how does the immune system work for individual tissues
- most tissues have specialised “resident” immune cells
- e.g. the skin has Langerhans cells, the brain has microglia
what does tolerance mean
the mechanism by which the immune system avoids attacking the body’s own cells and harmless substances
in what cases do we not want our immune system attacking non-self
eating food, transplants, fetus growing
what are the functions of the immune system
distinguishes self from non-self in order to:
- protect against infection
- recover from infection and tissue damage
- detect and eliminate (self) tumour cells
- maintain adequate relationship with environment and good microbes
how does the immune system respond to shapes
- recognises unusual shapes
- recognises familiar shapes in unusual contexts
why is “context” important for the immune system
moving a beneficial bacteria from the gut to the brain can make it turn harmful
what do we want our immune system to recognise
(bad)
- viruses
- bacteria
- fungi and yeasts
- parasites
what else does our immune system to recognise other than pathogens
- virus components
- dust particles
- chemical polymers (in drugs)
- foods
- cells from other people (transplants)
- yourself (negatively - autoimmune disease)
- cancer cells (positively - targeting cancer cells)
how do pathogens reach the inside of our body
the must first breach biophysical and biochemical defenses
describe the biophysical defenses we have
- mucus
- cilia lining the respiratory tract
- acid in stomach
- skin
describe the biochemical defenses we have
lysozome enzymes in (most) secretions
what are the adaptive immune cells
T lymphocytes and B lymphocytes
how does the immune system use blood
it uses it as a transport mechanism
where are immune cells found in our body
- blood
- tissues and organs
- intestine and gut
- lymphatic system
where are immune cells found in tissues and organs
- almost all tissues/organs have a resident INNATE immune system
- particularly abundant in barrier forming tissues e.g. skin
where are immune cells found in intestine and gut
highly developed INNATE and ADAPTIVE system specialised in dealing with the gut microbiota
why do doctors take a blood sample for checking on our immune system
immune cell counts in blood are easy to measure
what is the proportion of immune cells in the blood
1) ~70% neutrophils
remaining 30%:
2) 60-70% T cells
3) 10% monocytes
4) 10-20% NK cells
5) 10% B cells
what are the 2 types of immune responses
- innate (non-specific)
- adaptive
what cells encompass the innate immune response
- neutrophils
- macrophages
- natural killer cells
- mast cells
- monocytes
- some antigen-presenting cells
what enzymes/proteins are secreted under the innate immune response
- lysozymes
- complement
- acute phase proteins
- interferons
- danger sensing receptors
- cytokines
what do danger sensing receptors do
in the innate immune system, they detect danger (changes) in the cell they belong to as well as around the cell
describe the nature of the innate immune response
- rapid responses
- prevent infection spreading to other parts of body
- no memory cells generated!
what is the timeline of an immune response
1) initial exposure
2) resident immune cells detect pathogens and travel
- signals can also be sent from the site of infection to recruit lymphocytes from the blood to said site
3) phagocytosis occurs
4) phagocytes can deliver components of the bacteria (antigens) to the adaptive immune cells (in the lymph nodes)
