Histology #5 (Immunology) Flashcards
Primary Lymphoid Organs
- Thymus
- Bone marrow
BOTH - central loactions for blood and immune cell development
Bone Marrow
Red or Yellow Bone marrow - located in the cavity /center of most bones
Red marrow - blood stem cells
Yellow marrow -Stem cells that become bone acartdge or fat
Bone marrow vasculature composed of arterioles which transition into a dense network of fenestrated sinsusoids
- Have smooth porus bone + have areas with large gaps –> help move things
- Have perivascilar reticular cells + fibroblasts - aid in blood cell development
Function of Bone Marrow
Thymus and bone marrow = central points for lymphocyte development
Bone marrow - produces RBCs, + White blood Cells + Platlets
- IN sinusuidal space you have progenitor cells –> cells ca become lymphoctes + WBCs + RBCs –> go to blood –> go to body
Bone marrow Histology
Have Trobecular at the top –> then granulocytes (mature WBCs) –> Then megakaryocytes (elongated and round ; makes platlets) –> Then erthyorid island (makes RBCs)
Thymus Gland
Location - Suprior mediastinual retrostinial (Above the heart)
Thymus = split into two lobes with a cortex and medula
Layers of the Thymus
Outter = capsle - invaginates into the interlobal septum
- Has blood vessles + lymphatics + nerves
Cortext = has ympahtics and cortocal eithelial
Medulla - has medula epithiliary and DCs + has thymic cropsucle
- Helps with regeneration of the thymis
Interlobular space - has bu,py texture
Function of Thymus
Function - Development of T cells
Progentitor cells form bone marrow will enter thymic medulla by high endothelial venules (HEVs) –> get T cel development
T cell development - need binding to APC with good affinity for a positive signal ; self-reactive leads to negative sleective which causes apoptosis
Thymus Histology
Left - Fetal - high cell density (thick medual and cortical spaces + lots of squamous cels)
Right - Adult - Low density of cells + corpuscles are large
- Shows thymus shrinks as we age
Secondary Lymphoid Organs
Function - Secondary Lymphoid organs are where the lymphociytes are activated and do their jobs to fight pathogens
Organs:
1. Lymph Nodes (Encapsulated)
2. Spleen (Encapsulated)
3. Mucocal associated (Tonsils) + Peyer’s Patches + Bronchus-associated lymphoid tissues)
Arranges as a series of filters
Lymph Nodes
Encapsulated clumps of tissue (bean shaped)
- Encapsuladed by a dense college tossie + have trebecula
Contain Immune cells
Function - Filters debris and antigens + immune response
- imune cells trap pathogens and starts producton of AB
100-200 nodes throughout the body
Swoellen or painful lymph nodes = sign of active immune system
Layers of the Lymph Node
Layers of the Lymph nodes:
1. Corext - has B cells
2. Paracorext - has T cells
3. Medual (innermost) - has B and T cells
Vessels = branch to tissues around the body –> bring lymph to lymph nodes through afferebt vessles (leave and through efferent ; come in through afferent
Lymph Node histology
Outter layer = capsul –> Then have cortext and Paracorext
See germinal center - trasient stucture where Mature B cels will activate + proliferate + difefrentiate
Spleen
Largest Lyphoid organ
Encapsulated - trabeculae around spleen
Only lymph organ not supplied by lymphatic vessels
Location - Upper left abdomen beneath the diaphram
Compoased of two types of tissues - Red + white pulp
Function:
1. Filter for blood
2. Break down aged RBCs
3. Stores and breaks down platets
Red vs. White pulp
Red Pulp - Vacular Sinses filled with blood ; filters foreign sbstantes or damaged RBCs
White Pulp - Lymphatic tissue ; functions in immune resonse
Spleen Histology
See Red and White pulp + see srunded by capsul
Mucousa-Asscoiated lymphoid tissue (MALT)
Overall - Dispersed aggregates of nonencapsulated lymphoid tissue within mucosa
Funcation - Local immune response at the mucosal surface
