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FUN1: Intro to cells + systems of the immune system (i) (Overactive/undera…
FUN1: Intro to cells + systems of the immune system (i)
Overactive/underactive immune system
overactive: autoimmunity, CV disease, neurodegeneration, pul disease, metabolic disease (diabetes)
underactive: immunodeficiency, cancer
Protective methods
1) barrier
Physical
skin
epithelium
commensal bacteria (occupy space in epithelium to form a blockade
Mechanical
tears
mucus
cilia
peristalsis
rapid epithelial shedding
Chemical
acid (gastric acid + sweat)
lysozymes
anti-microbial peptides (histamine, defensin, cathelicidins)
2) Innate
instant but non-specific
inflammation
3) Adaptive
delayed but specific
lymphocytes
antigen specific
immunological memory
Leukocytes
Innate
from myeloid progenitor cell
mast cells
neutrophils
60-70%
higher in bacterial infection
basophils
eosinophils
2-4%
higher in allergic reaction
monocytes
3-8%
higher in chronic infection
Addaptive
from lymphoid progenitor cell
T + B cells
20-25%
T helper (CD4) cells activate B cells to make antibodies
Cytotoxic (CD8) T cells kill infected cells
NK cells (viruses)
Phagocytes
recognise pathogen via Rs
engulf it into phagosome
phagosome attacked by lysosome, forming phagolysome
debris excreted by exocytosis
Macrophages, dendritic cells, neutrophils
secretory cells
have toxin releasing granules
e.g. superoxide peroxide, cationic proteins, inflamm mediators
mast cells, basophils, eosinophils
antibodies
proteins that recognise + bind to specific antigen
promotes neutralisation, aggregation, pathogen uptake