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1. inflammation

2. Learning objectives
• Summarize the beneficial and harmful effects of inflammation
• Define chronic inflammation and determine its causes
• Identify the nature and origin of cells in acute and chronic inflammation
• Determine cells of chronic inflammation
• Describe components of chronic inflammation
• Define granuloma
• Explain pathogenesis of granuloma

3. Effects of acute inflammation

4. Beneficial effects
1. Dilution of toxins: by inflammatory exudate and allow them to be carried by lymphatics
2. Entry of antibodies: ↑ vascular permeability allow entrance of Abs to extracellular
space
 Ab + Ag complement activation
C5-9 C3b
 Neutralization of toxins

5. 3. Delivery of nutrients and oxygen
4. Drug transport
5. Fibrin formation:
Impede the movement of micro-organisms
trap them then enhance phagocytosis
6. Stimulation of immune response
Drainage of inflammatory exudate allow particulate and soluble Ags to reach
LNs thus stimulate immune response
7. Prepares tissue for repair

6. Harmful effects of inflammation
1. Digestion of normal tissues
Collagenases and proteases may digest normal tissue leading to their
destruction especially BV vascular damage e.g. glomerulonephritis
2. Swelling
May be harmful specially in certain sites as
Epiglottis airway obstruction especially in children death
Cranial cavity ↑ intra-cranial pressure

7. 3. Inappropriate inflammatory response
Allergic inflammatory response may be life threatening as type I
hypersensitivity reaction (anaphylactic shock)
4.Stasis and thrombosis may lead to extensive tissue damage
5. Pain may restrict joint movement leading to muscle atrophy

8. • 6. large exudation e.g. in the pericarduim may disturb cardiac function
• 7. release of lytic enzymes from dead cells may extend tissue damage

9. Chronic inflammation
• Definition: an inflammation of prolonged duration in which
Proceeding simultaneously

10. • 1. Chronic inflammation following acute inflammation
• When the tissue destruction is extensive, or the bacteria survive and persist in small
numbers at the site of acute inflammation
• e.g. in osteomyelitis, pneumonia terminating in lung abscess.
• 2. Recurrent attacks of acute inflammation
• When repeated bouts of acute inflammation culminate in chronicity of the process
e.g. in recurrent urinary tract infection leading to chronic pyelonephritis, repeated
acute infection of gallbladder leading to chronic cholecystitis.

11. 3-De novo:
 Intracellular microbes which are of low toxicity but evoke immunological
reaction; e.g. T.B bacilli and some viruses
 Immune reaction particularly auto-immune diseases
 Prolonged exposure to non-degradable but potentially toxic substances;
e.g. silica, asbestos

12. GENERAL FEATURES OF CHRONIC
INFLAMMATION
• MONONUCLEAR CELL INFILTRATION Chronic inflammatory lesions are
infiltrated by mononuclear inflammatory cells like phagocytes and lymphoid cells.
• TISSUE DESTRUCTION OR NECROSIS Tissue destruction and necrosis are
central features of most forms of chronic inflammatory lesions
• PROLIFERATIVE CHANGES As a result of necrosis, proliferation of small
blood vessels and fibroblasts is stimulated resulting in formation of inflammatory
granulation tissue. Eventually, healing by fibrosis and collagen laying takes place.

15. SYSTEMIC EFFECTS OF CHRONIC
INFLAMMATION
• Fever Invariably there is mild fever, often with loss of weight and weakness.
• Anaemia chronic inflammation is accompanied by anaemia of varying degree.
• Leucocytosis As in acute inflammation, chronic inflammation also has leucocytosis
but generally there is relative lymphocytosis in these cases.
• ESR ESR is elevated in all cases of chronic inflammation.
• Amyloidosis Long-term cases of chronic suppurative inflammation may develop
secondary systemic (AA) amyloidosis

16. TYPES OF CHRONIC
INFLAMMATION
• Chronic non-specific inflammation When the irritant substance produces
a non-specific chronic inflammatory reaction with formation of granulation
tissue and healing by fibrosis, it is called chronic non-specific inflammation
e.g. chronic osteomyelitis
• Chronic granulomatous inflammation In this, the injurious agent causes
a characteristic histologic tissue response by formation of granulomas e.g.
tuberculosis, leprosy, syphilis, actinomycosis, sarcoidosis

17. Granulomatous inflammation
• Granuloma is defined as a circumscribed, tiny lesion, about 1 mm in diameter,
composed predominantly of collection of modified macrophages called
epithelioid cells, and rimmed at the periphery by lymphoid cells. The word
‘granuloma’ is derived from granule meaning circumscribed granule-like lesion,
and -oma which is a suffix commonly used for true tumours but here it
indicates a localised inflammatory mass or collection of macrophages.

19. Pathogenesis of a granuloma
• Formation of a granuloma involves engulfment of the invading agent by the
macrophages, failure to degrade the antigen, morphologic change of
macrophages to epithelioid cells, and incoming CD4+ T cells which
elaborate various cytokines which contribute to proliferation and activation
of cells.

21. Components of a granuloma

23. Differences between acute and chronic inflammation
ChronicAcute
Long (weeks –
months)
Short (days)1. Duration
insidiousacute2. Onset
specificNon-specific3. Specificity
Lymphocytes,
macrophages,
plasma cells
and fibroblasts
Neutrophils
macrophages
4. Cells

24. ChronicAcute
angiogenesisVasodilatation,
↑ vascular
permeability
5. Vascular
changes
--+++6. Exudation
and edema
--+++7. Cardinal
signs
Usually +veUsually -ve
except in
suppurative
inflammation
8. Tissue
necrosis

25. ChronicAcute
+veUsually -ve9. Fibrosis
Low-grade
fever
Weight loss
anemia
High fever10. Systemic
manifestations
Frequently
none
Variable
leukocyte
changes
↑ neutrophils
Lymphocytosis
in viral
infection
11. Changes
in peripheral
blood