Types:
1. Gut associated lymphoid tissue (GALT)
2. Bronchus associated lymphoid tissue (BALT) - immune response in lung
3. Nasal-asscoiated lymphoid tissue (NALT) - immune response in nose (Ex. Tonsils)
Peyer’s Patches
Large masses of confluent lymphoid follciles
Location - found in lamina propria and submucosa of ileum (part of small intestine)
Function - Protext against pathogenic bacteria growth in intestine (provides immune response in small intestine)
Peyer’s patch histology
Image - histology of the ilum –> peyers is in teh submucosal area
Bronchus assoaited lymphoid tissues (BALT)
Overall - Intrapulmonary lympoid tissue found in all lobes of the lungs and along the bronchi
Function - maintence and regulation of lung mucosal immune homeostasis (gives immune response in lung mucosa)
- Similar to Peyer’s patch but in lung
Histology - See lymphotic follicle
Ciculatory Vs. Lymphatic system
Ciculatory - Closed system + contains a pump (heart)
Lymphatic system - open system + lined by lymphatic endothelial cells (LECs) that have a different morphology + no pump
How does lymphatic draignage occur
Lymphatic drainage is facilitated by interstitial pressure which is determined by hydrostatic/oncotic equilibrium
Process:
Arterial to venous blood you have gas exhnage in the capilies = fluid going in/out of the capailies AND fluid going into he interstitiom = interstial pressure rises –> interstitial pressure move fluid into lymphatic system
When interstital pressure is graeter than the lymphatic pressure fluid diffises into the INTITIAL lymphatics
- Movement into intial lymphatics is facilitated by discontinous basement memebrane on the intial lymphatics (Lymphati enodthlial at begnining of vessle has discontinous basement mambrane which allows for fluid uptake)
ONce interstial pressure increases and flud goes into the lymphatics the fluid goes towards the collecting lymphatics
- Collecting lymphatics posses a continous basememnt memebrane + one way valve and smooth mucle – alows the collecting lymhatics to hold the liquid and prevents the liquid from going back to intial lymphatics
Function of smooth mucle in Collecting lymphatics
Contractinon of the smooth muscle drives fluid upstream/prevents the fluid from going back and creates suction within the pre-colecting lymphatics to get the fluid to go towards the collecting lymphatics
Lymphatic histology
- = Lymphatic vessel
See artery (has thick exterior) and veins which ahve thicker exterior compared to the lymphatic vessels
- If have RBCs in the middle = know it is NOT a lymph vessel
Differentiation of Immune cells
Immune cells = come from hematopeotic stem cells
Immune cells are created through Hematopeosis
Stain Types
- H and E
- Touline Blue stain
- Wrights stain
- IHCs
H and E stain
Stains nulceo purple and cytoplasm/ECM pink
Touline Blue Stain
Metachromtic properties
Stains mast cell granuals
Wrights stain
Mix of Eosin and methylene blue
Nuceli stain purple/blue
Nuertophilic granules stain brown
Eosinophilic granuales stain red
Erthrocytes stain pink
Lymphocytes cytoplsm stains pale blue
IHC
IHC antibody stains either nucleus or cytosplams of a specific cell type
Usually shows up brown but can be other colors
Megakeryocyts
Location - located in bone marrow
Function - Responsble for platlet generation
- Can form thousands of platlets from one cell
- Proplatlets - extenstion of long cytoplasmic porcesses
- Fragmentation into platlets
- Form granuales that have cytokines and surgars that help the platlets function
Mature megakaryocytes = form protoplatlents into blood vessels THEn pitch them off and rform platlets themselves
Megakaryocytes Histology
See larger + multinucleated + cytosol stains blue because of granuals
Platlets (Thrombocytes)
Immune function
Small
Form blood clots and stop bleeding (restors barrier against outside)
Expressing pattern Recignition receptors (PRRs) - bind to pathoges
