Introduction to B cells and Antibodies Flashcards

1
Q

What is IgD?

A

Antigen receptor virgin B cells

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2
Q

What is IgM?

A

Agglutinin - activates complement

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3
Q

What is IgG?

A

Opsonin - activates complement

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4
Q

What is IgA?

A

Secretory - protects mucosa

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5
Q

What is IgE?

A

Protection vs helminths

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6
Q

List some Complements?

A

Cytolysis, Chemotaxis, Inflammation, Oposonisation

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7
Q

Where are B cells?

A

Stay in lymph tissue and respond to antigens by differentiating into plasma cells

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8
Q

How are B cells activated?

A

B cell receptors binding to specific antigents

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9
Q

What do B cells in lymph tissue respond to?

A

Unprocessed antigents or antigens presented

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10
Q

How do B cells secrete antibodie?

A

Once activated enlarge and differentiate into plasma cells

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11
Q

What are antibodies?

A

4 polypeptide chains, 2 identical heavy and 2 identical light

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12
Q

What are Heavy AA chains made up on?

A

450 AA

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13
Q

What are light chains made up of?

A

220 AA

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14
Q

How is light chain bound to a heavy chain?

A

By a disulphide bond

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15
Q

How are 2 heavy chains held together at mid-region?

A

2 disullphide bonds forms hinge region

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16
Q

What regions do both light and heavy chains posses?

A

V and C regions

Variable , constant

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17
Q

What is the Variable region?

A

Confer specificity of antibody, found at tips of H and I chains on antibody arms

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18
Q

What is Constant region?

A

Same in different antibodies and consist of H and L chains not associated with antigen binding

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19
Q

What does Binding of antigen binding site with antigen cause?

A

Neutralization, Agglutination, Precipitation

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20
Q

What is Neutralization?

A

Antibody covers bio active part of microbe

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21
Q

What is Agglutination?

A

Antibody cross links forming a clump

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22
Q

What is Precipitation?

A

Antibody cross links forming insoluble antigen antibody complex

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23
Q

Exposed FC portion following antigen binding promotes what?

A

Complement fixation, Opsonisation, Activation of NK cells

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24
Q

What is complement fixation?

A

FC of antibody complement protein activates

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25
Q

What is Opsonization?

A

FC region of antibody binds to receptors of phagocytic cells

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26
Q

What is activation of NK cells?

A

FC region binds to NK cells trigger TC chemical

27
Q

What is a Complement?

A

Complex system of number of serum proteins act in a sequence in humoral defence against extracell microorgs

28
Q

What are complement proteins?

A

C1-9

29
Q

What are Complement factors?

A

D,B,Properdie

30
Q

What are Complement receptors?

A

C1-3 - control proteins

31
Q

What does Antibody bind to? IGM/IGG?

A

Epitopes of antigen

32
Q

What does C1 bind to?

A

Fc region of antibodies

33
Q

What does C1r activate?

A

C1s which is proteinase

34
Q

What does C1s cleave?

A

C4

35
Q

What does C4b bind to?

A

Antigen whilst C4a stays in fluid

36
Q

What does C1 cleave?

A

C2

37
Q

What does C2b bid to?

A

Antigen and c2a in fluid

38
Q

What is C2b?

A

Proteinase cleaves C3

39
Q

What does C3b bind to?

A

Antigen and c3a in fluid

40
Q

What does c2b cleave?

A

C5

41
Q

What happens to C5?

A

Doesnt bind, c5a in fluid

42
Q

What does C5b bind?

A

C678 in fluid

43
Q

What does C5b678 bind to?

A

Lipid bilayer

44
Q

What does C9 do?

A

Inserts hole into membrane

45
Q

What is microorg lysed by?

A

Membrane attack complex

46
Q

Why are MACS deposited into bilayer of antigens?

A

Complement is enzymatic and cleave its substrate

47
Q

What is an e.g of MAC?

A

E.coli

48
Q

What does MAC do?

A

Form pores in lipid bilayer to kill gram negative bacteria

49
Q

What happens to gram positive bacteria in MAC?

A

Protect themselves from complement mediated lysis by thick peptidoglycan wall

50
Q

How do Funghi protect from MAC?

A

From complement mediated lysis by thick chitin cell walls

51
Q

Where does Gram positive pathway end?

A

C5 cleavage

52
Q

What are C3a and C5a?

A

Anaphylatoxins - activate mast cells

Chemotaxins - attract phagocytes

53
Q

What is C3b?

A

Opsonin - enables phagocytes to recognise and bind to antigens

54
Q

What is the alternative pathway?

A

Innate immunity with factors B,D,P activating enzymes

55
Q

What is hyperacute rejection mediated by?

A

Naturally occuring antibodies to a-Gal

56
Q

What is a-Gal?

A

Synthesised by a1,3Galactosyltransferase

57
Q

What do humans express a-Gal as?

A

Foreign and it is an epitope and have high titres of antibodies in gut

58
Q

Why are organs rejected?

A

Antibodies enter donor blood vessels and bind to a-Gal epitopes on endothelial cells, activating complement and neutrophils attracted, thromus blocks vessels, organ has no o2 and dies

59
Q

What is hyper acute?

A

Preformed antibodies to Gal-a1 and Gal epitope

60
Q

What is acute?

A

Direct pathway of immune recognition incompatible MHC II

Indirect pathway incompatible MHC I

61
Q

What is the antibody titre?

A

measureof immunological memory

62
Q

What is initial contact with antigen called?

A

Primary response

63
Q

What is a second encounter with same antigen called?

A

Secondary response producing vast amount of IgG antibodies

64
Q

Why does Age affect immunity?

A

Low levels of immune function, T cells less responsive to antigents