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Flashcards in Immunology Deck (85):
1

What do mycobacteria infect?

They infect antigen presenting cells

2

Where are the blood tissue barriers and hence immune privileged tissues?

Blood-brain barrier
Blood-ocular barrier
Blood-testis barrier

3

What are warm antibodies?

IgG

4

What are cold antibodies?

IgM

5

Which antibodies form monomers?

IgG
IgE
IgD

6

Which antibodies form dimers?

IgA

7

Which antibodies form pentamers?

IgM

8

Which antibodies cannot cross the placenta?

IgM

9

Give examples of uses of passive immunity

Anti-venins
Pooled Ig for immune deficiencies
To prevent rhesus disease

10

What is caused by the measles vaccine?

SSPE

11

What is the marker for memory b cells?

CD27

12

What is the marker for memory T cells?

CD45

13

What are the 6 types of vaccine?

Killed whole pathogen
Live attenuated
Sub unit
Synthetic
Toxoid
Conjugate

14

What is an attenuated pathogen?

Made unable to grow in the human body or grow slowly

15

What is the function of adjuvants?

Increase the immune response

16

What adjuvant is used in viral vaccines?

IL33

17

How does HIV enter T cells?

Gp120 on HIV binds CD4

18

What are the problems associated with a HIV infection?

Antibodies against gp120 can enhance infection in macrophages

Antigenic drift

Initial infection is transmitted by infected cell not by free virus

19

What are 5 types of immunodeficiencies?

X linked agammablobulinemia
ADA SCID
MHC deficiency
Ig deficiency
T cell deficiency

20

What are treatments for immunodeficiencies?

Prophylactic antibiotics
PEGAylated ADA injections
HSCT
Gene therapy
Pooled gamma globulin

21

What mutation is associated with x linked agammaglobulinemia?

Btk which causes mutational arrest of B cells

22

What are 3 contributory causes of MS?

Vitamin D
EBV infection
Genetics

23

What gene is associated with MS?

HLA-DRB1

24

What are the antigens in MS?

MBP
MOG
PLP

25

What is the pathophysiology of MS?

CD4 T cells are activated by APC, they express VLA4 so can cross the blood brain barrier. T cells cause inflammation with leads to demyelination. Increased levels of IgG and leukocytes are found in the cerebrospinal fluid

26

How does a decrease in vitamin D cause MS?

Increases inflammation. Less vitamin D = more Th1 response

27

What treatments are available for MS?

Interferon beta (inhibits IFN gamma)

Corticosteroids

Antibody therapies (rituximab against b cells and natalizumab against VLA4)

Methrotrexate

Cyclophosphamide (promotes Th2 response and is toxic to proliferating cells)

28

What does the classical complement system recognise?

Antibody:antigen complexes

29

What does the MBP/lectin system recognise?

Sugar residues

30

What does the alternative pathway recognise?

Pathogen surfaces

31

What is the result of all 3 pathways?

Production of C5 convertase and MAC

32

Why does complement have to be regulated?

To prevent it attacking host membranes

33

What regulates complement?

C1 disrupters
C3 convertase disrupters
MAC inhibitors

34

Common pathway

C3 + C3 convertase = C5 convertase
C5 convertase is cleaved to form C5a and C5b. C5b directs the MAC.

35

MAC

C5b binds C6 and C7 which then binds to the pathogen membrane. C8 binds to the complex and inserts into the membrane. Many molecules of C9 bind to form a pore

36

What activates phagocytes?

Complement
Antigen antibody complexes
Stranger signals
Danger signals

37

Example of stranger signal

Bacterial flagella

38

Example of danger signal

Uric acid from breakdown of purines in dying cells

39

How do phagocytes kill bacteria?

Respiratory burst

40

Where in a phagocyte are bacteria digested?

Phagosomal lysosomal compartment

41

What is respiratory burst?

