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Immunity, Infection and Haematology > Immune system in health > Flashcards

Immune system in health Flashcards

1
Q

What are the properties of an ideal vaccine?

A 
Safe to the patient
Prevent infection in all cases
Cross reactive
Lifelong protection
Easy to administer
Stable
Not too expensive (global health)
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2
Q

What are the risks of live attenuated vaccines? Examples?

A

Risk of reverting to the wild type pathogenic genotype e.g. live attenuated type 3 Sabin polio vaccine

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3
Q

What are the two types of vaccination?

A

Passive and active

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4
Q

What is an example of passive immunity?

A

Transfer of maternal IgG into the foetal blood during the last trimester - esp important for protection against encapsulated bacteria (requires TI2 antibody responses which do not develop until later in life)

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5
Q

How is protection against specific microbes achieved in passive vaccination?

A

Pooled serum donors with high titres of neutralising antibody are used

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6
Q

What are examples of human serum vaccines?

A

Rabies, Rhesus D, VZV

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7
Q

What is an example of animal serum vaccine?

A

Tetanus

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8
Q

What is the problem with animal serum vaccines?

A

Risk of hypersensitivity reactions against the animal immunoglobulin which is recognised as foreign

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9
Q

What does active vaccination involve?

A

Injecting the infectious organism (or parts of it) into the individual before exposure to the infectious organism

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10
Q

What are examples of whole micro-organism vaccinations?

A

Live attenuated - BCG, Yellow Fever,VZV, MMR

Dead - whole-cell Pertussis, Rabies

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11
Q

What are examples of vaccines with subunit of micro-organism?

A

Inactivated toxin - tetanus, diphtheria toxoid
Recombinant proteins - Hep B, HPV
Polysaccharide - pneumococcus, meningococcus, haemophilus
Conjugate vaccines polysaccharide combined with more immunogenic conjugate to elicit T cell help

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12
Q

What are adjuvants?

A

Materials injected with vaccine antigen to enhance immune response

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13
Q

What is the most widely used adjuvant?

A

Alum - onto which the microbial antigen is adsorbed?

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14
Q

How do adjuvants work?

A

Convert the soluble protein to particulate material, which is more readily phagocytosed by APC. It provides a depot of slow release of antigen

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15
Q

What is an example of co-administration of vaccines?

A

Pertussis with diphtheria & tetanus toxoid

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16
Q

What is an incomplete Freund’s adjuvant?

A

Water in oil emulsion

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17
Q

What is a complete Freund’s adjuvant?

A

Composed of inactivated mycobacteria emulsified in oil

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18
Q

What are conjugate vaccines?

A

Infants can’t produce antibody responses against bacterial capsular polysaccharides - so the polysaccharide is conjugated to protein antigens like Diphtheria and Tetanus toxoids. B cells can internalise the conjugate and present the protein, and obtain help from T cells

19
Q

At what stage of life are lymphocyte numbers highest? What are these lymphocytes like?

A

Just after birth

Naive, do not respond well to antigen

20
Q

What is the most prominent antibody class in neonatal period?

A

IgM

21
Q

What problems are associated with Congenital Rubella?

A

Sensorineural deafness
Eye disease - retinopathy, cataract, microphthalmia
Congenital heart disease

22
Q

What are other congenital transplacental infections?

A

Toxoplasmosis, CMV, Herpes, Syphilis

23
Q

When is transplacental IgG important for the foetus?

A

First 3-6 months of life

24
Q

When do maternal IgG get transported across the placenta?

A

Last trimester of pregnancy

25
Q

What antibodies do not cross the placenta?

A

IgA & IgM

26
Q

What is the problem with placental IgG?

A

Transmission of IgG mediated autoimmune disease
e.g. Neonatal myasthenia gravis (IgG against acetylcholinesterase), Neonatal heart block in RO positive SLE patients (RO antibody destroys nerve conduction fibres in foetus)

27
Q

What is transient hypogammaglobulinaemia of infancy (THI)?

A

When there is a delay in the infant developing IgG, thus total IgG concentrations remain low

28
Q

What are the benefits of vaccination against pertussis for pregnant women?

A

Boost their IgG antibody levels so that these can be transmitted to foetus

29
Q

What does human milk contain that help protect against early infections?

A

Secretory IgA antibodies, bactericidal proteins (e.g. lactoferrin), cytokines

30
Q

What is done to overcome difficulties with infant immmunisation schedules?

A

Use of conjugate rather than polysaccharide vaccines

31
Q

What is immunosenescence?

A

Gradual deterioration of the immune system with age

32
Q

What changes occur in haematopoiesis?

A

Number of haematopoietic cells ↓, and those that remain are biased towards myeloid lineage therefore number of lymphoid cells ↓ (not pathological)

33
Q

What do changes in cytokines cause?

A

Immuno-ageing (increased inflammation)

34
Q

What are the changes with cytlkines?

A

↑ level of circulating PRO-inflammatory cytokines and CRP

↓ level of ANTI-inflammatory cytokine (IL-10)

35
Q

What are the pro-inflammatory cytokines that increase with age?

A

IL-1B, IL-6, TNF

36
Q

What does inflamm-ageing contribute to?

A

Many age-related conditions e.g. CVD, insulin resistance, sarcopenia, dementia

37
Q

What are the causes of inflamm-ageing?

A

↓ sex hormones, production of cytokines by senescent cells, low level of production by macrophages

38
Q

What happens to neutrophils with age?

A

Number not changed
↓ bactericidal processes used by neutrophils
Chemotaxis reduced –> ↑ time taken for neutrophils to reach site of infection
Phagocytosis ↓
Ability to generate reactive oxygen species ↓(cytotoxic effects)

39
Q

What happens to monocytes with age?

A 
↑ circulating monocyte number, but decreased function 
↓ TLR-induced cytokines
↓ phagocytosis
↓ ROS generation
↓ production of IL-6
40
Q

What happens to NK cells with age?

A

↑ number
↓ proliferation in response to IL-2
↓ Cytotoxicity
↓ Telomere length

41
Q

What happens to T lymphocytes with age?

A

↓ T cell producing capacity –> ↓ naive cells
↑ memory T cells
↓ Production of and response to IL-2
↓ telomere length –> ↓ proliferative capacity
↓ co-stimulatory molecule CD28 on surface
Acquire NKG2D (normally receptor of NK cells)
Acquire ability to induce apoptosis in other cells
Lose their helper function

42
Q

What happens to B lymphocytes with age?

A

↑ memory B cells
↓ telomere length
↓ ability to proliferate
↓ ability to produce high affinity antibodies via the germinal centre reaction
↓ diversity of antibodies produced
↑ autoreactive antibodies due to peripheral tolerance

43
Q

What are the main consequences of immunosenescence for health?

A

Increased susceptibility to infections
Decreased response to vaccination
Increased autoimmunity (↑ autoantibodies e.g. rheumatoid factor, anti-ssDNA antibodies)

Immunity, Infection and Haematology (6 decks)

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