S3L1 - Chronic Inflammation

Question 1

What happens after acute inflammation?

Answer 1

1. Complete resolution
2. Repair with connective tissue (fibrosis)
3. Progression to chronic inflammation (prolonged inflammation with repair

Question 2

What is chronic inflammation?

Answer 2

Prolonged inflammation with associated repair.
It has a delayed onset, has a variety of cells (not just neutrophil such as with acute) variable duration (from days to years), has variable appearances (not necessarily 5 cardinal features), aim is to limit damage and initiate repair but can cause debilitating symptoms whilst doing so.

Question 3

How does chronic inflammation arise?

Answer 3

1. Takes over from acute inflammation
2. Develops alongside acute inflammation (in tandem)
3. Arises “de novo”- with our preceding acute inflammation such as autoimmune conditions

Question 4

What is a macrophage?

Answer 4

Within circulation a macrophage is called a monocytes and then develops into a macrophage once it enters the tissue spaces. Macrophages are very large and have a variable structure, depending on what they are phagocytosing. They have an abundant foamy cytoplasm and a slipper shaped nucleus.
Macrophages main role is in phagocytosis of pathogens/necrosis/debris. Also synthesise and release inflammatory mediators, releasing chemicals that control and regulates inflammatory response.

Question 5

Describe the cell types in chronic inflammation

Answer 5

Generally non -specific but occasionally we can indicate a diagnosis based on the cell types.
Rheumatoid arthritis = mainly plasma cells
Chronic gastritis = mainly lymphocytes
Leishmaniasis = mainly macrophages.
More cell variety than acute inflammation

Question 6

What effects occur during chronic inflammation

Answer 6

Fibrosis - deposition of collagen, can be seen in liver cirrhosis

Atrophy - reduction in the size of an organ, strophic gastritis where lining of the stomach decreases.

Stimulation of immune response - prolonged inflammation as antigens are continuously presented

Impaired function - inflammatory bowel diseases. Occasionally there is increased function such as thyrotoxicosis in Graves’ disease.

Question 7

What is a granuloma?

Answer 7

A spherical collection of epithelioid histiocytes. These are macrophages that are surrounded by lymphocytes.
May get a giant cell within a granuloma

Question 8

What cells develop from a common myeloid?

Answer 8

Megakaryotypes through thrombopoiesis (producing thrombocytes)

Erythrocytes (erythropoiesis)

Mast cells

Myeloblasts (which differentiate further to form granulocytes such as basophils, neutrophils, eosinophils and monocytes/macrophages)

Question 9

What do common lymphoid progenitor cells differentiate into?

Answer 9

Develop into:
Lymphocytes (T, B and plasma cells)

Natural killer cells (large granula lymphocyte)

Natural killer cells (large granular lymphocyte)

Small lymphocyte such as T lymphocytes and B lymphocytes that differentiate further into plasma cells

Question 10

What is a lymphocyte?

Answer 10

Small cells, slightly larger than RBC, spherical nucleus with very little thin surrounding cytoplasm. Are both leukocytes (T cells and B cells) involved in adaptive immune response.
Cannot distinguish T cells and B cells by appearance, need to do immuno chemistry test to check surface immunoglobins.

Question 11

What is a T cell?

Answer 11

A form of lymphocyte, there are a variety of types.
Helper T cells assist other inflammatory cells
Cytotoxic T cells destroy pathogens

Question 12

What is a B cell?

Answer 12

A form of lymphocyte that matures into a plasma cells. Produces antibodies and neutralises pathogens.

Question 13

What is a plasma cell?

Answer 13

A matured B cell. Has an Eccentric nucleus with chromatin in the nucleus arranged on the outside of the nucleus in the shape of a clock. Lighter area surrounding the nucleus is the Golgi body (peri-nuclear clearing).
Function is to produce immunoglobins

Question 14

What is an eosinophil?

Answer 14

Bilobular, granular cytoplasm which stains red/pink. Granules full of chemical mediators (histamines) that are released during allergic (hypersensitivity) reactions and in parasitic reactions.

Question 15

What are fibroblasts?

Answer 15

Cells that produce connective tissue fibres such as collagen, elastin and glycoaminoglobins. They are important in repair and regeneration.

Question 16

What are myofibroblasts?

Answer 16

Differentiated fibroblasts that contain an element of muscle, allowing them to contract.

Question 17

What are the 3 types of giant cells?

Answer 17

1. Foreign body giant cells
2. Langhans giant cell
3. Touton giant cell

Question 18

Describe the structure and function of a foreign body giant cell

Answer 18

Function is to destroy a foreign body. Nuclei are randomly located

Question 19

Describe the structure and function of a Langhans giant cell

Answer 19

Nuclei are arranged around the peripheral of the cell, often in a horse shoe shape. Often seen during mycobacterium tuberculosis

Question 20

Describe the structure and function of a touton giant cell

Answer 20

Touton giant cells have nuclei arranged in an inner circular structure. Can be seen during fat necrosis.

Question 21

What are Idiopathic inflammatory bowel diseases?

Answer 21

Idiopathic = we do not understand the cause of the disease. Inflammatory bowel disease symptoms are abdominal pain, altered bowel motions, weight loss and rectal bleeding.

1. Crohn’s disease
2. Ulcerative Colitis