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Flashcards in Immunology Deck (48):
1

what are features suggestive of immunodeficiency

SPUR

Serious infections
Persistent infections
Unusual infections
Recurrent infections

2

what are other features suggestive of a primary immune deficiency

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

3

what are conditions associated with secondary immune deficiency

extremes of life - ageing, premature
HIV
Measles
Immunosuppressive Tx
Anti-cancer Tx
Cancer of immune system - lymphoma, leukaemia, myeloma
Mets
Malnutrition
DM

4

what is the commonest form of severe combined immunodeficiency

X-linked SCID

5

what causes SCID

mutation of IL2 receptor

6

what does the mutation in SCID results in

In inability to respond to cytokines
- failure of T cell and NK cell development
- production of immature B cells

7

what is the number of T/B cells seen in X-linked SCID

Very low or absent T cells

Normal or increased B cells

8

presentation of severe combined immunodeficiency

Unwell by 3 months of age
Persistent diarrhoea
Failure to thrive
Infections of all types
Unusual skin disease
FX of early infant death

9

what is the IL12-gIFN network pathway

1. macrophage infection with bacteria
2. produces IL12
3. IL12 induces T cells to secrete gIFN
4. gIFN feeds back to macrophages and neutrophils
5. stimulates production of TNF
6. activates NADPH oxidase

10

what happens is there is no TNF

no functional granuloma

11

what is a granuloma

organised collection of activated macrophages and lymphocytes

12

what causes a granuloma to be formed

1. inflammatory response triggered
2. activation of T lymphocytes and macrophages
3. failure of removal of stimulus
4. persistent production of activated cytokines
5. granuloma formed

13

what are examples of conditions where granulomas are formed

Sarcoidosis
TB
Leprosy
Silicosis
Foreign bodies

14

what are antibody mediated autoimmune diseases

Idiopathic thrombocytopaenia
Autoimmune haemolytic anaemia

15

what are common variable immune deficiencies

Low IgG, IgA and IgM

Recurrent bacterial infections, esp. respiratory

Often associated with autoimmune disease

16

what is a relatively common antibody deficiency

Selective IgA deficiency

17

what are Sx of selective IgA deficiency

1/3rd have recurrent resp tract infections

2/3rd are asymptomatic

18

Ddx of recurrent bacterial infections AND hypogammaglobulinaemia

Antibody deficiency

Protein loss i.e. nephrotic syndrome

Failure of protein syntheses e.g. myeloma, lymphoma, CLL

19

what are the classifications of hypersensitivity reactions

Type I: Immediate hypersensitivity (IgE-mediated allergy)
Type II: Direct cell killing: antibody mediated
Type III: Immune complex mediated (example: SLE)
Type IV: Delayed type hypersensitivity

20

what organ secretes complement proteins

the liver

21

what is lysis

direct killing of bugs by punching holes in it

22

what is the function of natural killer [NK] cells

kill cells that lack MHC – molecules on surface

23

what is meant by the term 'natural' in NK cells

no need for antigen specificity

24

why couldn't we just have NK cells

they have no long term memory

25

what immune system are NK cells part of

innate immunity

26

what receptors are seen on the cells that are part of the innate immunity

toll-like receptors [TLR]

27

why are TLR important

expressed on phagocytes and dendrites as built-in burgler alarm for microbes

activation causes pro-inflammatory cytokines and type 1 Interferon secretion

28

what can TLR dysfunction cause

immunodeficiency (too little) or autoimmunity (too much)

29

what treatment activates TLR to boost immunity and through which number receptor

imiquimod,

activating TLR7/8

30

what blocks pro-inflammatory cytokines

TNF inhibitors

31

what is the job of TNF-alpha

secreted as an immediate-early ‘fire alarm’ signal in response to many stressors

32

what are the 4 types of transplant rejection

hyperacute rejection
acute cellular rejection
acute vascular rejection
chronic allograft failure

33

hyperacute rejection = time, pathology, mechanism, Tx

T - mins to hours

P - thombosis & necrosis, Type II hypersensitivity

M - preformed antibody and complement fixation

Tx - none

34

acute cellular rejection = time, pathology, mechanism, Tx

T - 5 to 30 days

P - cellular infiltration, Type IV hypersensitivity

M - CD4 and CD8 T cells

Tx - immunosuppresion

35

acute vascular rejection = time, pathology, mechanism, Tx

T - 5 to 30 days

P - vasculitis, Type II hypersensitivity

M - De novo antibody and complement fixation

Tx - immunosuppresion

36

chronic allograft failure = time, pathology, mechanism, Tx

T - > 30 days

P - fibrosis, scarring

M - Immune and non-immune mechanisms

Tx - minimise drug toxicity, hypertension, hyperlipidaemia

37

how do vaccinations work

produce memory in B cells and T cells

38

how does vaccinations work on T cells

simulates rare naive T cells

induces a strong T-cell response in 14–21 days

some become effector T cells which =
- mostly die by apoptosis in absence of antigen
- Smaller no. become memory T cells maintained at low frequency

39

what antibody quickly rises first in primary infection

IgM
- gone by 14 dyas

40

what antibody rises steadily and decreases slowly in primary infection

IgG
- takes years to decrease

41

what antibody is there more of in secondary infection

IgG

however, get the same rapid rise and fall in IgM

42

what are key features of inactivated vaccines

Cannot replicate

Generally not as effective as live vaccines

Immune response primarily antibody based (not T cells)

Antibody titer may diminish with time

Require multiple doses to stimulate immune response

43

advantages of inactivated vaccines

Can be made quickly (prevent epidemics)

Elicit good antibody responses

Easy to store; No refrigeration required

Usually safe

44

disadvantages of inactivated vaccines

Doesn’t stimulate clonal expansion of B and T cells

Require multiple and booster injections

Require adjuvants to improve immunogenicity

45

what are examples of inactivated vaccines

whole cell vaccines
- polio, hep A, cholera, rabies

fractional vaccines
- influenza, hep B, diptheria, tetanus

46

adv of live attenuated vaccine

All relevant effector mechanisms elicited (antibody, activated T cells)

Localised, strong response

Usually only one single dose required

47

disadv of live attenuated vaccines

safety - may cause infection in immunocompromised

fragile - must be stored carefully

48

examples of live attenuated vaccine

measles
mumps
rubella
yellow fever
MMR jab
BCG