Components Of The Immune System Flashcards
What is the most fundamental function of the immune system?
Ability to recognize self and nonself
Must be nonreactive to self
What are the two types of immunity?
Innate and acquired
What are the characteristics of the innate immune system?
- Nonspecific
- Elements we’re born with
- Available on short notice
- Physical and chemical
What are the characteristics of the acquired immune system?
- Specialized
- Acquired after contact with a particular agent
- Immunization happens with first contact
- Creates immunity to attacks from the same agent in the future
What is immunization?
- Part of gaining acquired immunity
- Contact with an agent triggers lymphocyte activation and antibody production
What cell lineage are adaptive immune cells derived from?
Mainly lymphoid, but some cells from the myeloid lineage have a role in adaptive immunity
What cells are derived from the myeloid lineage? (6)
- Macrophages
- Dendritic cells
- Neutrophils
- Eosinophils
- Basophils
- Mast cells
What do macrophages do?
- Phagocytosis and activation of batericidal mechanisms
- Antigen presentation
Where are macrophages found?
Mainly in tissues
What are macrophages derived from?
Myeloid lineage, blood monocytes
What do dendritic cells do?
- Antigen uptake in peripheral sites
- Antigen presentation in lymph nodes
Where are dendritic cells found?
Lymphoid organs
What are dendritic cells derived from?
Myeloid lineage, monocytes
What do macrophages and dendritic cells have in common?
- Antigen presentation
- Innate immune response
- Phagocytosis
What is the function of neutrophils?
- Phagocytosis
- Activation of bactericidal mechanisms
What is the function of eosinophils?
Killing antibody-coated parasites
Name the granulocyte cells
- Neutrophils
- Eosinophils
- Basophils
Why are granulocytes referred to as polymorphonuclear cells?
Have an oddly shaped nucleus with one or more lobes
What is the function of mast cells?
Release of granules with histamine and other active agents
What do basophils and mast cells have in common?
- Found in tissues
- Respond to parasites
- Release mediators that make endothelium more permeable —> neutrophils reaching tissue from circulation
Where do B-cells mature?
In the bone marrow
What do B-cells do?
- Have antigen-specific Ig receptors
- Activated B-cells differentiate into plasma cells
- Plasma cells make antibodies specific to antigen
- Adaptive immunity
Where do T-cells mature?
In the thymus
What is the receptor on T-cells called?
T-cell receptor (TCR)
What are the main types of T-cells?
- CD4 helper T-cells
- CD8 cytotoxic/killer T-cells
What do CD4 T-cells do?
- Recognise antigens presented to them by APCs
- Activate other immune cells (CD8, B cells, macrophages)
- Specialize into subsets to coordinate immune response
- Memory formation for future immune response
Where do natural killer cells mature?
In the bone marrow
What do natural killer cells do?
- Innate immune response
- Kill cancer and virus infected cells
- Have some function in adaptive immunity
Why is the thymus important?
- T-cell maturation site
- Removes self-reactive T-cells
Where are plasma cells found?
- Lymph nodes
They are B-cells that have been triggered by an antigen
What can finding plasma cells in the blood be indicative of?
Cancer - myeloma
What are the 3 antigen presenting cells?
- Dendritic cells
- Macrophages
- B-lymphocytes
What do antigen presenting cells do?
- “Chew up and spit out”
- Digest antigen and present peptides via MHC class II molecules to CD4 cells
- Link between innate and adaptive immune system
Why do lymph nodes swell with infection?
Response to infection
1) Proliferation of immune cells
2) Inflammatory response to immune system signals
3) Accumulation of pathogen and immune cell debris
4) Localized infection of lymph node
How do immune cells find pathogens to respond to them?
Lymphocyte recirculation
- Lymphocytes enter the lymphatic system and adhere inside lymph nodes
- Lymph from infection site reaches nearest lymph node (draining lymph node)
- Immune response ensues
