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18 Cards in this Set
- Front
- Back
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What is passive immunisation ? |
• Transfer of active humoral immunity in the form of ready-made Ab. High titre Ab from immune donor or immune cells (adoptive transfer) – humoral components. |
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length of passive immunisation |
• Restricted to lifespan of transferred component (6 months) |
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natural passive immunisation |
Maternal transfer of IgA (placenta) and IgA (colostrum - breastmilk) – transferred to gut of infant until infant can synthesise its own Abs. Only lasts 4-6 months |
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artificial passive immunisation |
Used to prevent hypogammaglobinaemia and to treat poisoning. Anti-venins, post-natal transfer of IgG anti-D Ab that take out foetal RhD-positive erythrocytes in maternal blood (who are Rh-negative) before maternal immune system can react with them – prevents haemolytic disease of new-born. Risk of hypersensitivity and serum sickness. Immediate protection but no memory. |
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when is passive immunisation used? |
• Used when high risk of infection and insufficient time for the body to develop its own immune response
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what is Active immunisation? |
induction of immunity after exposure to an antigen. Creates Abs - protective |
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Explain the memory cells in Active immunisation |
• Memory B cells – displays more effective Ig isotypes, produces high affinity Ab (somatic hypermutation), proliferate more rapidly, longer lived, express CD27 • Memory T cells – long lived (maintained by IL7 and IL15), survive without antigen, CD8 memory requires CD4 T cell. |
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What is an • Immunodominant response ? |
Against few antigenic peptides – eliminates pathogen fast and effectively but unfavourable with high mutation rate of virus. |
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Killed whole pathogen: Advantage/disadvantage and examples |
Ad: Likely to contain whole repertoire of epitopesStable in storage Dis: Injected, needs boosters, inactivation can compromise epitopes E.g. Heat inactivation, lyophilization (dried out) Pertussis (whooping cough) |
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Attenuated pathogen: Advantage/disadvantage and examples |
Long term immunity, antigens not affected, weak infection allows presentation by cell types Not safe for immunocompromised recipients – lack of immune memory is masked by Ab of mother, sensitive to storage (cold chain), mutate to virulent form (rarely) Adapt to grow on non-human cells or lower temps - MMR |
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Subunit vaccines: Advantage/disadvantage and examples |
Ad: Likely to contain whole repertoire of epitopesStable in storage Dis: Injected, needs boosters, inactivation can compromise epitopes E.g. Heat inactivation, lyophilization (dried out) Pertussis (whooping cough) |
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Toxoid : Advantage/disadvantage and examples |
Toxins retain antigenic repertoire
Very effective Inactivation of the exotoxins of pathogenic bacteria with heat or chemicals – tetanus |
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Synthetic (recombinant): Advantage/disadvantage and examples |
No chance of disease transmission. Typically stable Can be engineered to avoid side effects Very expensive so small molecules used which contain v. few epitopes. Hep B - humoural immunity to Hep B surface antigen (HBsAg) is protective |
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What is an - Adjuvant? |
can provide exogenous/extra PRR ligands to act as non-specific stimulators of immune cells. |
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Examples of adjuvant? |
– oil emulsions, inorganic Al salts (alum). |
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how do adjuvants |
depot enabling extended exposure activate APCs. Stranger and danger signals – IL33 produced by non-haematopoietic cells and released after necrosis – IL33 receptor expressed by lymphoid cells. Some trigger innate viral/bacteria sensor pathways, via TLRs and proteins of NOD-like receptor family |
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What is a - Multivalent vaccine? |
immunise against multiple strains of same microbe |
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mechanisms for adjuvants |
Help in translocation of Ag to lymph nodes where they can be recognised by T cells - heightened clearance of pathogens Physical protection to Ags - prolonged delivery Greater release of danger signals by chemokine releasing cells - Th and mast cells |
