Chapter 13 Flashcards
HSC differentiate into what?
- Myeloid-derived cells
- Lymphoid-derived cells
Myeloid-derived cells
(MMEG)
- Monocytes (=> MO and DC)
- Megakaryocytes (=> platelets)
- Erythrocytes
- Granulocytes
Lymphoid – derived cells
- Lymphocytes (T-cells, B-cells, plasma cells)
- NK cells
Describe development of HSC and blood cells
(Young Liver Synthesizes Blood: Yolk sac, liver, spleen, BM)
-
3rd week of development:
- Shortly in yolk sac, then definitively in mesoderm of intraembryonic aorta/gonads/mesonephros region
-
3rd month of embryogenesis:
- Migrate to liver
- Liver = main site of BC formation until shortly before birth.
- Migrate to liver
-
4th month of embryogenesis:
- Migrate to bone marrow
-
By birth:
- BM in ENTIRE skeleton = haematopoietically active
- Liver hematopoiesis ↓ ↓ ↓
-
After puberty:
- ONLY BM in AXIAL skeleton = haematopoietically active
- BM biopsies in adults are taken from PSIS.
- ONLY BM in AXIAL skeleton = haematopoietically active
Leukoerythroblastosis
processes that distort architecture of BM (cancer, granulomatous disese) è release of immature precursors into blood. Results in:
- Left-shift: increase release of immature neutrophil precursor cells into the blood
- MCC = bacterial Infection
- Example: Acute inflammation may cause a increase in neutrophils in bloo
2. Leukoerythroblastic reaction: left shift that in involves the release of immature RBC. Cause =
- Physiologic cause seen in anemia
- Response of bone marrow to fibrosis or a tumor taking up space
NOTE: [IMP]
- cytosis = _____ ↑↑↑ in cell line
- Example = _____
- emia = _____ ↑↑↑ in cell line
- Example = ______
NOTE: [IMP]
- cytosis = reactive ↑↑↑ in cell line
- Example = Lymphocytosis
- emia = neoplastic ↑↑↑ in cell line
- Example = Leukemia
NL adults =____ fat: hematopoietic element ratio
1:1
__________ states = ↓ ↓ ↓ # of fat cells
__________ states = ↑↑↑ # of fat cells
Granulocytes
- Neutrophil
- Basophil
- Eosinophil
- Mast cell
*80% of lymphocytes in peripheral blood are what?
T-cells
What is Leukmoid reaction?
Leukocytosis d/t reactive states (inflammation/stress) causes an
- ↑↑↑ release of immature granulocytes/neutrophils =>
- ↑↑↑ LAP (leukocyte alkaline phosphatase
Leukmoid reaction mimics ______.
Myeloid leukemia
Leukemia = ____ LAP
Leukemia = NL LAP
- Neutropenia = _____ cells/mm3
- Agranulocytosis = _____ cells/mm3
- Neutropenia = < 1500 cells/mm3
- Agranulocytosis = < 500 cells/mm3
Causes of neutropenia
Neutropenia is caused by:
1. Inadequate or ineffective granulopoiesis (4 mechanisms):
- Suppress HSCs (Ex: Aplastic anemia, infiltrative marrow disorders); Patient will also [granulocytopenia + anemia + thrombocytopenia)
- Suppress committed granulocytic precursors due to drugs ***
- Diseases that cause ineffective hematopoiesis (Ex: Megaloblastic anemia, Myelodysplastic syndromes)
- Congenital conditions that cause defects that impair differentiation of granulocytes (Kostmann Syndrome)
2. Rapid destruction or sequestration of neutrophils in periphery
- Immunologically mediated (AI disorder or drugs)
- Splenomegaly: Large spleen causes sequestration of neutrophils and modest neutropenia. Pts will have [neutropenia + anemia + thrombocytopenia]
- Increased peripheral utilization (bacterial/fungal/rickettsial infection)
Suppression of HSC will cause what symptoms?
[granulocytopenia + anemia + thrombocytopenia]
Presentation of neutropenia
- Fever
- Malaise
- Chills
- Weakness and fatigue
Histology of neutropenia
Hypocellularity OR hypercellularity in BM
- Hypo = agents that suppres/destroy granulocytic precursors
- Hyper = excessive destruction of cells in periphery or neutropenia that cause ineffective granulopoiesis = megaloblastic anemia and myelodysplastic)
MCC of agranulocytosis
Drug toxicity
Complications of agranulocytosis
↑↑↑ susceptibility to:
- Bacterial infections
- Fungal infections (Candida and Aspergillus)
Presentation of agranulocytosis
- ^ same sx^
- Death in hours - days
- If patient develops infection: Ulcerating necrotizing lesions in the oral cavity (gingiva, floor of mouth, buccal mucosa, pharynx)
Lymphopenia = _____ (adults)
Lymphopenia = _____ (children)
- Lymphopenia = < 1500 (adults)
- Lymphopenia = < 3000 (children)
What is the process of neutrophil migration that occurs in Neutrophila (Neutrophilic Leukocytosis)?
