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Flashcards in Immunology Deck (67):
1

Hallmarks of immunodeficiency

Serious infections
Persistent infections
Unusual infections
Recurrent infections

2

Features suggestive of primary immune deficiency

Weight loss or failure to thrive
Severe skin rash (eczema)
Chronic diarrhoea
Mouth ulceration
Unusual autoimmune disease
Family history

3

Primary immunodeficiency

Rare
Hereditary

4

Secondary

Common
Acquired
Often subtle
Often involves more than one component of immune system

5

Conditions associated with secondary immune deficiency

Ageing, Prematurity
Infection
Treatment interventions
Malignancy
Biochemical and nutritional disorders

6

Phagocyte Deficiencies

Defects of phagocyte production, mobilisation and recruitment
Leukocyte Adhesion Deficiency
Defects of recognition
Failure of oxidative killing mechanisms

7

Failure of stem cells to differentiate into neutrophils

Primary defect: Recticular Dysgenesis
Secondary defect: After stem cell transplantation

8

Failure of neutrophil maturation

Kostmann syndrome
Cyclic neutropaenia

9

Recticular dysgenesis

Complete block in leukocyte development
Severe Combined Immuno Deficiency

10

Kostmann Syndrome

Defect in receptor or cytokine GCSF
Blocks neutrophil development
Autosomal recessive disorder
Severe chronic neutropaenia

11

Supportive treatments for kostmann syndrome

Prophylactic antifungals
Prophylactic antibiotics

12

Definite treatments for kostmann syndrome

Stem Cell transplantation
Granulocyte Colony Stimulating Factor

13

Leukocyte adhesion deficiency

Rare primary immunodeficiency
Caused by genetic defect in leukocyte integrins (CD18)
Failure to recognise activation markers expressed on endothelial cells

14

Markers of leukocyte adhesion deficiency

Localised deep tissue bacterial infections that are difficult to detect
Very high neutrophil count

15

Failure of oxidative killing mechanisms

Absent respiratory burst
Deficiency of the intracellular killing mechanism of phagocytes
Inability to generate oxygen free radicals
Failure to degrade chemoattractants and antigens
Persistent accumulation of neutrophils, activated macrophages and lymphocytes

16

Features of chronic granulomatous disease

Recurrent deep bacterial infections
Recurrent fungal infections
Failure to thrive
Lymphadenopathy and hepatosplenomegaly
Granuloma formation

17

Laboratory investigation of chronic granulomatous disease

NBT Test

18

Treatment of chronic granulomatous disease

Prophylactic antibiotics
Prophylactic antifungals
Stem cell transplantation
Gene therapy

19

Investigations in phagocyte recruitment function

Full blood count & differential
Presence of pus
Expression of neutrophil adhesion molecules

20

Investigations in phagocyte recognition function

Chemotactic assays
Phagocytosis assays

21

Investigations in phagocyte killing function

NBT test of oxidative killing

22

What drives immunoglobulin class switching?

CD4 cell

23

What is the first antibody secreted from the bone marrow?

IgM

24

Antibody functions

Antigen receptors (IgM and IgD)
Opsonisation (IgG)
Neutralisation (IgA)
Mast cell activation (IgE)

25

How can the adaptive immune system go wrong?

Defects of hematopoietic stem cells
Defects of lymphoid precursors (SCID)
Failure of Thymic development
Disorders of T cell effector function

26

Clinical phenotype of severe combined immunodeficiency

Unwell by 3 months of age
Persistent diarrhoea
Failure to thrive
Infection of all types
Unusual skin disease
Family history of early infant death

27

Causes of SCID

Deficiency of cytokine receptors
Deficiency of signalling molecules
Metabolic defects
Defective receptor arrangements

28

X-linked SCID

Mutation of a component of the IL-2 Receptor
Results in inability to respond to cytokines
-Failure of T cell and NK cell development
-Production of immature B cells

29

DiGeorge Syndrome

Failure of thymic development
Results in T cell immunodeficiency

30

Phenotype of DiGeorge Syndrome

Congenital heart defects
Cleft palate
Hypocalcaemia
Developmental delay
Psychiatric disorders
Oesophageal atresia
T cell lymphopaenia

31

Laboratory results for DiGeorge Syndrome

Absent or decreased number of T cells
Normal or increased B cells
Normal NK cells numbers

32

Disorders of T cell effector function

Cytokine production
Cytotoxicity
T-B cell communication
(IFNy deficiency, IL-12 deficiency)