Cytokine and chemokine release to bring in other immune cells
Histology - Platlets = small disc shap
Thromocytes + macrophages
Platlets (Thrombycotes) can actibate otehr immune cells - activate macrophages + nuetrophils + dendritic cells
Megakeryoctyes + platlet histology
Megakeryocytes
- largest cell in bone marrow
- Granular cytoplasm
- Multi nucelated
- Poplatelet extension
PLatlets
- Small
- Disk shaped (inactivated) or spiky (Activated)
- Anuceluated
- Stain purple/blue on H and E due to granuals
Image - megakeyyocyte with platlet budding off
Mast cell
Function - mediate the inflamatory repsonse
- Associated function with alllergs becase the granuals they contain
Contain granuales loaded with histamine and heprin
- When activated granials are released –> Histamine is release –> histamine causes teh blood vessles to expand/become more pemable –> get allergy response
- Responsible for redness + warmth + swelling often seen in allergic reactions
Mast cell histology
Round or oval shaped
Cytoplasm filled iwth granals
Round/Oval nuceli
Typically found in connective tsisues
Granuals stain purple
Can idetify them using Toluine blue
Mast Cell histology (Touline Blue)
Touline blue stain
- Metachomatic granuals
- Stain granulocytes an intesne purple
- See connective tissue + interaction wih Mast cells
Neutrophil Histology
Image - shows a multi lobal nuceli
Multi lobular nucelus (2 or 3-5)
12-14 um (smaller than eosenphils or macrophages ; large than RBCs)
Cytoplams pale pink in H and E
Stains used:
1. H and E
2. Stains for blood smear (Wright’ stiain)
- Pale blue/pink cytoplams + many granual
3. IHC
Neutrophil Histology (Wright’s stain)
Pale blue/pink cytoplams
Neutrophil Histology (IHC)
For IHC use CD66b and myeoperoxidase (MPO)
Eosenophil Histology
Bilobal Nucelus
Larger than nuertophils ; smaller than macrophages
Acidophilic granials stain red/purple
Stains used:
1. Any stain containing Eosin
2. Congo Red
3. IHC
Eosenophil Histology (Congo red)
Congo Red = Azo dye with pH indicator properties
Image - nuertophils are a dark orange/brown
Eosenophil Histology IHC
IHC markers = AB against secreted factors (Ex. against major basic protein) OR ILR5a or CCR3
Macrophage and Monocyte Histology
Eccentric nuclei (central nucleaus ; indented nucelus)
Round/oval shape
large (10-30 um)
Foamy looking cytoplams (because of seondary lysosome)
Stains:
1. H and E
2. Stains for blood smears (Wrights)
3. IHC markers
Macrophage and Monocyte Histology (Wright stain)
Have pale blue cytoplasm + few granuales
Macrophage and Monocyte Histology IHC
AB = CD68 + Cd11b + CD14
T and B cell histology
T and B cells = similar in side to RBCs + have spheric nuclei + scant cytoplasm
- In H and E it is hard to distigush betwen T and B cel;s
- Key featire = sherical nucleus with scant cytoplasm (dark dot because mostlu nucleus and less cytopslam)
IHC:
- T cells = CD3 + CD4 (for CD4 T cells) + CD8 (for CD8 T cells)
- B Cells = CD19
NK cell histology
Image - Wright’s stain
NK cells = Bigger than T and B cells
Larger nuclei (conatins course chromatin)
Smaller granuales in the cytoplasm (surroudning nuclei)
IHC marker - CD56
Plasma Cell histology
Larger than lympphocytes
Round nucelus with coarse chromatin
- Nuclei = arranged in “clock face/art wehen” pattern + have perinucelus clearing (white/lighter pruple next to the nucleus)
Abundent deep blue cytoplasm
IHC marker = CD138
SCID Histology
CML phases
Chronic –> Associated –> BLAST pahse
CML pathophysiology
BCL-ABL 1 is an oncogene –> leads to constitutivleu active Tyrone Kinase
Result - Granulcytic overproduction
- get extra cells in the blood and bone marrow
Philideplphia chromosme karytoptype
CML Histology #1
See a TON of cells (No white spaces between cels)
CML Histology #2
A - bone marrow Aspirate
B - Bone marrow biopsy
C - Bone marrow biposy
D - Myofibrosis in bone marrow Biopsy
