Histo - Lymphoid Flashcards

(35 cards)

1
Q

What are the 4 types of Immunity?

A
  1. Cell-mediated (adaptive)
    • Mostly T lymphocytes
  2. Humoral (adaptive)
    • B-lymphocytes & Plasma Cells
  3. Innate (not adaptive)
    • Macrophages, granulocytes, & natural killer cells
    • Epithelia & complement system
  4. Passive Immunity
    • maternal antibodies
      • from placenta & milk
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2
Q

What are the 2 types of Lymphoid Organs?

A
  1. Primary
    • Bone marrow
      • B & T cells formed here
      • B cells mature here
    • Thymus
      • T cells mature here
  2. Secondary
    • Lymph nodes
    • Spleen
    • Diffuse lymphoid tissue of mucosa of GI
      • Tonsils
      • Peyer’s Patches
      • Appendix
    • Mucosa-associated lymphoid tissue (MALT)
      • GI
      • Respiratory
      • Urinary
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3
Q

How is lymph transported?

A
  • Lymphatic vessels
    • transport interstitial fluid (lymph) to blood
  • Lymphoid organs
    • immune cells within
    • primary & secondary
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4
Q

What are the characteristics of Innate Immunity and 3 associated cells?

A

Basics:

  • Immediate & NON-specifc
  • Physical barriers & Cells

Cells:

  1. Leukocytes (WBCs)
    • Toll-like receptors on leukocytes
    • Granular
      • Basophil, Eosinophil, Neutrophil
    • Agranular
      • Monocyte/Macrophage & NK cells
  2. Mast Cells
  3. Dendritic cells
    • Ag presenting cells

Anti-microbial chemicals:

  • Acids
  • Defensins
  • Lysozymes
  • Complement
  • Interferons
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5
Q

What are the characteristics of Adaptive Immunity and 3 associated cells?

A

Basics:

  • SLOWER than innate response
  • More SPECIFIC than innate response
  • Ability to recognize Antigens
    • cause cell response

Cells:

  1. B-cells
  2. T-cells
  3. Ag presenting cells
    • help B & T cells
    • part of mononuclear phagocyte system

Note:

  • Memory lymphocytes = remember response
    • lead to faster response in future contact w/ Ag
    • basis for vaccine
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6
Q

What are the 2 major structural components in this image?

A
  1. Stroma of Lymphoid Organs
    • CT framework
    • Reticular fibers
  2. Parenchyma of Lympoid Organs
    • Immune cells
    • Functional part of organ
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7
Q

What is this?

A

Reticular Fibers

  • Part of Stroma of Lymphoid Organs
  • Stain w/ Silver
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8
Q

What is this?

A

Immune Cells

  • Part of Parenchyma of Lymphoid Organs
    • ONLY immune cells visible
    • Functional part of organ

Note:

  • No stained reticular fibers in this image
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9
Q

What are the 3 types of Lymphocytes?

A

Adaptive Immunity:

  1. T-lymphocytes
    • Helper T, cytotoxic T, Regulatory/Suppresor T, Memory T
    • Mature in Thymus –> Secondary lymphoid organs
  2. B-lymphocytes
    • Plasma cells & Memory B cells
    • Mature in Bone Marrow –> Secondary lymphoid organs

Innate Immunity:

  1. Natural Killer (NK) cells

NOTE:

  • All derive from Lymphoblast in Bone Marrow
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10
Q

What is this?

A

T Lymphocytes

  • Found a_bundantly in GI tract_
    • ​basophilic & round nuclei
  • Cannot quite distinguish from B cells
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11
Q

What is DiGeorge Syndrome?

A

Basics:

  • Thymic aplasia = messed up thymus
  • NO T cells
    • ​no cell-mediated response to Ags
  • ONLY B cells

Treatment:

  • Thymic transplant = ideal option
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12
Q

What is Agammaglobulinemia & Hypogammaglobulinemia?

A

Agammaglobulinemia:

  • NO B cells
    • no plasma cells & no Abs
  • ONLY T cells
    • cell-mediated response

Hypogammaglobulinemia

  • SOME B cells
    • Reduced Ab production
  • T cells present
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13
Q

What is Severe combined immunodeficiency disease (SCID)?

A

Basics:

  • AKA: Adenosine Deaminase Deficiency or Bubble Boy Disease
  • NO T cell & NO B cells
  • Innate Immunity ONLY
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14
Q

What is the different between the 2 types of Lymphoid organs?

A
  • Primary
    • Initial location of maturing lymphocytes
      1. Bone Marrow
      2. Thymus
  • Secondary
    • Where immune response happens
      1. Tonsils
      2. Peyer’s Patches
      3. Veriform Appendix
      4. Lymph nodes
      5. Spleen
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15
Q

What is the difference between images?

A

Thymus of Child (Left) & Thymus of Adult (Right)

Basics of Thymus:

  • Efferent lymphatic drainage ONLY
  • Site of T cell maturation

Structure:

  • Thymic lobes w/ CT capsule
  • Lobes separated by septae
  • Lobules have cortex & medulla

Child vs. Adult:

  • Child = large; Lots of differentiation of T cells
  • Adult = small; Lots of fat & loss of tissue
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16
Q

What are the 2 major structures in this image?

A

Cortex & Medulla of Thymus

Cortex:

  • T-cells = MORE than medulla
    • darker stain
  • Epithelial reticular cells = FEWER than medulla

Medulla

  • T-cells = LESS than cortex
  • Epithelial reticular cells = MORE than cortex
    • _​_lighter stain
  • Hassall’s Corpuscles
    • Wholes of epithelial reticular cells
    • Enlarge w/ age
      • ** helps us ID the thymus**
17
Q

What is this?