MO release IL1 (endogenous pyrogen = fever) & TNF-a => ↑↑↑ synthesis of endothelial adhesion molecules (allow neutrophils to NTR). Neutrophil exit BS => tissue via 4 steps
Rolling
- ↑↑↑ in E/P selectin on endothelial cells
- Selectin ligand on PMNs bind to E/P selectins
Crawling (tight binding):
- LPS or C5a stimulate expression of integrin on PMNs
- Integrin binds to ICAM on endothelium
Transmigration
- Neutrophils bind PECAM-1 between endothelial cells
Migration to site via C5a and IL8
↓↓↓ CD16 and Fc receptors
Eosinophilic Leukocytosis (Eosinophilia) is due to?
- Allergic reaction (Type 1 Hypersensitivity reaction)
- Parasite infections
- Hodgkin’s/Non-Hodgkin’s Lymphoma
- Drug reactions
Pathogenesis of INC eosinophils
Th2 => ↑↑↑ IL-5 => ↑↑↑ IgE => ↑↑↑ eosinophils
Basophilic Leukocytosis (Basophilia) is due to
Rare, except in Myeloproliferative diseases (CML = Chronic Myeloid Leukemia)
Pathogenesis of Basophilia
Basophils are located in blood stream.
- Bind to Fc portion of IgE Ab.
- IgE molecules crosslink => degranulation
- Release of histamine (vasodilation) and enzymes (peroxidases and hydrolases)
Monocytosis (INC in MO) is due to?
- Chronic bacterial infections (TB)
- Bacterial endocarditis
- Malaria
- Protozoa infections
- AI: SLE
- IBD
MO/DC are made in ________, as _______.
How do they develop?
- MO/DC are produced in bone marrow as monocytes.
- 3 days later, monocytes NTR tissue => become MO or DC.
- Name depends on which tissue they’re located
- MO in liver => ______ cells
- MO in brain => ______ cells
- MO in bone => _______
- MO in liver => Kupfer cells
- MO in brain => Microglial cells
- MO in bone => Osteoclasts
Functions of monocytes
- Phagocytosis
- Makes cytokine (Key = IL-1 and TNF-a)
- Present antigens
Lymphocytosis often accompanies _______.
Why does it occur?
monocytosis
- Chronic infections (TB)
- Viral infections (HepA, CMV, EBV)
- B. Pertussis
Primary lymphoid organs = _____________
- Sites: ________
Secondary lymphoid organs = ______________
- Sites: ______________
Primary lymphoid organs = where lymphocytes are formed
- Sites: BM and thymus
Secondary lymphoid organs = where mature lymphocytes proliferate
- Sites: LN, spleen, Peyer’s patches and tonsils
Describe layers of LN
-
Cortex, which contains follicles (site of B-cell activation)
* NL germinal centers contain centroblasts (dark on histology) and centrocytes (light on histology) - Paracortex, which contains T-cells activated by APC and high endothelial venules (vessels that let B/T cells NTR node)
- Engorged in immune response
- DiGeorge syndrome = deficiency in T-cells that causes underdeveloped paracortex
- Medulla, made up of cavities/sinuses and cords
- Medullary sinuses/cavities = contain MO = filter lymph and cause phagocytosis
- Medullary cords = tissues between cavities that contain plasma secreting AB.
How are lymphocytes in LN activated to help fight infections?
- Lymph drains from site of infection.
- In lymph, DC picks up antigen via MHC Class I/II and B7.
- Lymph NTRs nodes and moves through: cortex => paracortex => medulla.
- APC (DC) presents antigen to lymphocytes
- LN Cortex:
- What happens? Activation of B-cells
- How: APC stimulates primary follicles (inactive follicles that contain follicular DCs and quiet B cells) => enlarge => become secondary follicles/ germinal centers (where B cells grow and differentiate, make AB, undergo class switching) => B-cells are activated
- LN Paracortex:
- What happens? Activation of T-cells
- Medulla:
- LN Cortex:
What is a lab result to help us differentiate a reactive WBC proliferation (infection) vs. WBC neoplasm?
