Acute Inflammation 2

Question 0

Cells of the cellular response

Answer 0

• The cell types involved depend on the nature of the stimulus
• Each cell type is highly specialised to combat the initiating stimulus

Granulocytes (PMNL)
–Neutrophils (bacteria)
–Eosinophils (parasites, allergic stimuli)
–Basophils (allergic responses)

Mononuclear Cells
•Monocytes (blood) & Macrophages (bacteria, fungi, protozoa)
•Giant cells
•Lymphocytes (viruses, bacteria, parasites, allergens)

Platelets (vascular injury, coagulation)

Endothelial cells (chemical mediators)

Question 1

The Cellular Response

Answer 1

•Primary objective is to deliver leukocytes from the blood to the site of infection or injury
•The types of cells vary depending on:
–progression of inflammation (acute or chronic)
–nature of causative agent (trauma, infection (viral, bacterial)
•Initiated by changes in vascular permeability

Question 2

Granulocytes: neutrophils

Answer 2

• First response to bacterial infection
• recruited by chemotactic factors
• activated by phagocytic stimuli
• granulate: release bacteriocidal enzymes and oxygen free radicals

Question 3

Granulocytes: eosinophils

Answer 3

• Parasitic and allergic response
• release mediators from granules
• degranulation releases:
• enzymes
• toxic proteins
• cytokines
• chemokines
• leukotrienes
• motile with some small phagocytic activity

Question 4

Granulocytes: mast cells

Answer 4

-Located in connective tissue around blood vessels
-sensitized by IGe binding to cell surface
Degranulates readily when antigen bonds to cell surface IGe molecules
Granules release vasoactive substances e.g heparin ( prevent thrombosis and blood stasis, histamine and leukotrienes

Question 5

Monocellular cells: macrophages

Answer 5

• derived from blood monocytes
• the major tissue phagocytic cell
• produce pro inflammatory cytokines
• aids some pathogens to escape destruction e.g Trojan horse
• may form to produce multinucleated giant cells in chronic conditions

Question 6

Giant cells

Answer 6

Langhans giant cells
Foreign body giant cells
Touton giant cells

Question 7

Mononuclear cells: monocytes

Answer 7

Circulate through blood and lymph
Circulate in an inactive state and must be activated by an antigen via specific receptors
Can proliferate and adapt
Long lives memory
T- cells ( cell mediated immunity )
B-cells ( antibody mediated or humoral immunity)
Plasma cells

Question 8

CHEMOTAXIS

Answer 8

•At the site of injury, leukocytes undergo directional migration by a process termed chemotaxis:
–in response to gradients of chemoattractants produced at the site of injury:
1.Exogenous chemoattractants
•Bacterial products (peptides, lipids)

2. Endogenous chemoattractants
•Chemokines
•Complement (C5a)
•Cytokines (IL-8)
•Chemical mediators of AI (LTB4)
•ATP

Question 9

Phagocytosis

Answer 9

1. Recognition and attachment
2. Engulfment
3. Killing and degradation

Question 10

Cellular Processes: Activation

Answer 10

Functional responses induced on leukocyte activation

1. Production of arachidonic acid metabolites
2. Degranulation & secretion of lysosomal enzymes; activ. of oxidative burst
3. Secretion of cytokines
4. Modulation of leukocyte adhesion molecules
5. Induction of cell division (lymphocytes)