LF127 Lectures 9-14: intro to immunology

Two ways pathogens can evolve

muation or recomination

mutation

rapid replication means lots of chance for mutation

recombination

RNA segment recombination creates changes that can jump speciea

antigenetic shift

virulence strategy where some pathogens alter surface protiens to stay undetected

Adaptive immune systemm

slow, specific and has memory

innate immune system

fast, no memory and not specific

role of innate immune system

to fight colonies that grow faster then the adaptive can fight. via barrieres, cell intrinsic responses and specialised proteins.

mucus layer

protect against microbial, mechanical and chemical attacks via slipperiness, cilia and mucins

defensins

very toxic antimicrobial peptides with domains. can cause lysis. dont harm human cells as they contain cholesterol

complement system

if pathogens breach epithelial barrier it can recognize them via its soluble receptors

Toll like receptors

transmembrane protein with a large extracellular domain and repeating motifs. causes transcription when pathogens are detected

neutrophils

most common phagocyte. short lives and abundant in blood but not healthy tissues

macrophages

larger and longer lives phagocytes. recognize, remove and ingest dead and damages cells

eosinophils

help destroy parasites and modulate allergic reactions

granules

dense, membrane bound lysosomal derivatives which fue with phagocyte membranes and release contents.

inflammation

aids the killing frenzy by swelling blood vessels and causing component accumulation. can lead to sepsis

natural killer cells

persuade infected cells to apoptosis

lymphocytes

type of white blood cell in adaptive

dendritic cells

link innate and adaptice immune system

T- cells

thymus cells, three types cytoxic, helper and regulatort

cytoxic t cells

kill infected host cells

helper t cells

active macrophage, dendrites and maintain cytoxis

regulatory

inhibit function of others

b-cells

recognise soluble antigens, activity mitosis and colonal expansion of specific b cells

antibodies

tetrameric, 4 polypeptide chains, 2 heavy 2 light

Ig M

most primitive, has 5 bonding sites and is a pentameter with a joining chain

Ig G

standard 2H 2L and very abundant

Ig A

dimer (2 tetrameric) held by joining and sectraotry chain

Ig E

triggers degranulation and has receptors for eosinophils

Light chain

V2-C2

Heavy chain

Vh-Ch-hinge-Ch2Ch2-(Ch4)

class switching

somatic recombiantion leads to diversity which leads to class switches as loops are deleted

clonal expansion

to produce more pathogen specific lymphocytes when a pathogen is detected.