Inflammatory Cells

Question 1

What are 5 acute inflammation effector cells?

Answer 1

• vascular endothelial cells
• neutrophils
• mast cells/basophils
• eosinophils
• monocytes/macrophages

Question 2

Vascular endothelial cells

Answer 2

Inflammation

• contraction
• release of chemical mediators (NO)
• expression of adhesion molecules and receptors

Question 3

Leukocytes

Answer 3

• neutrophils
• eosinophil
• basophil/mast cell
• monocyte/macrophage
• lymphocyte/plasma cell

Question 4

What is the avian equivalent of a neutrophil?

Answer 4

Heterophil

Question 5

Neutrophil cell characteristics

Answer 5

Segmented nucleus, multiple complex granules

• recruited by IL-8!!
• short lived –> 24 hrs in circulation, 1-2 days in tissue
• aka: polymorphonuclear leukocytes

Question 6

Neutrophil function

Answer 6

Innate immunity to bacteria and fungi

• phagocytosis
• release of granular contents

Question 7

What are the 3 phases of neutrophil phagocytosis?

Answer 7

• attachment to particles to the cell surface
• ingestion of particles
• breakdown of particles

Question 8

_______ greatly facilitates phagocytosis

Answer 8

Opsonization

- via IgG antibodies and complement

Question 9

Neutrophil granules

Answer 9

• myeloperoxidase: converts H2O to hypochlorous acid which is toxic to microbes
• lysozyme
• antimicrobial substances
• gelatinase: break dwon tissue

Question 10

Enzymes released cause _____ of the exudate and accumulation of pus

Answer 10

Liquefaction
- **reptiles and birds have reduced concentration of enzymes and cannot liquefy the exudate, leading to formation of caseous material

Question 11

Neutrophil extracellular traps

Answer 11

Extracellular fibrillary networks that provide high concentrations of antimicrobial substances

• trap microbes to prevent spread
• meshwork of nuclear chromatin that binds and concentrates antimicrobial peptides and enzymes

Question 12

Neutrophil production and maturation takes place in the _______

Answer 12

Bone marrow
- cytokines stimulate endothelial cells and fibroblasts to produce colony stimulating factors —> CSFs act directly on hematopoietic subpopulations in bone marrow to increase cellular proliferation/differentiation –> release from bone marrow is orderly and age-related with mature segmented cells released first

Question 13

Eosinophils

Answer 13

1-5% of WBCs

• short lived –> 12 hrs in circulation, 1 week in tissue
• emigrate from blood and live in subepithelial sites in skin, lung, GIT, and endometrium
• enter lesions during transition from acute to chronic inflammation!!!

Question 14

What attracts eosinophils?

Answer 14

Histamine, eosinophil chemoattractant factor A (mast cells), eotaxin

Question 15

Eosinophil function

Answer 15

• innate immunity to parasites
• associated with allergies to hypersensitivity
• modulate local immune responses = production and release of cytokines

Question 16

Eosinophil cell characteristics

Answer 16

• bilobed nucleus
• cytoplasmic granules
• major basic protein, lysosomal enzymes and peroxidases (less effective than neutrophils)
• result in major tissue damage (collagenolysis)

Question 17

Eosinophilic exudate

Answer 17

Chronic

- green tinge to muscle

Question 18

Mast cells/basophils

Answer 18

Found in all supporting tissues

• distributed in skin, GIT, and blood vessels (rapid response)
• long lived (4-12 weeks)
• replicate in tissue!!
• deeply basophilic granules and condensed nucleus

Question 19

Metachromatic granules of mast cells

Answer 19

• histamine
• eosinophil chemotactic factor
• heparin
• synthesize prostaglandins, leukotrienes and PAF
• proteolytic enzymes (tryptase)

Question 20

Mast cells express high affinity receptors for ______ on suface

Answer 20

IgE

• stimulated by cross linking of IgE
• fusion of cytoplasmic granules which then fuse with the plasma membrane and exit thru a pore
• immune system must be primed!!!

Question 21

Immediate response of mast cell degranulation

Answer 21

• vasodilation
• vascular leakage
• smooth muscle spasm

Question 22

Late phase reaction of mast cell degranulation

Answer 22

• leukocyte infiltration
• epithelial damage
• bronchospasm

Question 23

Monocytes and macrophages

Answer 23

Originate in bone marrow, migrate in blood for 6 days and settle in tissues as macrophages

• monocytes are short lived in circulation
• macrophages are long lived in tissues, retain ability to proliferate

Question 24

Monocyte/macrophage function

Answer 24

• phagocytosis
• antigen presentation
• immune modulation

Question 25

Monocyte cell characteristics

Answer 25

Large nucleus with indentation, multiple granules and vacuoles - granules are similar to primary neutrophilic granules

Question 26

What are the 2 types of macrophages?

Answer 26

- those that reside within a specific tissue (physiologic) | - those derived from monocytes in response to a stimulus

Question 27

Tissue macrophages

Answer 27

- kupffer cells (liver) - microglia (CNS) - alveolar macrophages (lung) - langerhans cells (skin) - osteoclasts (bone)

Question 28

Macrophages recruited to inflammation

Answer 28

Respond by chemotaxis - arrive as a second wave after neutrophils (12-48 hrs) take over - antigen processing and presentation - engulf and destroy tissue debris and foreign material (less efficient than neutrophils) - modulate immune response via release of cytokines!!

Question 29

How do macrophages destroy tissue and foreign material?

Answer 29

- release of lysosomal enzymes - free radicals - opsonization enhances phagocytosis

Question 30

______ are one of the main triggers of the adaptive immune response

Answer 30

Macrophages

Question 31

Platelets

Answer 31

Biconvex discs - arise from megakaryocyte fragmentation in marrow - hemostasis control - deliver inflammatory mediators to injured sites - preformed substances in granules (histamine) - chemokines involved in chemotaxis (platelet activating factor) - thromboxane A2 (vasoconstriction) - growth factors