Leukocytes Flashcards by Oliver Taylor

Leukocytes are derived from ___________________

A common Hameopoietic Stem Cell

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Haemopoeitic stem cells are _________ and are __________

Pluripotent

Self-renewing

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When HSCs divide one cell becomes ___________________ and the other becomes ____________

Becomes dedicated to a particular lineage

Quiescent

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Lineage commitment is dependent on _________, ________, _________ and ___________________.

Cytokines
Hormones
Epigenetics
Other signally molecules

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Give 3 examples of lineage-commitment specific cytokines

EPO = Erythropoietin commits cells to the erythroid lineage
G-CSF = Commits cells to the granulocyte lineage
TPO = Thrombopoietin commits cells to the Megakaryocyte lineage

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The process of lineage commitment and maturation can be __________ at any point

Disrupted

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Early precursor cells are usually found ___________________ and maturing forms are found ___________________

Adjacent to Trabecular bone

Deeper in the marrow space

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What is the composition of Bone marrow haematopoietic regions?

60% Granulopoiesis
25% Erythropoiesis
15% Lymphocyte

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Neutrophils comprise ___ to ___ of WBC count. They develop from _________ in the _________

40-70%
Myeloblasts
Bone Marrow

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Neutrophils are characterised by:

3-5 nuclear segments
Cytoplasmic granules (Primary and Secondary)
9-15um in diameter

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Primary granules are made during the ___________ stage, an important granule component is ___________________.

Promyelocyte stage

Myeloperoxidase MPO

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Secondary granules are made during the _________ stage

Myelocyte stage

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Neutrophils generally leave the circulation by following ____________ this is called ________. To do this they have to ___________________.

Chemical signals
Chemotaxis
Rearrange their cytoskeleton

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For efficient phagocytosis targets need to be __________ with __________ or ____________. These are recognised by ________________.

Opsonised (Coated)
Immunglobulin (Ig) or Complement protein
Cell-surface receptors

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During phagocytosis temporary __________ called _______ encircle the particle before ingestion

Cell projections

Pseudopods

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What are the 2 pathways used to destroy pathogens?

Fusion with the primary or secondary granules

Generation of reactive oxygen species

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Neutrophils can abnormalities in _________________ or ________________. This may increase the risk of ____________.

Granule development
Intracellular killing
Infection

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Neutrophil Extracellular Traps (NETs) are composed of _________________ studded with __________________. They allow pathogens to be killed ___________, however this results in _________.

Smooth Filaments
Granule components
Extracellularly
NETosis

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What is NETosis?

A unique form of cell death caused by the use of NETs b neutrophils. It is due to the progressive loss of intracellular membranes which causes the cell membrane to rupture.

How are NETs formed and what induces this?

Generated through ejection of intracellular components, it can be induced by:

Infection
Reactive Oxygen Species
Antibodies and Antibody-Antigen Complexes
Activated by platelets

What is Neutrophilia?

Increased Neutrophil count 10-50 x 10^9 per L

There is increased granulation and Dohle bodies and cytoplasmic vacuoles are present
Nucleus lobes maybe also appear as one, “left shift” neutrophils

What causes Neutrophilia?

Infection
Acute Inflammation
Stress
Pregnancy
Trauma
Steroid and cytokines

What is Neutropenia?

Decreased Neutrophil count can be classed as
Mild = 1-1.9 x 10^9 per L
Moderate = 0.5-0.9 x 10^9 per L
Severe =

What is the normal range for Neutrophil count?

2-8 x 10^9 per L

What causes Neutropenia?

- Infection - Drugs/Chemo - Autoimmune disease - Presence of Anti-granulocyte antibodies aka Immune neutropenia - Some Haematological disorders

Eosinophils are characterised by:

- 2-3 nuclear lobes - Granule filled cytoplasm, usually more densely packed than neutrophils - 12-17um in diameter

Eosinophils are _________ at killing bacteria than neutrophils. They bind to ____ and ____ coated _________. They are capable of developing _____ and are also involved in _______________.

``` Slower IgG and C-3 coated Parasites NETs Allergic Reaction ```

Eosinophilia is often caused by _________, __________ and _________________.

Allergies Medication Parasite Infection

Basophils are characterised by:

- 2 nuclear segments - Large round cytoplasmic granules that overlie the nucleus - 12um in diameter

Basophils play a role in ______________ and the response to _________. They have receptors for ___, ___, ___, _________ and __________.

Allergic Reactions Parasites IgG, IgE, C5a, Histamine and Chemokines

Basophils release _________ on activation.

Histamine

Basophilia is very ________. It occurs _________________________.

Rare | Only in malignancies like Chronic Myeloid Leukaemia (CML)

Monocytes are characterised by:

- Horseshoe shaped nucleus - Faint blue-grey cytoplasm - Cytoplasmic Vacuoles - 15-30um in diameter

Monocytes are __________ but they cannot be seen clearly on the microscope. They contain _________, ________, ____ and _________

``` Granular Enzymes Lysozyme MPO Coagulation system proteins ```

Monocytes are able to respond to _________________ in order to move. When they enter the tissues they can form ___________. These cells are capable of _______________ and can release chemicals that can ________ or _________ immune response

``` Chemical Signals Macrophages Antigen Presentation Increase Decrease ```

What is Monocytosis?

An increase in the number of Monocytes

Monocytosis is associated with ________ and ________. Rarely we see persistent Monocytosis, this is usually due to _________________________.

Infection Inflammation Chronic Myelomonocytic Leukaemia

Lymphocytes are characterised by:

- Round and slightly indented nuclei - Mature Chromatin - Scant blue cytoplasm - 7-12 um diameter

Give a brief summary of B-cells:

- Mature in the bone marrow and lymph nodes - 5-25% of the lymphocytes in blood are B-cells - Produce antibodies - Undergo genetic changes to optimise receptor binding

Give a brief summary of T-cells:

- Mature in the thymus - 70-85% of the lymphocytes in the blood are T-cells - They are involved in cell-mediated immunity - Can act as APCs or cytotoxic cells

Give a brief summary of NK cells:

Large Granular Lymphocytes are characterised by:

- Larger size - More voluminous blue cytoplasm - Contain Azurophilic granules

Large Granular Lymphocytes are commonly _____ and occasionally ______

NK cells and occasionally T-cells

Lymphocytosis is an increase in ______________. It is commonly seen in _____________, __________ and __________

Lymphocyte count Viral Infection Seizures Hypoxia

Malignant Lymphocytosis is common in ____________. It can be from the _ or _ cell lineage but is commonly from the _ lineage. It ______ be identified based on morphology

Older people B or T B lineage Cannot

Plasma cells are end stage _____ that can produce _____________. They are ______ found in the blood

B cells Immunoglobulins Rarely

Plasma cells are characterised by:

- Eccentric nucleus - Perinuclear hofs - Intensely basophilic cytoplasm