innate and adaptive immunity

innate immunity - mechanical defence

body surface = skin, fur

cilia in respiratory tract

air movement in respiratory tract

flushing by fluids e.g tears, urine, diarrhoea

mucus as barrier 

immunity

CMP = common myeloid progenitor

CLP = common lymphoid progenitor

innate immunity

first line of defence with multiple forms - mechanical, molcular/cellular, microbiological and enviromental 

• natural or non-specific

• speed

• memory

• specifity

innate immunity - physiological defence

pH changes and extremes

pyrexia kills some infectious agents 

cellular innate defences

monocyte - only in blood stream, then becomes a macrophagein tissue

macrophages - function by ingesting and killing microorganisms

neutrophils - phagocyctic and degranulate

mast cells/ basophils/ eosinophils

basophil

eosinophil

neutrophil

molecular defences 

defensins

lysozyme and sweat gland secretions

myeloperoxidase system 

acute phase proteins

complement system 

interferons 

defensins

small proteins(15-20 amino acids)

found in many tissues and cells(esp phagocytes and epithelial cells)

active against bacteria, fungi and viruses(bind microbe membrane)

important in skin barrier to infections 

lysozymes

family of enzymes which attack peptidoglycan cell walls of bacteria

sites of action =

• cellular - cytoplasmic granules of macrophages

• secreted from epithelial cells - tears, saliva, mucus

• sebum - from sebaceous glands, waxy - fatty acids - stop bacterial attachment to skin, hydrates and lubricates skin 

myeloperoxidase

enzyme found mainly in lysosomes in granulocytes and macrophages

kills bacteria and other pathogens by production of toxic hypochlorite(OCl-) and single oxygen(O2)

innate immunity - microbiological defence commensal bacteria

inhabit mucosal surfaces, esp in GI, respiratory tracts and skin

innate immune system is always primed and functioning against commensal bacteria but it has a tolerance which prevents inflammation

prevent attachment of pathogenic bacteria and block invasion and infection 

enviromental/ management effects on innate immunity

husbandry - diet, temp and humidity

form of immunodeficiency 

adaptive immunity

built from 2 cells - T and B cells(lymphocytes)

defining features = specificity, self/ non-self discrimination, memory 

all adaptive immune cells go through maturation in thymus, to make sure that all of B and T cells you have in your body do not recognise any part of self 

B and T cells in body will recognise any antigen presented to them

antigen

any molecule that can bind specifically to an antibody or antigen recpetor

epitope

site on an antigen recognised by an antibody or an antigen receptor

antibody

protein that binds specifically to particular substance

recognises a specific epitope

primary and secondary immune responses

vaccine contains antigen which has specific epitope

innate immune system then present it to adaptive immune system

one of T-cells or B-cells will recognise it and undergo clonal expansion to multiply - takes time and dies down 

t or b cell goes through selective process to make bind better

once dies off still exists as memory cell in blood 

primed and ready to expand 

so if reinfection occurs the second response is faster and larger

so adaptive immune system is most useful in re-infections 

stages of action - defending against microbial invasion