Leukocyte Structure and Function Flashcards

1
Q

Which cell lineage do Leukocytes originate from?

A

Both myeloid and lymphoid progenitors

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2
Q

Activation of Leukocyte

A

A change in morphology and behavior of a leukocyte resulting from an extracellular signal

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3
Q

CD

Cluster of Differentiation

A

Cell surface markers
Over 350
Enable identification of functional subsets

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4
Q

Myeloid Cell Line

A

First line of defense against pathogens and tissue damage
Include inflammatory cells that regulate inflammatory response
Necessary for development of adaptive immune system

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5
Q

Most abundant leukocyte?

Least abundant leukocyte?

A
Most = neutrophil 55-70%
Least = monocyte 3-8%
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6
Q

Neutrophils

PMNs

A
Characteristic dark and light granules
Multi-lobed nucleus
phagocytotic and activator of bactericidal mechanisms
highly chemotactic
CHIEF CELL of ACUTE INFLAMMATION
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7
Q

PRR

A

Pattern Recognizing Receptors
Found on neutrophils and macrophages
Recognize PAMPs and DAMPs

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8
Q

How do neutrophils kill pathogen?

A

Intracellular killing:
phagocytosis followed by oxidative burst
phagosome fuses with lysosome
phagolysosome creates oxidative burst that creates reactive oxygen species.

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9
Q

Primary Granules of Neutrophils

A

Dark staining
Antimicrobial proteins and compounds
Fuse with endosomes and empty contents
Kill ingested bacteria

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10
Q

Secondary Granules of Neutrophils

A

Pale
Fuse with endosomes and trigger oxidative burst
Release contents EXTRACELLULARLY

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11
Q

Tertiary Granule of Neutrophils

A

Contain gelatinase (MMP-9) that breaks down ECM for migrating neutrophil

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12
Q

Difference between 1, 2, and 3rd granules of neutrophils?

A

Primary granule fuses with the endosome while 2 and 3rd granules are excreted

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13
Q

Oxidative Respiratory Burst

A

Increased O2 consumption
Production of O2 (-)
Production of H2O2 and other bactericidal ROS

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14
Q

Granules Specific to Primary and Secondary Granules

A

Primary: Myeloidperoxidase (MPO) and Sulfated PG

Secondary: Lactoferria, Collagenase, B12 binding protien

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15
Q

Major Enzyme of Oxidative Burst

A

NADPH oxidase
made up of 5 subunits (2 bound to membrane)
Found in secondary granule
Remains cytosolic until it is activated.
Converts O2 to O2(-)
Then superoxide dismutase converts ROS to H2O2

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16
Q

Myeloperoxidase

MPO

A

Only found in primary granule

converts H2O2 to hypochloric acid

17
Q

Catalase

A

Breaks down H2O2 to non-harmful H2O, O2

18
Q

Chronic Granulomatous Disease

A

Mutation in NADPH oxidase
In ability to form O2 (-) from O2
Inhibits oxidative burst

19
Q

Eosinophils

A

Kiling of antibody-coated parasites

Primarily tissue resident cells

20
Q

Basophils

A

(similar to mast cells)
Release granules containing histamine (both mast and basophils)
Circulating cell (mast cells are resident)
Circulate as mature cells
Source of blood histamine

21
Q

Monocytes

A

Enter tissue to become resident macrophages
Patrol circulation for sites of injury/ infection
Both inflammatory (CD14+) and repairative (CD16+)
Biphasic response to infection

22
Q

Macrophage

A

Derived from circulating monocyte
APC cell with phagocytic and bactericidal mechanism
Scavengers, Secretory Cells, Regulators and APCs

23
Q

Difference between macrophages and neutrophils

A

Mac are long lived, self replicating and adaptive with modest metabolic burst

Neuts hour life span, have single function, accumulate quickly then die, strong metabolic burst

24
Q

Where does leukocyte Trafficking occur?

A

Capillary beds

25
Signs of Inflammation
Redness, swelling, heat, pain
26
Control of Inflammation
Cell adhesion molecules (CAMs) and chemokines expressed by ENDOTHELIAL cells and Leukocytes regulate migration into and out of tissues
27
CAM family
Selectin binds to Mucin-Like CAMs (MLC) | Integrins bind to Ig-superfamily CAMs
28
Leukocyte / Neutrophil Trafficking
``` Tethering Rolling Activation Adhesion Diapedesis Transversing Basal lamina Migration through ECM ```
29
Rolling
selectin mediated adhesion weakly adheres leukocyte to endothelial surface causing rolling like motion
30
Activation
Chemokines secreted by endothelium signal through G Protein Coupled receptors Integrins are activated (Inside-Out activation) Binding causes conformational change of integrins
31
Diapedesis
Leukocytes extedns across endothelial junctions and some through the cell. Vascular integrity is maintained via zipper like mechanism