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Immunology > Lecture 14 - Functional Lymphoid Anatomy - FINAL > Flashcards

Lecture 14 - Functional Lymphoid Anatomy - FINAL Flashcards

1
Q

What are the 7 important lymphoid tissues?

A
  1. Adenoid
  2. Tonsils
  3. Lymph Node
  4. Spleen
  5. Peyer’s Patch in Gut
  6. Bone Marrow
  7. Thymus
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2
Q

What are the 4 purposes of lymphoid tissues?

A
  1. Supports lymphopoiesis
  2. Supports development of incredibly diverse repertoire of antigen-specific lymphocytes
  3. Critically important for both central & peripheral tolerance
  4. Provides sustaining signals for lymphocyte survival
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3
Q

Which of the following are central lymphoid and which are peripheral lymphoid tissues?

  1. Lymph node
  2. Thymus
  3. Spleen
  4. Mucosal
  5. Bone marrow
A

Bone Marrow & Thymus = central

the rest are peripheral

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4
Q

Which lymphoid tissue (central or peripheral)

Are responsible for the following:

  1. Lymphopoiesis
  2. Central Tolerance
  3. B cells
  4. T cells
A

CENTRAL

B cells - continually made from bone marrow

T cells migrate to the thymus during embryogenesis to develop there

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5
Q

What are the main functions of the peripheral lymphoid tissues?

A
  1. Mixture of B and T cells
  2. Supports circulating lymphocyte survival
  3. Activation of naïve lymphocytes
  4. Peripheral Tolerance
    - catches any lymphocytes that are auto reactive that may have escaped central tolerance
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6
Q

All lymphocytes develop from HSC in the ______.

T-cell progenitors migrate to the _____.

B-cells develop in the bone marrow

_______ in the bone marrow, are critically important to B cell development

A
  1. Bone Marrow
  2. Thymus
  3. Bone marorw
  4. STROMAL CELLS
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7
Q

What are some areas besides the bone marrow where B cells develop?

A
  1. Fetal Liver

2. Neonatal spleen

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8
Q

Early stem cells hand out where? Where do they move after this?

Progression of B cell development depends on maturation factors provided by the stream cells. Name some examples

A

Early stem cells hang out at the endosteum, just below the inner cavity of the long bones, but then move toward the stromal cells in the trabeculae

  1. such as FLT3 ligand,
    IL-7
    Stem-Cell Factor (SCF)
    CXCL12
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9
Q

As B cells mature they move toward the _____ of the marrow cavity and then into the circulation, heading for what organs?

A
  1. CENTRAL SINUS

2. Peripheral Lymphoid organs

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10
Q

Central tolerance is what?

What happens if an immature B cells meets its antigenic match in the peripheral lymphoid organs?

A

Self-reactive B cells die by apoptosis prior to leaving the bone marrow (central tolerance)

  1. it will mature into antibody producing plasma cells & memory B cells
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11
Q

What are the 2 most important PERIPHERAL ONLY lymphoid structures?

A
  1. Lymphoid follicles

2. Germinal Center

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12
Q

_____ contains only immature thymocytes & scattered macrophages

_____ more mature thymocytes, dendritic cells & macrophages

Mice & Children without thymus do not what?

A

CORTEX

THYMUS

NO THYMUS = NO T CELLS despite lymphoid progenitors

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13
Q

What do thymocytes depend on for survival? Which cytokine?

A
  1. Thymic Epithelial Cells

2. IL- 7

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14
Q

When is the rate of T cell production greatest?

When does it begin to shrink?

A
  1. Before puberty
  2. Begins to shrink after puberty
    - the production of new T cells is lower but not entirely absent
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15
Q

Early on, thymocytes have no surface markers, including the T-cell receptor _____

A

CD3

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16
Q

Further interaction with thymic stromal cells give rise to “double negative” cells, that are (+) for CD3, but lack the _______

A

co-receptors CD4 or CD8

17
Q

When does the beta chain of the TCR rearrange?

