Chronic Inflammation Flashcards
How do we progress from acute to chronic inflammation
If agent causing acute is not removed
How does acute -> chronic happen
Alongside organisation
1. lymphocytes, plasma cells and macrophages replace neutrophil polymorphs
What are the systemic effects of inflammation
Pyrexia
Weight Loss
Reactive hyperplasia of reticuloendothelial system
Haematological changes
Amyloidosis (deposition of amyloid in various tissues)
How is pyrexia caused
Polymorphs and macrophages produce endogenous pyrogens which act on hypothalamus to set the thermoregulatory mechanisms at a higher temperature
Name an endogenous pyrogen
IL-2
Why does inflammation cause weight loss
Due to negative nitrogen balance
Define hyperplasia
Enlargement of organ or tissue due to increased proliferation
Describe three haematological changes caused by inflammation
Leucocytosis
Anaemia
Increased erythrocyte sedimentation rate
What are the main causes of chronic inflammation
- Transplant rejection
- Progression from acute
- Recurrent episodes of acute
What is the most common scenario in which acute -> chronic
Suppurative type
Presence of ingestible material (e.g. keratin) - constant suppuration
How does suppurative cause acute -> chronic
- If the puss forms an abscess cavity that is deep-seated and drainage is delayed causing abscess to develop thick walls composed of granulation and fibrous tissue
- Rigid walls of abscess cavity therefore fail to come together after drainage
- Cavity becomes organised by ingrowth of granulation tissue
What type of chronic inflammation is caused by foreign bodies
Granulomatous inflammation
What is granulomatous inflammation
Macrophages form multi-nucleate giant cells
Example of recurrent acute inflammation
Cholecystitis where acute causes wall muscle of gallbladder to be replaced by fibrous tissue
Predominant cell type is lymphocyte rather than neutrophil polymorph
What are the five most common appearances of chronic inflammation
- Chronic Ulcer (e.g. of the stomach)
- Chronic abscess cavity
- Thickening of the wall of a hollow viscus by fibrous tissue
- Granulomatous inflammation
- Fibrosis
Define Fibrosis
Thickening of connective tissue
What does the cellular infiltrate of chronic inflammation consist of
Lymphocytes (B and T) Plasma Cells Macrophages Eosinophil Polymorphs (very few) Granulation tissue forming fibrous tissue
What happens to macrophages during delayed-type hypersensitivity responses
They die forming large areas of necrosis
What is a granuloma
Aggregate of epithelioid histiocytes and lymphocytes
Characteristics of epithelia histiocytes
- Large vesicular nuclei
- Large eosinophilic cytoplasm
- Elongated
Are epithelia histiocytes phagocytic
Very little
What do epithelioid histiocytes secrete
ACE
What is a marker for systemic granulomatous disease
Activity of ACE
How can granulomas be characterised
- Histiocytes become multinucleate giant cells
What indicates if granuloma is from a parasitic infection
Granulomas associate with eosinophils
Where do hisitiocytic giant cells form
Where particulate matter is indigestible by macrophages accumulate (e.g. bacterial cell walls)
OR
when foreign particles are too large to be ingested by just one macrophage.
Are histiocytic giant cells functional
No - very little phagocytic activity
When are longhand giant cells seen
In TB under granulomatous conditions
What are foreign body giant cells
Large cells with nuclei randomly scattered through their cytoplasms
What are defining features of foreign body giant cells
No distinctive features
What organ do disease affecting it result in inflammation
Heart
What are exudates
Have high protein contents as they form from increased vascular permeability
What are transudates
Low protein content from normal permeability of vessels
What is a granuloma
Aggregate of epithelioid histiocytes
What is granulation tissue
Component of healing consisting of small blood vessels in a connective tissue matrix with myofibroblasts
