Session 3 - Chronic inflammation

Question 1

Which signs of inflammation resolve and which persist in chronic inflammation?

Answer 1

Redness and heat will resolve however swelling and pain will persist.

Question 2

How does chronic inflammation arise?

Answer 2

1. When it takes over from acute inflammation - most common
2. When it begins without any acute inflammation - eg. in some chronic conditions such as TB, autoimmune diseases such as rheumatoid arthritis, prolonged exposure to toxic agents, etc.
3. When it develops alongside acute inflammation - eg. an on-going bacterial infection.

Question 3

What does chronic inflammation look like under the microscope?

Answer 3

• Macrophages and lymphocytes are the most predominant cell type rather than neutrophils
• granulation tissue forms

Question 4

What is the lifecycle of a macrophage?

Answer 4

Several months.

Question 5

What are the functions of a macrophage?

Answer 5

• Phagocyte
• Antigen presenting cell
• Stimulates angiogenesis
• Secretes over 100 substances that summon and activate other cells
• Induces fibrosis
• Induces fever, acute phase reation and cachexia.

Question 6

What do fibroblasts produce?

Answer 6

Collagen, elastin and glycosaminoglycans.

Question 7

What is this cell called and what is its function?

Answer 7

Langhans giant cell - nuclei are arranged around the periphery of the giant cell and they are often but not exclusively seen in TB.

Question 8

What is this cell called and what is it for?

Answer 8

This cell is called a foreign body giant cell. The nuclei are arranged randomly in the cell and are seen when a hard to digest foreign body is present. If the foreign body is small it is phagocytosed by the giant cell and can be seen within it.

Question 9

What cell is this called and what is it for?

Answer 9

Touton giant cell - the nuclei are arranged in a ring towards the centre of the cell and they form in lesions where there is a high lipid content such as fat necrosis and xanthomas (fatty deposits that form on tendons as a result of hyperlipidaemia).

Question 10

What are some of the negative consequences of chronic inflammation on the body?

Answer 10

• Fibrosis and impaired function - a result of over-stimulation of fibroblasts by cytokines.This is helpful initially however can happen in excess and can replace normal parenchymal tissue with fibrous tissue and impair organ function.
• Inappropriate immune responses - hayfever, allergies, etc.

Question 11

What is a granuloma?

Answer 11

A granuloma is the body’s way of dealing with particles that are poorly soluble/difficult to eliminate.They often contain epithelioid cells.

Question 12

What is an epithelioid cell?

Answer 12

This is a differentiated macrophage that looks similar to an epithelial cell - they are elongated, have eosinophilic cytoplasm and appear tightly packed together.

Question 13

What is this cell? Where do you find it clinically?

Answer 13

This is showing a Reed-Sternberg cell. This is a specific type of giant cell that you find in Hodgkin’s lymphoma.

Question 14

What does a rheumatoid nodule look like macroscopically?

Answer 14

There is central fibroid necrosis with palisading macrophages around the outside of it.