Flashcards in Immunology Deck (160)
what is opsonisation?
coating of pathogens by antibody, leading to increased phagocytosis.
describe the process of B cell development
arise from lymphoid progenitor cells in fetal spleen/liver.
produced in bone marrow in adults.
what is active immunisation?
challenge subjects immune system to induce immunity. production of high affinity antibodies against immunogen. induction of immunological memory.
what is passive immunisation?
transfer of preformed antibodies to the circulation.
can be natural or artificial.
what is natural passive immunity? what does it protect against?
transfer of maternal antibodies across placenta to foetus.
what are the indications for use of artificial passive immunity?
individuals with agammaglobulinaemias (B cell defects) - given normal human IgG.
exposure to disease at risk of complication.
when there's no time for active immunisation to give protection - pathogen with short incubation period.
acute danger of infection.
how do anti-toxins work?
give passive immunity, as for some pathogens the main hazard is not the primary infection, but the toxins released by the pathogen.
e.g. tetanus, botulinum, diptheria.
what are anti-venins?
substances that provide passive immunity to venoms
e.g. snake bite, insects, jellyfish
what are some disadvantages of passive immunisation?
doesn't active immunological memory - no long term protection.
may react to anti-sera used.
vaccination involving introduction of a viable microorganism into the subject
what are the aims of a "perfect" vaccine?
1. achieve long term protection from a small number of immunisations (compliance)
2. stimulate B and T cells
3. induce memory B and T cells
4. stimulate protective high affinity IgG production
describe the primary immune response
relies on innate immune system.
describe the secondary immune reponse
rapid and large reaction.
high affinity IgG.
T cell help.
doesn't rely on innate immune system.
name some different types of vaccine
whole organism - live attenuated pathogen; killed, inactivated pathogen.
subunit - toxoids; antigenic extracts; recombinant proteins
what are some advantages of live attenuated vaccines?
sets up a transient infection. full immune response activated. prolonged contact with immune system. stimulation of B and T cell memory.
often single immunization.
what are some disadvantages of live attenuated vaccines?
can cause infection in immunocompromised patients.
can occasional revert to a virulent form, can cause a serious outbreak in poor sanitation.
refrigeration and transport are issues.
what are some advantages of whole inactivated pathogen vaccines?
no risk of infection.
storage less critical than a live vaccine.
good immune response possible.
what are some disadvantages of whole inactivated pathogen vaccines?
tend to just activate humoral response - lack of T cell response.
immune response can be quite weak - booster vaccinations needed, compliance can be a problem.
what are some advantages of subunit vaccines?
safer than live/inactivated pathogens.
no risk of infection.
easier to store/preserve
name some types of subunit vaccine?
what are some disadvantages of subunit vaccines?
immune response less powerful than to live attenuated vaccines.
repeat vaccinations/adjuvants needed.
give examples of adjuvants that could be added to a vaccine to stimulate the immune system?
whole killed organisms.
chemicals - aluminium salts, paraffin oil.
how do DNA vaccines work?
transiently express genes from pathogens in host cells. generates immune response - T and B cell memory.
what are some advantages/disadvantages of DNA vaccines?
easy to store/transport
simple delivery (DNA gun).
BUT - no transient infection, likely to produce mild response and require boosters.
how do recombinant vector vaccines work?
imitate effects of transient infection with pathogen, but using a non-pathogenic organism.
genes for pathogen antigens introduced into non-pathogenic microorganism and introduced to host.
what are some advantages/disadvantages of recombinant vector vaccines?
can create ideal stimulus to immune system - memory.
flexible and safe.
BUT - need refrigeration. can cause illness in immmunocompromised.
what is cancer immunosurveillance?
idea that immune system can recognise and destroy newly transforming/transformed cells
what is cancer immmunoediting?
immune system can protect you from cancer by killing tumour cells. but they're very genetically unstable - so immune responses to tumours can cause changes in tumour cells, allowing tumour escape and recurrence
what are tumour specific antigens?
found only on tumours. result of point mutations/gene rearrangement. derive from viral antigens.