When does the alpha chain rearrange?

A

Double Negative phase

When the cell is a DOUBLE POSITIVE

18
Q

T cell central tolerance:

Which cells undergo positive selection?

Negative Selection?

A
  1. DP cells with low affinity for peptide MHC complex will SURVIVE as ISP
  2. Single Positive thymocytes that have high affinity for peptide - MHC will be deleted
19
Q

True or false:Thymic cortical epithelial cells express self peptide in MHC I or MHC II molecules

A

TRUE

20
Q

ANtigens in the lymph notes freely float or are actively brought by APC’s to the node via ____

A

CHEMOKINES

-They are brought to the lymph node by the afferent lymphatics into the paracortical areas

Chemokines also bring in circulating lymphocytes from the blood toward the paracortical area

21
Q

Lymphocytes squeeze out of the vessels through _________ into the paracortical areas

A

High Endothelial Venues

22
Q

What are 2 ways lymphocytes can be activated in the lymph node?

A
  1. Antigen can be brought displayed in MHC of APCs & presented to T-cells
  2. Free antigen can also be captured by LN macrophages & presented directly to follicular B cells, to paracortical T cells & passed to follicular dendritic cells.
23
Q

When they become activated, T cells and B cells both move to the border of the ____ and T-cell zone, & T cells can provide their helper function to B cells

A

Follicle

24
Q

What are the 3 main functions of the spleen?

What is it especially good at doing?

A
  1. Immune responses to blood-borne pathogens (white pulp)
  2. RBC Disposal & Iron recycling (red pulp)
  3. Secondary Hematopoiesis (if needed)
    - Especially good at clearing infections with encapsulated bacteria

Pneumococci Meningococci

25
Q

SPLEEN: WHITE PULP

Organized around _____ which drain into the marginal sinus.

Which zone has special B cells & macrophages?

What are these cells sensitive to?

A
  1. CENTRAL ARTERIOLES
  2. MARGINAL ZONE
  3. These cells are sensitive to bacterial polysaccharides & other circulating peptides
26
Q

Blood antigens are brought to the marginal sinus by ______ or sampled by marginal zone macrophages

A

circulating dendritic cells

27
Q

Lymphoid organs also undergo CENTRAL tolerance. True or False.

A

FALSE

28
Q

What is peripheral tolerance?

A

PERIPHERAL TOLERANCE

In the absence of an infection, mature B & T cells that encounter a strongly cross-linking antigen in the peripheral lymphoid organs will undergo clonal deletion or anergy

29
Q

What are 2 additional lymphoid organ functions?

A
  1. Peripheral tolerance

2. Lymphocyte homeostasis

30
Q

What is lymphocyte homeostasis?

A
  1. Signals & Cytokines in Lymphoid Organs are crucial for maintenance of naïve & memory lymphocytes
  2. Repeated contacts with self-peptide:self-MHC provides a sort of continual peripheral positive selection for T-cells
  3. B cells that are not able to reach a primary follicle appear to die after several days
31
Q

What comprises MALT? (7)

A

surfaces lined by mucus-secreting epithelium

  1. the gastrointestinal tract
  2. upper and lower respiratory tract
  3. the urogenital tract
  4. conjunctivae
  5. lachrymal glands of the eye,
  6. the salivary glands, 7. lactating breast
32
Q

_______have the structure of lymphoid follicles with parafollicular regions & germinal centers

A

Peter’s Patches

However they are not encapsulated & have lymph & blood-independent entry of antigen from the lumen

33
Q

What is the main function of M cells?

A

transcellular transport of various substances from the:
lumen of the intestine across the epithelial barrier to underlying antigen-presenting cells

-Antigen may also be sampled by lamina propria dendritic cells

34
Q

What is the most abundant immunoglobulin n MALT tissue?

What secretes this?

What is the exception?

A

IgA

-secreted by plasmablast which circulate back to the mucosal tissue after activation (exception: genitourinary = IgG

Immunology (26 decks)

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