How phagocytes kill bacteria. It consumes oxygen and is initiated by NADPH oxidase

42

How does the respiratory burst kill bacteria?

Production of ROS

43

What diseases are associated with phagocytosis?

Chediak higashi syndrome
Leukocyte adhesion deficiency
Chronic granulomatous disease

44

What is chediak higashi syndrome?

Improper phagosomal lysosomal function

45

Leukocyte adhesion deficiency

Prevents phagocytes migrating

46

Describe the structure of an antibody

Two light chains
Two heavy chains
Variable region with 2 antigen binding sites
Constant (Fc) region

47

What are the types of immunoglobulin in order of abundance?

IgG IgA IgM IgD IgE

48

Where are IgM and IgG found?

Serum

49

Where is IgA found?

Mucosa

50

Where is IgD found?

Restricted to the B cell membrane - is a B cell receptor

51

What is the role of IgE?

Activates mast cells

52

How is antibody diversity achieved?

Combinatorial diversity

53

How are antibody light chains produced?

Combining V J C gene segments

54

How are antibody heavy chains produced?

Combining VDJC gene segments (D = diversity)

55

What controls gene rearrangement in immunoglobulin?

Rag 1 and rag 2 recombinase

56

What do mutations in RAG genes lead to?

Omenn syndrome (severe immunodeficiency)

57

How do B cells change the sub-type of antibody?

Class switching

58

What is the role of AID

Controls somatic hypermutation in antibody genes. This can increase antibody affinity

59

Describe MHC I antigen processing

Cytosolic proteins are degraded by the proteasome, transported to ER by tap, trimmed by ER peptidases, loaded onto the binding groove of MHC I which is then trafficked to the cell membrane

60

What are CD1 molecules?

Bind non-self glycolipids and present them to T cell receptors on NK cells

61

Describe MHC class II antigen processing

MHC II assembles as heterodimers in the ER. Invariant chain binds to the peptide binding groove. Transported to an endocytic vesicle which is acidified to cleave invariant chain to CLIP. Engulfed pathogen proteins are degraded by the proteasome and bind to the peptide binding groove thanks to HLADM. MHC is then trafficked to the cell surface.

62

Where are T cells selected?

Thymus

63

What are CD4 T cells?

Helper T cells (provide help to B cells)

64

What are CD8 T cells?

Kill virally infected cells

65

What are Tregs

T cells which modulate the immune system

66

What happens when the T cell receptor is stimulated?

The T cell divides to produce clones with the same T cell receptor specificity

67

T cell receptor genes

VJC for the alpha chain
VDJC for the beta chain

68

How are T cell receptor genes rearranged?

Rag dependent mechanism

69

What coreceptor does the T cell receptor require?

CD3

70

What co receptor does the B cell require?

Ig alpha beta heterodimer

71

Which cytokine stimulates T cell clone expansion?

IL2

72

What is the role of interferon gamma?

Suppresses viral infection of cells

73

What releases IL1 and TNF alpha

Macrophages

74

TNF alpha receptor pathway

Signals through MAP kinase or ERK kinase to activate NFkB

75

Il1 signalling pathway

Signals through MyD88 and IRAK kinase

76

How do T reg cells maintain peripheral tolerance?

Secrete cytokines that inhibit autoreactive T helper cells

77

Autograft

Transplant from recipients own tissues

78

Allograft

Transplant from non-identical members of the same species

79

Isograft

Transplant from genetically identical individuals (monozygotic twins)

80

Xenograft

Transplant from different species

81

Hyperacute rejection

Rejection within minutes of transplant

82

Acute rejection

Rejection within 2 weeks of transplant due to MHC mismatch

83

Chronic rejection

Months to years after transplant, mechanism unknown

84

Which immunosuppressant drugs are used in transplants?

Cyclosporin A
Rapamycin
FK506

85

How do immunosuppressant drugs for transplant work?

Block IL2 production
Block T cell cell cycle