Lecture 4: Components of the immune system 2 Flashcards Preview

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Flashcards in Lecture 4: Components of the immune system 2 Deck (41)
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1
Q

List the primary and secondary lymphoid organs;

A

1) Bone marrow and Thymus

2) NALT
SALT (Skin)
BALT (bronchus)
GALT (payers patches, appendix)
Lymph nodes
2
Q

Describe drainage of lymph into the blood

A

Rest of body -> Thoracic duct -> Left subclavian vein

Top right quadrant -> Right subclavian vein

3
Q

Describe DC function in lymphoid organs;

A

DC take up antigens from the blood and present them to naive T and B cells.

4
Q

During central tolerance what can happen if a B cell is self reactive?

A

Immunoglobulin/receptor gene can be rearranged and the receptor can be tested again. If it continues to self react then it is destroyed.

5
Q

What is a lymphoid tissue?

A

A tissue in which lymphocytes are found

6
Q

What are lymphoid tissues usually?

A

Lymphoid tissues are usually groups of follicles that are surrounded or encapsulated by specialised supporting tissues or membranes.

7
Q

Describe B cell arrangement in lymph nodes;

A

B lymphocytes are localized in the follicles

8
Q

Describe t cell organization in lymph noes;

A

T lymphocytes are more diffusely distributed in the surrounding paracortical areas

9
Q

What is also found in B cell follicles?

A

Follicular DC that distribute antigens between neighbouring follicles

10
Q

What happens if a B cell in a follicle becomes activated?

A

The rest of the B cells move to the edge of the follicle

11
Q

What occurs at the center of some B cell follicles?

A

B cell follicles contain germinal centres where B cells undergo intense proliferation after encountering their specific antigen and their co-operating T cell.

12
Q

Describe Th and B cell interplay.

A

B cell with antigen receives signals from Th (reassurance) which allows it to undergo proliferation

13
Q

Describe B cell and its changing follicular structure in lymph nodes;

A
Primary follicle (naive B cells)
- Activation of some B cells in presence of Th cells.
Secondary follicle (has Mantle of naive B cells)

This forms a germinal centre

14
Q

What happens in a germinal center?

A

Essentially describes the proliferation of activated B cells

  • Can be divided into light and dark regions.

Starting in the dark region;

  • activated B cell forms proliferating centeroblasts
  • These undergo somatic hypermutation (receptors gain high affinity)
  • These centerocytes migrate to the light center where they undergo negative selection, those that self react are phagocytosed my macrophages.
  • Those that dont self react, differentiate into memory cells and plasma B cells.
15
Q

What are some extra features of lymph nodes that were not mentioned previously;

A
  • Medullary sinus
  • Medullary cords (macrophages and plasma cells)
  • Marginal sinus (surrounds lymph node)
16
Q

Describe the spleen;

A
  • Fist sized organ
  • Collects antigen from blood
  • Disposes of senescent RBC
17
Q

Describe the spleens colouring

A

Mostly Red pulp
Lymphocytes surround the arterioles entering the spleen and form white pulp

White pulp inner region is the peri-arteriolar lymphoid sheath (PALs)

18
Q

Whats in PALs?

A

Containing mainly T cells and the flanking region termed the B cell corona

19
Q

What is GALT?

A

Git associated lymphoid tissue

Inc; Tonsils, appendix, adenoids, peyers patches in SI

20
Q

What is the function of GALT?

A

To collect antigen from epithelial surfaces of the GI tract

21
Q

Whats important about payers patches?

A

Most highly organised of these tissues

Antigen is collected by special cells called multifenestrated or M cells (uses trancytosis to collect antigens)

22
Q

Gives some notes about the thymus and T cell development;

A

CLPs enter the thymus and undergoes thymic selection (+ive and -ive)

23
Q

Describe thymic selection;

A

Two parts +ive and -ive selection ( you should know this by now)

1% thymocytes survive selection

Therefore thymus is significant for T cell proliferation and apoptosis.

Thymic epithelium plays a role in selection mediated by various cytokines

24
Q

Describe the anatomy of the thymus

A

Capsule
Cortical epithelium
Hassals corpuscle
Medullary epithelium

Cells;
Thymocyte precursors
Dividing thymocytes
Maturing thymocyte
DC
macrophage
25
Q

What is hassals corpuscle?

A

Distinct medullary feature, unknown function although can contain KT cells.

26
Q

Describe thymocyte migration

A
SUBCAPSULAR REGION
- Immature double negative CD3,4,8 thymocytes
CORTEX
- Immature CD3,4,8 double positive thymocytes
CORTICOMEDULLARY JUNCTION
- Mature CD4 (Th) and CD8(Tk) cells
MEDULLA
- Venules
27
Q

Describe thymocyte epithelial interplay structurally

A

Epithelial cells of the thymus form a network around the developing thymocytes.

Close for selection

28
Q

B cell function and receptors

A

Antibody production

CD 19,20

29
Q

CTL function and receptors

A

Cytotoxic cells CD8

30
Q

NK/K cells function and receptors

A

Natural Killer cell
Early anti-viral defence
Antibody dependant cell mediated cytotoxicity

CD 3 Negative
CD 16
CD56

31
Q

Th cell function and receptors

A

Regulator
Induction of effector cells (B, CTL, NK)

CD4

32
Q

Whats the most common cellular receptor?for lymphocytes?

A

CD3

33
Q

Whats the receptor for haemopeotic cells?

A

CD34

34
Q

DC receptors

A

CD11 Hi

CD 123 low

35
Q

pDC receptors

A

CD 123 hi

CD 11 negative

36
Q

Neutrophil receptors;

A

CD 16, 66 +

37
Q

Basophil receptors :

A

CD 123+

38
Q

Eosinophil receptors :

A

CD 66 +

CD 16-

39
Q

Monocyte receptor

A

CD 14

40
Q

What is CD?

A

Can be:

  • Receptor
  • Glycolipid
  • Lots of differing functions
41
Q

Describe immunotyping blood

A

1) Get blood sample
2) Seperate mononuclear cells using ficoll gradient
3) Fluoresce with antibody
4) Pass stained sample through laser beam
5) Get cell populations of interest