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Immunology - Lecture Thirty One : Innate immunology I

Q: What are some examples of phagocytic cells ?

MONOCYTES (in the blood) They develop into macrophages when entering the tissue Results in an increase in their phagocytosing ability Slightly phagocytic MACROPHAGES (in the tissue) Highly phagocytic Can be sessile (stationary) or migratory (moves) Functions are : phagocytosis, release of chemical messengers and resenting pathogens to T Cells to activate the adaptive immune system DENDRITIC CELLS (also in the blood and tissues) Phagocytic Found in low numbers blood and all tissues in contact with the environment Most important cell type to help trigger adaptive immunity responses

6 important questions on Immunology - Lecture Thirty One : Innate immunology I

What are the 2 types of cells in Granulocytes (innate immune lymphocytes) ?

NEUTROPHILS
75% of leukocytes which circulate in the bloodMain function is phagocytosis of pathogensHighly phagocyticNumbers of neutrophils increase when there is infectionMAST CELLS
Line mucosal surfaces (not in blood)Release granules that attract WBC's to areas of tissue damage

What are some examples of phagocytic cells ?

MONOCYTES (in the blood)

They develop into macrophages when entering the tissue
Results in an increase in their phagocytosing ability
Slightly phagocytic

MACROPHAGES (in the tissue)

Highly phagocytic
Can be sessile (stationary) or migratory (moves)
Functions are : phagocytosis, release of chemical messengers and resenting pathogens to T Cells to activate the adaptive immune system

DENDRITIC CELLS (also in the blood and tissues)

Phagocytic
Found in low numbers blood and all tissues in contact with the environment
Most important cell type to help trigger adaptive immunity responses

What is the composition of the blood ?

55% of blood is plasma (proteins, water and solutes)
45% is formed elements (platelets, WBC and RBC)
Bone marrow contains stem cells which undergo hematopoiesis to create more blood cells

The 3 main blood cell lineages are :

Erythroid (RBC)
Myeloid - innate immune lymphocytes (granulocytes, monocytes, dendritic and platelets)
Lymphoid - Adaptive immune lymphocytes (B and T Cells)

How do cells of the immune system travel around the body ?

Cells are carried in the blood to the tissues where they act
Lymph fluid is collected from tissues into the lymph vessels
Lymph vessels drain into the lymph nodes and eventually the lymph fluid drains back into the blood

How are pathogens recognised by innate cells ?

The innate immune system recognises general patterns (PAMPS or Pathogen Associated Molecular Patterns) that are common between the different types of pathogens
EXAMPLES

Viruses : Envelope, SsRNA and DsRNA
Bacteria : Cell wall, lipopolysaccharides, flagella and unmethylated CpG DNA

Toll-like receptors are a type of pattern recognition receptor. They are responsible for recognising PAMPS and then activate the immune response

How is fever reduced ?

High temperature above 37 degrees
Occurs due to the resetting of the hypothalamus by pyrogens (IL-1) which are released by immune cells
IL-1 is released when phagocytes eat pathogens to increase temperature
Decrease in IL-1 results in decrease in temperature