Histo - Lymphoid Flashcards
What are the 4 types of Immunity?
-
Cell-mediated (adaptive)
- Mostly T lymphocytes
-
Humoral (adaptive)
- B-lymphocytes & Plasma Cells
-
Innate (not adaptive)
- Macrophages, granulocytes, & natural killer cells
- Epithelia & complement system
-
Passive Immunity
- maternal antibodies
- from placenta & milk
- maternal antibodies
What are the 2 types of Lymphoid Organs?
-
Primary
-
Bone marrow
- B & T cells formed here
- B cells mature here
-
Thymus
- T cells mature here
-
Bone marrow
-
Secondary
- Lymph nodes
- Spleen
-
Diffuse lymphoid tissue of mucosa of GI
- Tonsils
- Peyer’s Patches
- Appendix
-
Mucosa-associated lymphoid tissue (MALT)
- GI
- Respiratory
- Urinary
How is lymph transported?
-
Lymphatic vessels
- transport interstitial fluid (lymph) to blood
- Lymphoid organs
- immune cells within
- primary & secondary
What are the characteristics of Innate Immunity and 3 associated cells?
Basics:
- Immediate & NON-specifc
- Physical barriers & Cells
Cells:
-
Leukocytes (WBCs)
- Toll-like receptors on leukocytes
- Granular
- Basophil, Eosinophil, Neutrophil
- Agranular
- Monocyte/Macrophage & NK cells
- Mast Cells
-
Dendritic cells
- Ag presenting cells
Anti-microbial chemicals:
- Acids
- Defensins
- Lysozymes
- Complement
- Interferons
What are the characteristics of Adaptive Immunity and 3 associated cells?
Basics:
- SLOWER than innate response
- More SPECIFIC than innate response
- Ability to recognize Antigens
- cause cell response
Cells:
- B-cells
- T-cells
- 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
What are the 2 major structural components in this image?
-
Stroma of Lymphoid Organs
- CT framework
- Reticular fibers
-
Parenchyma of Lympoid Organs
- Immune cells
- Functional part of organ
What is this?
Reticular Fibers
- Part of Stroma of Lymphoid Organs
- Stain w/ Silver
What is this?
Immune Cells
- Part of Parenchyma of Lymphoid Organs
- ONLY immune cells visible
- Functional part of organ
Note:
- No stained reticular fibers in this image
What are the 3 types of Lymphocytes?
Adaptive Immunity:
-
T-lymphocytes
- Helper T, cytotoxic T, Regulatory/Suppresor T, Memory T
- Mature in Thymus –> Secondary lymphoid organs
-
B-lymphocytes
- Plasma cells & Memory B cells
- Mature in Bone Marrow –> Secondary lymphoid organs
Innate Immunity:
- Natural Killer (NK) cells
NOTE:
- All derive from Lymphoblast in Bone Marrow
What is this?
T Lymphocytes
- Found a_bundantly in GI tract_
- basophilic & round nuclei
- Cannot quite distinguish from B cells
What is DiGeorge Syndrome?
Basics:
- Thymic aplasia = messed up thymus
-
NO T cells
- no cell-mediated response to Ags
- ONLY B cells
Treatment:
- Thymic transplant = ideal option
What is Agammaglobulinemia & Hypogammaglobulinemia?
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
What is Severe combined immunodeficiency disease (SCID)?
Basics:
- AKA: Adenosine Deaminase Deficiency or Bubble Boy Disease
- NO T cell & NO B cells
- Innate Immunity ONLY
What is the different between the 2 types of Lymphoid organs?
-
Primary
-
Initial location of maturing lymphocytes
- Bone Marrow
- Thymus
-
Initial location of maturing lymphocytes
-
Secondary
-
Where immune response happens
- Tonsils
- Peyer’s Patches
- Veriform Appendix
- Lymph nodes
- Spleen
-
Where immune response happens
What is the difference between images?
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
What are the 2 major structures in this image?
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**
What is this?
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
What is this?
Cortex of the Thymus
-
Epithelial reticular cells
- linked by desmosomes
- larger; clear cells
-
T lymphocytes
- smaller; basophilic
What is this?
Medulla of the Thymus
-
Less T cells
- small, basophilic
-
More reticular epithelial cells
- larger, clearish, eosinophilic
-
Hassall Corpuscles
- largest, very eosinophilic
What is this?
Diffuse Lymphoid Tissue in Esophagus
-
Lymphocytes in CT
- not making a formal structure yet
- In Lamina Propria
What is this?
Lymphoid Nodules in Esophagus
2 Parts of Lymphoid Nodules
-
Primary
- Cluster of tightly packed cells
- Mostly B cells
-
Secondary
-
Corona (mantle)
- new lymphocytes
- darker outer region
-
Germinal center
- B cell proliferation
- B cell differentiation
- May contain T cells & APCs
- central lighter region
-
Corona (mantle)
What is this?
Palastine Tonsil
- paired
- wall of oropharynx
- SSNK
- Several crypts
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
What is this?
Appendix
Basics:
- Off the cecum
- Has many lymphoid nodules
Function:
- Site of immune components
What is this?
Lymph Node
Basics:
- Both afferent & efferent lymphatic drainage
Function:
- Immune surveillance
Structure:
- Capsule & trabeculae
- CT
- Hilum
Order/Flow:
- Subcapsular sinus
- Corticol (paratrabecular) sinuses
- Follicular dendritic cells
- not bone marrow derived
- Medullary sinuses/cords
What are the 3 regions of the Lymph Node in this image?
-
Outer cortex
- B cells in lymphoid nodules
- Follicular dendritic cells
- not bone marrow-derived
- trap Ag for presentation
-
Paracortex
- T cells
-
Medulla
- Macrophages
- B cells
- Plasma cells
What is this?
Lymph Node
Note:
- Palastine tonsils = NO subcap space
What is this?
Medulla of Lymph Node
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
What is this?
Spleen
-
White Pulp
- Lymphocytes
- Macrophages
- Plasma Cells
-
Central arteries
- from trabeculae
- PALS
- T cells
- Lymphatic nodules
- B cells
- Lymphocytes
-
Red Pulp
- cords of Billroth
- Venous sinusoids
- Splenic cords
-
Marginal zone
- Junction btw white & red pulp
- Receiving compartment
- Macrophages & APCs
What is this?
White Pulp:
PALS & Lymphoid Nodules
Note:
- PALS = periarterial lymphatic sheath