A

Medulla of Thymus

  • T-cells
    • small, dark nucleus
  • Reticular epithelial cells
    • larger, more clear/eosinophilic
  • Hassalls Corpuscles
    • LARGEST, most eosinophilic;
    • nuclei similar to reticular epitheial cells
18
Q

What is the Blood-Thymus Barrier?

A

Basics:

  • Dual Basal Lamina
    • Reticular epithelial cells
      • linked by desmosomes
    • Endothelial cells
      • continous capillary
  • Macrophages
    • proximity = help to protect dev. T cells

Note:

  • Together, blood-thymus barrier + Macrophages = protect dev. T cells
19
Q

What is this?

A

Cortex of the Thymus

  • Epithelial reticular cells
    • linked by desmosomes
    • larger; clear cells
  • T lymphocytes
    • smaller; basophilic
20
Q

What is this?

A

Medulla of the Thymus

  • Less T cells
    • small, basophilic
  • More reticular epithelial cells
    • larger, clearish, eosinophilic
  • Hassall Corpuscles
    • largest, very eosinophilic
21
Q

Where are Mucosa-Associated Lymphoid Tissue (MALT) located?

A

Mucosa-Associated Lymphoid Tissue (MALT)

​Systems:

  • GI
  • Respiratory
  • Urinary
    • All = open to outside
      • potential sites for pathogen entry

Locations:

  1. Diffuse lymphoid tissue
  2. Lymphoid nodules
  3. Tonsils
  4. Peyer’s Patches
  5. Appendix
22
Q

What is this?

A

Diffuse Lymphoid Tissue in Esophagus

  • Lymphocytes in CT
    • not making a formal structure yet
  • In Lamina Propria
23
Q

What is this?

A

Lymphoid Nodules in Esophagus

2 Parts of Lymphoid Nodules​

  1. Primary
    • Cluster of tightly packed cells
    • Mostly B cells
  2. Secondary
    • Corona (mantle)
      • new lymphocytes
      • darker outer region
    • Germinal center
      • B cell proliferation
      • B cell differentiation
      • May contain T cells & APCs
        • central lighter region
24
Q

What are the 3 types of Tonsils?

A
  1. Pharyngeal tonsils
    • single
    • wall of nasopharynx
    • covered by pseudostratified columnar epithelium
    • NO crypts
      • if inflammed & hypertrophied = “adenoids”
  2. Lingual tonsils
    • base of tongue
    • numerous
    • covered w/ SSNK epithelium
    • SINGLE crypt
  3. Palatine tonsils
    1. paired
    2. in wall of oropharynx
    3. covered by SSNK epithelium
    4. SEVERAL crypts
25
What is this?
**Palastine Tonsil** * paired * wall of oropharynx * SSNK * Several crypts
26
What is this?
**Peyer’s Patches** **Basics:** * In the ileum (GI) * has M cells (microfolds) in epithelium * over lymphnoid nodules **Function:** * M cells hold B & T cells * Allow dendritic cells to present Ags
27
What is this?
**Appendix** **​Basics:** * Off the cecum * Has many lymphoid nodules **Function:** * Site of immune components
28
What is this?
**Lymph Node** **Basics:** * Both afferent & efferent lymphatic drainage **Function:** * Immune surveillance **Structure:** * Capsule & trabeculae * CT * Hilum **Order/Flow:** 1. Subcapsular sinus 2. Corticol (paratrabecular) sinuses 3. Follicular dendritic cells * not bone marrow derived 4. Medullary sinuses/cords
29
What are the 3 regions of the Lymph Node in this image?
1. **Outer cortex** * B cells in lymphoid nodules * Follicular dendritic cells * not bone marrow-derived * trap Ag for presentation 2. **Paracortex** * T cells 3. **Medulla** * Macrophages * B cells * Plasma cells
30
What is this?
**Lymph Node** **Note:** * Palastine tonsils = NO subcap space
31
What is this?
**Medulla of Lymph Node**
32
What is this?
**High Endothelial Venules in Lymph Nodes** **Basics:** * Found in _lymph node paracortex_ * Found in _tonsils_ * Found in _Peyer’s patches_ **Structure:** * _Cuboidal_ endothelial cells * special venule that do _NOT have SS epithelial_ **Function:** * Allow lymphocytes to move easily
33
What is this?
**Spleen** **Basics:** * _Efferent lymphatic drainage_ * NO afferent lymphatics * thymus & lymphnode ONLY * NO cortex & medulla **Function:** * _Fetus_ * formation of RBC & granulocytes * _Adults_ * Destruction of worn out RBCs * Removal of forgein material * B & T cell activation w/ Ag presentation **Structures:** * CT capsule & trabeculae * Hilum * _White Pulp_ * _Red Pulp_ * ​_Marignal Zone_
34
What is this?
**Spleen** * **White Pulp** * Lymphocytes * Macrophages * Plasma Cells * _Central arteries_ * from trabeculae * PALS * T cells * Lymphatic nodules * B cells * **Red Pulp** * cords of Billroth * Venous sinusoids * Splenic cords * **Marginal zone** * _Junction btw white & red pulp_ * _Receiving compartment_ * Macrophages & APCs
35
What is this?
**White Pulp:** PALS & Lymphoid Nodules **Note:** * PALS = periarterial lymphatic sheath