID

Answer 42

``` Ig if B cell deficient Gene therapy - SCID Stem cell transplant - CGD / SCID Thymus transplant - DiGeorge Genetic counselling ```

Question 43

What should you avoid

Answer 43

Live vaccine | Blood transfusion