Overview of immunity
What is the immune system and why is it important?
Components of the IS
White blood cells (leukocytes) e.g. macrophages, dendritic cells, b cells, t cells and
neutrophils.
Antibodies are produced by b cells to bind to antigens, mark pathogens for
destruction, and neutralise toxins.
T cells: several types e.g. helper, cytotoxic and regulatory. It helps kill infected cells
and regulate IS activity.
Lymphatic system: helps clear pathogens from the bloodstream
Bone marrow: makes blood cells and matures t cells.
Inflammatory response: allows immune cells to be brought to the site of infection or
injury to facilitate their response.
This can be split into innate and adaptive.
Why it is important:
Disease prevention
Protection against cancer
Respond to infections.
Immune memory
Homeostasis (balanced internal environment)
Vaccination to prevent infection.
Autoimmune disease regulation.
Differentiation of immune cells
All start as hematopoietic stem cells
In the bone marrow they either specify into lymphoid or myeloid
Myeloid: innate
Lymphoid: adaptive
, Innate immune cells
Neutrophils:
o Highly mobile.
o Arrive at the site of infection.
o Engulf and destroy bacteria via phagocytosis.
Macrophages:
o Large cells that are phagocytic
o Patrol tissues to look out for foreign matter.
o Engulfs pathogens, dead cells and debris.
o Activated by pathogen-associated molecular patterns (PAMPs)
Dendritic cells:
o Captures antigens from pathogens.
o Presents them to T cells.
o Bridge the gap between innate and adaptive response (more so than
macrophages).
Basophil:
o Release histamine
o During allergic reactions
o Inflammatory response
Mast cell:
o Similar to basophils
o But they patrol tissues.
o And release histamine when they see an allergen.
o So compared to basophils, they are already on the scene like security
guards.
o Also releases factors to increase blood flow so cells reach the site of
infection.
Eosinophil:
o Releases enzymes to damage parasites
o Modulates inflammation too during allergic reactions.
Natural Killer cells:
o Cytotoxic cells
o Recognise and destroy infected cells.
o Virus-infected cells and cancer cells specifically
What is the immune system and why is it important?
Components of the IS
White blood cells (leukocytes) e.g. macrophages, dendritic cells, b cells, t cells and
neutrophils.
Antibodies are produced by b cells to bind to antigens, mark pathogens for
destruction, and neutralise toxins.
T cells: several types e.g. helper, cytotoxic and regulatory. It helps kill infected cells
and regulate IS activity.
Lymphatic system: helps clear pathogens from the bloodstream
Bone marrow: makes blood cells and matures t cells.
Inflammatory response: allows immune cells to be brought to the site of infection or
injury to facilitate their response.
This can be split into innate and adaptive.
Why it is important:
Disease prevention
Protection against cancer
Respond to infections.
Immune memory
Homeostasis (balanced internal environment)
Vaccination to prevent infection.
Autoimmune disease regulation.
Differentiation of immune cells
All start as hematopoietic stem cells
In the bone marrow they either specify into lymphoid or myeloid
Myeloid: innate
Lymphoid: adaptive
, Innate immune cells
Neutrophils:
o Highly mobile.
o Arrive at the site of infection.
o Engulf and destroy bacteria via phagocytosis.
Macrophages:
o Large cells that are phagocytic
o Patrol tissues to look out for foreign matter.
o Engulfs pathogens, dead cells and debris.
o Activated by pathogen-associated molecular patterns (PAMPs)
Dendritic cells:
o Captures antigens from pathogens.
o Presents them to T cells.
o Bridge the gap between innate and adaptive response (more so than
macrophages).
Basophil:
o Release histamine
o During allergic reactions
o Inflammatory response
Mast cell:
o Similar to basophils
o But they patrol tissues.
o And release histamine when they see an allergen.
o So compared to basophils, they are already on the scene like security
guards.
o Also releases factors to increase blood flow so cells reach the site of
infection.
Eosinophil:
o Releases enzymes to damage parasites
o Modulates inflammation too during allergic reactions.
Natural Killer cells:
o Cytotoxic cells
o Recognise and destroy infected cells.
o Virus-infected cells and cancer cells specifically