LAP (leukocyte alkaline phosphatase)
- HIGH in reactive states
- NL in neoplasms
Difference in LN morphology in Acute vs. Chronic Nonspecific Lymphadenitis
- Acute = enlarged and TENDER
- Chronic = NON-tender
Histology in Acute Nonspecific Lymphadenitis
- Large, reactive germinal centers with many mitotic figures
- Hyperplasia of endothelial cells that line sinuses
- Less severe infections = neutrophils in lymphoid sinuses
- Severe infections = entire LN can become necrotic/bag of pus
Types and Causes of Chronic Nonspecific Lymphadenitis
1. Follicular hyperplasia
- MOA = activation of humoral immune response (B-cells)
- Causes = RA, toxoplasmosis, early HIV, B-cell responses
2. Paracortical Hyperplasia
- MOA = stimulation of T-cells
- Causes = Acute viral infections (like EBV)
3. Sinus histiocytes (reticular hyperplasia)
- Non-specific finding, but MC in breast carcinoma.
- Does NOT mean metastatic cancer, LN are just reacting to cancer.
Histology in Chronic Nonspecific Lymphadenitis
- No acute inflammation
- No tissue damage
Histology of Follicular Hyperplasia
- Large germinal centers, surrounded by a collar of small, resting naïve B-cells (mantle zone)
- Tingible-body MO = contain nuclear debris of B cells that undergo apoptosis if they cannot make a Ab with high affinity for antigen
How can we tell if a process is follicular hyperplasia or follicular lymphoma (neoplastic process)? In reactive LAD,
- LN architecture is preserved: recognizable light (-cyte) and dark (-blast) zones
- Size and shape of LN vary
- Tingible-body MO
- – BCL2 staining
Histology of Paracortical Hyperplasia
- Immunoblasts (3-4x size of resting and dark staining): activated T-cells
- Expansion of T-cell zones (containing immunoblasts), that can encroach on follicles
Hemophagocytic Lymphohistiocytosis (MO activating syndrome) is triggered by?
EBV infection
Acute Myeloid Leukemia
Malignant proliferation of myeloblasts in BM => released into blood suppress NL hematopoeisis
Disorders where myeloid progenitors don’t mature correctly => ineffective hematopoeisis => thrombocytopenias
Myelodysplastic Syndromes (MDS)
More severe than proliferative
Myeloproliferative Disease (MPDs)
Proliferation of 1 or more terminally differentiated myeloid elements => IC peripheral blood counts.
Types:
Types of Myeloproliferative Diseases
- CML (Chronic Myeloid Leukemia): ↑ Granulocytes
- Polycythemia Vera:↑ RBC
- Essential Thrombocytopenia: ↑ Megakaryocytes/platelets
- Primary Myelofibrosis
What factors influence WBC neoplasia?
- Chromosomal translocations and other acquired mutations: majority of WBC neoplasms have non-random chromosomal ABNLties
- Inherited genetic factors
- Viruses
- Chronic inflammation
- Iatrogenic (chemo)
- Smoking
HTLV-1 =>
Adult T-cell leukemia/lymphoma
EBV =>
Infects B-cells in the CTX, causing paracortical hyperplasia of T-cells
KSHV/HHV8 =>
B-cell Lymphoma that presents as a malignant effusion in the pleural cavity
HIV => ___
B-cell Lymphoma
Smoking is a RF for what?
AML
______ IN PERIPHERAL BLOOD = ALWAYS ABNL
-BLASTS
Lymphoid neoplasms can present as what?
Leukemias or lymphomas, depending on where they originate.
- Lymphoma = tumor that originates in a lymphoid organ (LN, spleen, etc) OUTSIDE the bone marrow.
- Leukemia = originates in BM, often leaking into the peripheral blood.
Common presentation of Lymphoma
- Present as a mass
- Mostly enlarged, PAINLESS LN (2/3 of NH-lymphoma and all Hodgkins lymphoma)
- 1/3 of NH-lymphoma = symptoms depending on which tissue/organ is involved
- B-symptoms (cytokines cause systemic symptoms: fevers, chills, night sweats)
Types of lymphomas
- NHL
- Hodgkin’s Lymphoma
- Plasma cell neoplasias = Most commonly Multiple Myeloma – lytic lesions of bone/secretion of light chains or entire Ig
How do Leukemias usually present?
Presentation due to BM suppression (tumor cells suppress NL hematopoiesis)
- Infection (neutropenia)
- Bleeding (thrombocytopenia)
- Anemia
Rules for lymphoid neoplasms
- Histology needed to dx
- Daughter cells are all monoclonal
- Most are B-cell origin (85-90%), even though T-cells are 80% of lymphocytes
- Cause immunological dusfunction: assx with immune ABNL and may express mutated Ig
- Neoplastic B and T-cells circulate widely, but tend to home to and grow in areas where NL counterparts reside
- Differentiation of neoplastic WBC is NOT useful for diagnosis or determine the prognosis.
- Staging ONLY useful for Hodgkin’s lymphoma.
Why is staging ONLY useful for Hodgekins lymphoma
- HL = spreads in orderly fashion.
- NHL = spreads widely and unpredictably