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Immunology > Acquired > Flashcards

Acquired Flashcards

1
Q

Cells of lymphoid cycstem

A

T (CD4 and CD8)
B
NK

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2
Q

What is the process of formaiton of T cells

A

Produced in bone marrow
Migrate to Thymus where they mature

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3
Q

How do T cells mature?

A

Development of T cell receptor
- Cell surface bound protein structure that binds to antigen

TCR binding results in T cell activation and proliferation

TCR testing in thymus - if autoactive - rearrange TCR or undergo apoptosis (clonal deletion)

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4
Q

What can activate a T cell

A

MHC antigens
Antigen presenting cells
Antigen processing

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5
Q

What are MHC class I cells? What do they present to?

A

Expressed on all cells

Present to CD8+ T cells

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6
Q

What are MHC class II cells? What do they present to?

A

Expressed on selected cells such as APCs

Present to CD4+ T cells

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7
Q

What are MHC antigens called in uhmans?

A

HLA human leukocyte antigens

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8
Q

What do MHC class I cells do

A

Found on all cells and continuously present broken down peptides .
Constantly proving to the immune system that it is a healthy cell

If a cell becomes infected or a tumour it will start presenting foreign peptides on MHC I molecules stimulating CD8 cells to destroy it

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9
Q

What is cross presentation

A

Presentation of exogenous material on MHC I receptor

Occurs when APC takes up a cell that contains foreign antigen

Material broken down and presented on MHC II receptor but some debris peptide enters cytoplasm and this is presented on MHC I

CD8 activated and responds

MEchanism of graft rejection

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10
Q

What are MHC class II molecules?

A

Presented by specialised APCs which take up exogenous pathogens, phagocytose them and present peptide products.

MHC II molecule bind with peptide and travel to cells urface

Antigen/MHC presented to T lymphocytes

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11
Q

How does MHC maximise immunity?

A

Polygenic - several different MHC class I and II genes

Polymorphic - multiple variants of each gene increasing potential number of peptide combinations that can be presented

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12
Q

What is alloreactivity?

A

Recognition of non-self tissue from the same species as foreign

2 methods:
1. Recognition of foreign HLA molecule
2. Recognition of presented tissue derived peptide as pathogenic

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13
Q

What are APCs

A

Dendritic cells
- Myeloid - produce IL12
-Plasmycytoid produce IFN 1

MAcrophages

B cells

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14
Q

CD8 vs CD4 T cells

A

CD8 recognise MHS class I molecules presented antigens

CD4 recognise MHC class II presented antigens

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15
Q

What do CD8 T cell granules contain

A

Membrane disrupting proteins - perforin, granulysin
Serine proteases - granzymes

Lysosomal eznumes

Stored effector molecules - FasL - binds to Fas expressing cells to induce apoptosis

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16
Q

What in the role of CD4 cells?

A

Secreting cytokines to upregulate responses

17
Q

What do Th1 cells secrete?

A

IFN - gamma
- Activates macrophages, enhancing antigen presentation to T cells, increasing phagocytosis

IL-12
Drive DC activation and presenation

Express CD40 stimulatory molecule - amplifies response

18
Q

What do Th2 cells secrete

A

IL4, IL5 IL6

IL13
Stimulate antibody production and mucous secretion

19
Q

What do Th17 cells secrete

A

IL17

20
Q

What CD4 cells are involved in allergy and parasitic infections

A

Th2

21
Q

What is IL 17

A

Potent neutrophil chemoattractant

22
Q

What is a cytokine

A

Cell derived soluble mediator

23
Q

What are anti inflammatory cytokines?

A

IL10
TGF beta

Downregulate CD4 cell responses

IL4 (antagonises IFN-ga)

24
Q

What are functions of cytokines?

A

Cytotoxic - TNFa
Growth factors - IL4 for B cells
Synergistic to enhance response - IL1 enhances IL8
Clonally expanding cells - IL2 promotes expansion of activated CD4
Cell attractants/chemokines IL8 attracts neutrophils

25
Q

What are effects of TNFa

A

Pro-inflammatory

Activate PolyMorphoNuclear leucoytes
Cytotoxic for target cell
Antiviral properties
Anticoagulant
Modulate haematopoiesis

p55 and p75 receptors

26
Q

Function of IL1

A

Raise body temperature in response to infectionW

27
Q

Wat is the function of IL2

A

Clonal expansion of activated R cell

28
Q

What is the function of IL4

A

Th2 cytokine secreted by mast cells and Th2 cells

Activates B cells to differentiation for the process of antibody production

29
Q

What is the function of IL8

A

Chemokine
Attracts neutrophils

SEcreted by monocytes, macrophages, T cells, epithelial cells

30
Q

What are interferons?

A

Pro inflammatory
Immunomodulatory

Antiviral

IFN alpha/beta
Can be used in chronic hepatitis and MS

IFN gamma upregulates expression of MHC class II on cells secreted by Th1
Activates macrophages and induces NK activity

31
Q

Formation of B cells

A

Derived from haemopoietic stem cells in bone marrow
Mature in Bone marrow

Undergo gene rearrangement and receptor testing for autoantigen specificity

  • if autoactive - gene editing by RAG genes or clonal deletion
32
Q

What happens when B cells are activated

A

Mature into
Plasma cells
Memory cells

33
Q

What is the function of plasma cells

A

Produce antibodies

  • bind to pathogen and disable
  • opsonize pathogen for phagocytosisW
34
Q

5 classes of antibody

A

IgA, IgD, IgE, IgG, IgM

35
Q

What is structure of antibody?

A

Y shaped
two heavy chains and two light chains

Variable region at two distal arms of Y which bind to antigen

Constant region that does not bind - activates effector cells and complement

36
Q

What fragments can Ig be cleaved into ? Enzyme?

A

Papa-in

Fab fragments - antigen binding containing V variable region

Fc fragments - crystallizable and contain C constant region

37
Q

How can B cells be activated

A

B cell takes up foreign material and presents it on MHC II antigens
Activated Th2 cell recognises peptide and releases IL4 - activates B cell

Unprocessed antigens (Thymus independent antigens) - significant cross linking of B cell receptors

38
Q

What is affinity maturation

A

Increased affinity for antigen presented results in proliferation of B cell and production of new antibody

B cell that has reduced affinity will lack stimulation and will undergo apoptosis

39
Q

What is the first antibody produced by plasma cell?

A

IgM

Immunology (6 decks)

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