33

First line investigations of T cell deficiencies

Total white cell count and differential
Quantitation of lymphocyte subpopulations
Serum immunoglobulins

34

Second line investigations of T cell deficiencies

Functional tests of T cell activation and proliferation
Additional tests of T lymphocyte lineage
HIV test

35

Immune deficiencies affecting B lymphocytes

B cell maturation defects
Failure of TFH cell co-stimulation
Failure of IgA production (Selective IgA deficiency)
Failure of production of IgG (Common variable immune deficiency, Selective antibody deficiency)

36

First line investigations of B cell deficiencies

Total white cell count and differential
Serum/ urine immunoglobulins

37

Second line investigations of B cell deficiencies

Quantitation of B and T lymphocytes
Specific antibody responses to known pathogens

38

Hypersensitivity Reaction

Immune response that results in bystander damage to the self
Usually exaggeration of normal immune mechanisms

39

Type 1 Hypersensitivity reaction

Immediate hypersensitivity

40

Type 2 hypersensitivity reaction

Direct cell killing

41

Type 3 hypersensitivity reaction

Immune complex mediated

42

Type 4 hypersensitivity reaction

Delayed type hypersensitivity

43

What type of hypersensitivity reaction is allergic reaction?

Type 1: Immediate hypersensitivity

44

Allergy

IgE-mediated antibody response to external antigen

45

The 'Hygiene Hypothesis'

Changes in microbial stimuli influences the maturation of the immune response
General decrease in infectious burden during early life
results in increased predisposition to allergic conditions during childhood

46

Vasoactive substances produced by mast cells

Histamine, Tryptase, Heparin
Leukotrienes, prostaglandins
TNFa, IL-4

47

The role of mast cells in allergic reactions

Express receptors for Fc region of IgE antibody on their surface
Release of vasoactive mediators (histamine, tryptase)
Increased cytokine and leukotriene transcription

48

Mast cell stabilisers

Sodium cromoglycate
Stabilises mast cell membranes
Prevents release of inflammatory mediators

49

Anti-histamine

H1 Receptor antagonists
Block biological effects of histamines

50

Leukotriene receptor antagonists

Montelukast
Blocks effects of leukotrienes

51

Adrenaline

Acts on B2 adrenergic receptors to constrict arterial smooth muscle

52

Pathophysiology of direct cell killing (type 2)

Antibody binds to cell surface antigen
Results in activation of complement and opsonisation

53

Functions of antibody

Activates B lymphocytes
Acts as opsonins
Mast cell degranulation
Causes antigen clumping and inactivation of bacterial toxins
Activates antibody dependent cellular activity
Activates complement

54

Effects of complement activation

Chemotaxis
Solubilization of immune complexes
MAC-direct killing of bacteria
Opsonisation

55

Which fragments of complement proteins released after activation increase permeability of blood vessels

Anaphylotoxins (C3a and C5a)

56

Clinical examples of type 2 hypersensitivity

Acute haemolytic transfusion reaction
Drug induced haemolysis

57

Blood type A

Surface antigen A
Anti-B antibodies

58

Blood type B

Surface antigen B
Anti-A antibodies

59

Blood type AB

Surface antigen A and B
Neither anti-A or anti-B antibodies

60

Type O

Neither surface A or B antigens
Anti- A and anti-B antibodies

61

Type 2 hypersensitivity management

Plasmapheresis
Immunosuppression

62

Pathophysiology of type 3 hypersensitivity

Antibodies bind to soluble antigens forming small immune complexes
These are trapped in small blood vessels, joints and glomeruli

63

Management of type 3 hypersensitivity reaction

(Avoidance)
Corticosteroids to reduce inflammation
Immunosuppression to decrease production of antibody

64

Autoimmune diseases associated with delayed hypersensitivity reaction

Type 1 diabetes
Psoriasis
Rheumatoid arthritis

65

Non-autoimmune diseases associated with delayed hypersensitivity reaction

Contact dermatitis
Tuberculosis
Leprosy
Sarcoidosis
Cellular rejection of organ transplant

66

Pathophysiology of type 4 hypersensitivity reaction

Initial sensitisation to antigen creates 'primed' generation of effector Th1 and memory T cells
Subsequent exposure activates previously primed T cells
Recruitment of macrophages, lymphocytes, neutrophils, proteolytic enzymes, inflammation...

67

Management of type 4 hypersensitivity reaction

Watchful waiting
NSAIDS
Systemic corticosteroids