Lecture 9.2: Adaptive Immunity Flashcards

1
Q

Adaptive Immunity

A

• Immunity established to adapt to infection
• Learnt by experience.
• Confers antigen-specific immunity
• Enhanced by second exposure
• Memory
• Ineffective without innate immunity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Types of Adaptive Immunity (2)

A

Humoral
Cell Mediated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Adaptive Immunity: Humoral and Cell-Mediated

A

• Mediated by T and B lymphocytes, NKT cells
• Provides defence against both intracellular and extracellular antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Adaptive Immunity: Humoral

A

• Antibodies produced by B lymphocytes (circulation and mucosal fluids)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Adaptive Immunity: Cell-Mediated

A

• Phagocytes are activated
• Cytotoxic T cells interact with pathogenic cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do T and B cell specificities differ?

A

• T cells only recognise proteins
• B cells recognise proteins, carbohydrates, nucleic acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Natural Killer T Cells

A

• Recognise IgG, lipids, MHC class I, secrete cytokines (IFN, TNF, IL12)
• Kill tumour cells and virally infected cells
• Induce apoptosis by pumping proteases through target cell membrane
• Like DC cells, NKT cells determine the type of adaptive response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does CD stand for?

A

Cluster of Differentiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

T-Cells: CD8+

A

Cytotoxic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

T-Cells: CD4+

A

Helper

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does Antigen Recognition rely on?

A

It relies on presentation of antigens by cells of the innate immune system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Antigen Recognition

A

• Antigen presenting cells (APCs) take up antigen (peptide fragment presented)
• Cells divide, form clones of cells that respond to antigen (clonal selection)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Effector Cells and Negative Selection

A

Effector cells subject to negative selection (autoimmune disease) where cells expressing ‘self’ are destroyed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is antigen repertoire developed?

A

Repertoire develops without exposure to antigen through stem pcell differentiation

Repertoire present before encounter with antigen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Naive T Cell

A

A T cell that has matured and been released by the thymus but has not yet encountered its corresponding antigen

Express antigen receptors

Do not eliminate antigen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Effector Cell

A

Differentiated progeny of naive cells after antigen exposure

Cells produce molecules to eliminate antigen

17
Q

Memory T and B cells

A

Following antigen exposure, activated T and B cells persist as memory cells

Memory cells are close to sites of reinfection for rapidity of response

18
Q

Phases of the Adaptive Response

A

Antigen Recognition
Lymphocyte Activation: Clonal Expansion of T and B Cells
Antigen Elimination: Humoral and Cell Mediated
Contraction (Homeostasis): Apoptosis
Memory: Memory Cells Endure

19
Q

Where are Antigen Presenting Cells (APCs) found?

A

• Skin (SALT)
• Mucous membranes (GALT, NALT, BALT)
• Lymphoid organs (Lymph nodes, spleen)
• Blood circulation (plasmacytoid and myeloid dendritic cells)

20
Q

Phagocytosis

A

Captures whole microbe

21
Q

Macropinocytosis

A

Capture of soluble particles from pathogen

22
Q

What is a PRR

A

Pattern Recognition Receptors
Diversity in pathogen sensors (PRRs) is a feature of APCs

23
Q

What antigens to TCRs and BCRs bind to?

A

TCRs and BCRs bind antigens presented by MHC molecules

24
Q

What 2 signals are required to activate lymphocytes (for proliferation)?

A

• TCR
• Verification signal

25
Lymphoid Tissue Activation
In lymphoid tissue naive CD4 or CD8 proliferate and differentiate
26
Peripheral Tissue Activation
In peripheral tissue CD4 effectors activate macrophages and B cells, whilst CD8 cells kill infected ‘target cells’ and activate macrophages
27
Delayed Type Hypersensitivity
Th1 and Th17 are involved in DTH reactions to antigens
28
Helper T cells (CD4+)
• Activate other cells • Macrophages containing microbes • B cell class switching
29
Cytotoxic T cells (CD8+)
• Kill cells expressing recognised abnormal antigens • Normal cells containing viruses • Mutated/Cancerous cells
30
Effector Mechanisms T Cell Responses: Extracellular Microbes
Eosinophils: Killing of Parasites B-Cells: Antibodies Mast Cells: Local Inflammation Allergies (IgE) Neutrophils: Phagocytosis which leads to autoimmunity
31
Effector Mechanisms T Cell Responses: Intracellular Microbes
CD8+: Cytotoxic T Lymphocyte, release perforins granzymes B-Cells (Isotype Switching): Antibodies (IgG2-3) Macrophages: Phagocytic activities, Kill opsonized microbes, Autoimmunity, chronic inflammation
32
Antibody Structure
Heavy Chains Inside Light Chains Outside Fab: Variable Region specific to antigens Fc: Invariable region of antibody
33
Importance of Fc Region on Antibody
Fc region of antibody attracts NK cells and phagocytes
34
B-Cell Memory Development
After isotype switching, B cells continue maturation to improve specificity to antigen High affinity, class switched B cells become memory cells Migrate to sites of pathogen entry
35
Contraction
• Elimination of microbes = loss of activation signals • Treg cell signalling outweighs activation signals • Reduction in response, apoptosis of phagocytes • Surviving lymphocytes are memory cells
36
T-Cell Memory
Multiple cell types in different locations with different groups of CD surface markers (lymph nodes, circulation, MALTs) Pool of memory cells determined by future exposure TCRs recognising conserved regions more likely to remain long term Converted to effector cells on second encounter with antigen that binds receptor
37
Characteristics of the Memory Response (6)
Faster Stronger Longer Duration Higher Affinity Isotype Switch Affinity Maturation Use Th Cells