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Year 1 (PCS & Cases 1-6) > Immunology > Flashcards

Immunology Flashcards

1
Q

What antibody is most effective in activating complement? Why?

A

IgM.

Pentameric antibody so it has the largest surface area.

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2
Q

What is the first antibody secreted after encounter with an antigen?

A

IgM

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3
Q

What does “ MHC is polygenic” mean?

A

It contains several different MHC class I and class II genes. Every individual possesses a set of MHC molecules with different peptide binding clefts.

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4
Q

What does “ MHC is polymorphic” mean?

A

There are multiple variants (alleles) of each gene within the population as a whole.

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5
Q

Name the three ‘major’ immunoglobulins.

A

IgM, IgG, IgA

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6
Q

Name the Penatmeric, Dimeric and Monomeric antibodies.

A

Pentameric - IgM

Dimeric - IgA

Monomeric - IgG, IgD, IgE

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7
Q

What are Langerhans cells?

A

Dendritic cells found on the skin

(majority found in the stratum spinosum)

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8
Q

What activates

a) classical pathway?
b) lectin pathway?
c) alternative pathway?

A

a) IgM, IgG, CRP
b) manose binding lectin binding to the pathogen
c) triggered by changes in the environment due to the pathogen.

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9
Q

Name the anaphylatoxins.

A

C3a and C5a.

Cause degranulation of mast cells.

Also cause bronchoconstriction & vasodilation.

Attract and activate n’s and m’ to site of injury.

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10
Q

What do the three pathways converge on?

A

Activation of C3

Generation of C5 convertase

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11
Q

What does C5 convertase do?

A

Splits C5 into

C5a - chemotactic agent

C5b - remains attached to the pathogen and begins the terminal pathway to create MAC.

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12
Q

What are the three final outcomes for the complement system?

A
  1. Chemotaxis = recruitment of inflammatory cells.
  2. opsonisation (via C3b and C4b) for phagocytosis.
  3. cell lysis - via MAC.

All result in death of the pathogen.

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13
Q

What are the two types of MHCs?

What does each do?

A

Type 1 and type 2.

[1] –> presents antigens from intracellular pathogens e.g. virsues to cytotoxic T cells.

[2] –> presents antigens from extracellular pathogens e.g. bacteria to T helper cells.

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14
Q

How MHC 1 and 2 differ in structure?

A

MHC 1

1 large polypeptide that contains three extracellular domains which is anchored to the plasma membrane. The smaller polypeptide is not anchored.

MHC 2

2 large polypeptides with two extracellular domains which are both anchored to the plasma membrane.

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15
Q

How can a cytotoxic T cell be distinguished from a T helper cell?

A

cytotoxic T cell express the protein CD 8

T helper cell express the protein CD 4

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16
Q

What are CD4 and CD8 molecules called?

Where do they bind?

A

T cell ‘co’ receptors.

CD4 binds to a site on the MHC 2 molecle that is separate from the binding site of the T cell receptor.

CD8 binds to a site on the MHC 1 molecle that is separate from the binding site of the T cell receptor.

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17
Q

What is the outcome for

CD8 T cell + virus infected cell?

A

death of virus infected cell

18
Q

What is the outcome for

CD4 T cell + macrophage?

A

The macrophage is involved in pahocytosis of the bacteria already. Binding of CD4 T cell improves the phagocytic activity of the macrophage causing cytokines to be released.

19
Q

What is the outcome for

CD4 T cell + B cell?

A

The B cell has its antigen bound. It causes secretion of cytokines which cause B cells to differentiate into antibody secreting plasma cells.

20
Q

The antigen binding site of an immunoglobulin is formed from __ ?

A

The paired V regions of a single heavy chain and a single light chain.

21
Q

What is the hypervariable region?

A

Located within the variable region - vaires greatly between different antibodies.

22
Q

What is the constant region?

A

The most conserved region of the molecule with limited variation between antibodies.

23
Q

Which diagram represents

a) CD4 and MHC 2
b) CD8 and MHC 1

A
24
Q

What properties are linked to IgA?

(hint: 2 )

A

5,9

25
Q

What properties are linked to IgD?

(hint: 1)

A

7

26
Q

What properties are linked to IgE?

(hint: 2)

A

6,7

27
Q

What properties are linked to IgG?

(hint: 6)

A

1,2,3,4,6,8

28
Q

What properties are linked to IgM?

(hint: 1)

A

2

29
Q

Mucosal epithelia of the GI tract, respiratory tract etc is protected by what?

A

dimeric IgA

30
Q

Give some examples of passive transfer of immunity.

A
  1. transfter if IgG across the placenta during foetal development.
  2. transfer of IgA through breast milk.
  3. intravenous immunoglobulin therapy for immunocompromised individuals.
31
Q

What type of bacteria is Clostridium difficile?

A

Gram positive

bacillus

anaerobic

32
Q

What complement proteins make up C3 convertase?

(two options)

What happns to C3 convertase after this?

A

C3bBb (from alternative pw)

C4bC2a (from classical/MBL)

Cleaves C3 –> C3a and C3b

In alternative, C3bBb + C3b = C3bBb3b (C5 convertase) –> C5b & C6-9 –> MAC

In classical/MBL, C4bC2a + C3b = C4bC2a3b (C5 convertase)

33
Q

What factor is required for cross linking of fibrin monomers?

Fibrinpeptide A release forms __?

Fibrinpeptide B release forms __?

A

Factor 13 ( –> F13a)

Fibrinogen -> Fibrin monomers -> Polymer

*F13a* -> Cross linked fibrin polymer

Fibrinpeptide A release forms proteofibrils

Fibrinpeptide B release forms side to side polymer

34
Q

What do these serologic tests conclude about whether or not this person is / has been affected by Hep B?

A

They are SUSCEPTIBLE.

Haven’t been vaccinated or infected in the past (therefore no natural immunity)

35
Q

What do these serologic tests conclude about whether or not this person is / has been affected by Hep B?

A

They are IMMUNE due to natural infection.

The anti-HBc represents past infection.

36
Q

What do these serologic tests conclude about whether or not this person is / has been affected by Hep B?

A

They are IMMUNE due to the hep B vaccine.

The hep B vaccine gives you the surface antibody.

37
Q

What do these serologic tests conclude about whether or not this person is / has been affected by Hep B?

A

They are ACUTELY INFECTED.

38
Q

What do these serologic tests conclude about whether or not this person is / has been affected by Hep B?

A

They are CHRONICALLY INFECTED.

39
Q

What is the hepatitis B surface antigen?

HBsAg

A

A protein on the surface of the hep B virus.

The presence of it indicates acute / chronic infection.

The body usually produces antibodies in repsonse.

The HBsAg is used to make the Hep B Vaccine.

40
Q

What is the Hepatitis B surface antibody?

anti-HBs

A

Its presence indicates

a) recovery and hence natural imunity has developed from the Hep B virus OR
b) the person has been vaccinated.

41
Q

What is the Hepatitis B core antibody?

anti-HBc

A

Its presence indicates

a) previous OR
b) ongoing infection.

42
Q

What does a positive result of the IgM antibody to hepatitis B core antigen mean?

IgM anti-HBc

A

A positive result indicates recent / acute infection.

Year 1 (PCS & Cases 1-6) (13 decks)

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