Immunology Flashcards
(40 cards)
what are the two types of immunity?
- passive
- active
what is passive immunity and when does this occur naturally?
- the transfer of pre-formed antibodies to a susceptible individual giving temporary protection from infection
- occurs naturally - mother to baby via the placenta and breast milk
what are some examples of live attenuated (weakened) vaccines?
- Tuberculosis (BCG vaccine)
- MMR (measles, mumps, rubella)
- varicella-zoster (chicken pox)
- rotavirus
- yellow fever
- oral typhoid
- intra-nasal influenza
- oral polio (Sabin)
what are the advantages of using a live attenuated vaccine?
- immunogenic (resembles a natural infection)
- replicates in patient, excellent immune response
what are the disadvantages of using a live attenuated vaccine?
- not suitable for high risk groups (pregnant women, immunocompromised)
- can potentially develop the vaccine strain infection
- need mature adaptive immune system
what is inactivated whole cell immunity?
- pathogen is killed by chemical or physical processes and then inserted into patient
- cannot give the patient the infection as it’s dead, and therefore high risk groups can have it but immune response may not be great
Give an example of an inactivated whole cell vaccine.
- inactivated polio (Salk)
- hepatitis A
- rabies
what is inactivated toxin (toxoid) immunity and give an example of a vaccine
- toxins which are chemically treated to elimate toxicity whilst maintaining immunogenicity (eg. with formaldehyde)
- eg. Diphtheria, Tetanus
what is subunit immunity and give an example of a vaccine
- a bit of a virus or bacteria is inserted
- cannot infect patient as not whole pathogen
TWO TYPES: - recombinant proteins (eg. Hepatitis B, Papillomavirus)
- chemically purified (eg. Acellular pertussis, influenza)
what is polysaccharide immunity and give an example of a vaccine
- poorly immunogenic in young children so not used for children
- T-cell independent - no memory cells produced
- eg. some meningococcal, some pneumococcal, salmonella
what is conjugated polysaccharide immunity, what are some advantages over polysaccharide immunity, and give an example of a vaccine
- purified bacterial polysaccharide is joined to a protein
- T-cell dependent - memory cells produced
- more immunogenic than polysaccharides on their own and is used in children
- eg. Haemophilus influenzae, pneumococcal, meningococcal
what are adjuvants and what are the most commonly used?
- agents that stimulate the immune system
- aluminum phosphate and aluminum hydroxide are commonly used
- thought to work by keeping the antigen at the site of infection for longer. causing inflammation, and attracting immune cells to the site of infection
which two vaccines are people advised to get at age 65?
- pneumococcal polysaccharide vaccine
- annual influenza vaccine
which vaccine are people advised to get at age 70?
- varicella-zoster (shingles)
which two vaccines are pregnant women advised to have?
- influenza in any trimester
- pertussis (whooping cough) from 16 weeks gestation
give some examples of when post-exposure vaccines would be given.
- wounds at high risk of tetanus (specific immunoglobulin given)
- potential rabies exposure (course of vaccine + specific immunoglobulin given)
- unvaccinated contact with confirmed measles case (vaccine given)
what are some commonly seen side effects of vaccines?
- local reactions (pain, swelling, redness)
- general systemic effects (fever, headache, malaise)
- some vaccines may be associated with a rash (eg. MMR, VZV)
- anaphylaxis is very rare
what are the main contra-indications for receiving a vaccine?
- history of anaphylaxis to previous vaccine
- immunosuppression (patient or household contact)
- pregnancy
- acutely unwell
- other vaccines given recently
- immunoglobulin therapy
what are some reasons for why a vaccine might fail?
- no vaccine is 100% effective
primary vaccine failure (fail to mount an immune response to a vaccine):
- vaccine factors (eg. administration error, manufacturing error, incomplete strain coverage)
- host factors (eg. immunodeficiency)
secondary vaccine failure (immunity develops initially but decreases over time)
can a child’s immune system be overwhelmed by giving too many vaccines?
- NO!
What are the three main differences between innate and adaptive immune responses?
Innate…
- Fast (occurs within minutes)
- Low specificity
- Does not have memory function
Adaptive…
- Takes several days to develop
- Highly specific
- Memory cells are produced
Describe the anatomy of the immune system (bone marrow, thymus gland, lymph nodes, spleen, liver).
- Bone marrow: immune cells are made here during haematopoiesis
- Thymus gland: where lymphocytes mature and receive their immunological education before being released into the bloodstream
- Lymph nodes (situated along the lymphatic vasculature throughout the body): mature lymphocytes migrate to lymph nodes, these provide a site for antigen presentation
- Spleen: basically a massive lymph node, another site of antigen presentation to mature lymphocytes
- Liver: another site of antigen presentation, contains its own cohort of phagocytes and lymphocytes (important as the liver filters large volumes of potentially contaminated venous blood from the GI tract, it also synthesises acute phase proteins such as CRP in response to infection)
Describe some of the barrier mechanisms of the immune system.
- intrinsic epithelial barriers: exist between the body and the outside world. Epithelial cell walls have very tight junctions between them and are therefore hard to penetrate. (eg. linings of mouth, nasal passages, upper airways, lungs, GI tract)
- the continuous longitudinal flow of air or fluid: through most body systems helps to create a flushing action which prevents adherence of bacteria to structures where they could proliferate and invade
- movement of mucus by cilia in the lungs: helps prevent the stagnation of secretions and the adherence of inhaled droplets and particles (mucus is moved upwards towards the pharynx, where it is then swallowed or coughed up)
- desquamation of skin and epithelial cells: also prevents adherence of microorganisms
- natural acids persist in many parts of the body: eg. fatty acids on skin, lysozymes in saliva and hydrochloric acid in the stomach
- natural antibacterial peptides: on the skin and the surface linings of the lungs and gut (eg. cathelicidins, defensins, proteinase inhibitors and chemokines)
- normal bacterial flora: colonise various parts of the body and compete with infective microorganisms, and some also produce antimicrobial substances (eg. vaginal lactobacilli produce lactate, which creates an acidic environment and destroys many potentially infectious organisms)
What are the 3 types of granulocytes?
Granulocytes = family of WBCs containing granules in their cytoplasm
- Neutrophils: make up most of WBCs, first line of defence against all infections, act by phagocytosing pathogens and presenting antigens to the immune system
- Eosinophils: act against multicellular parasites (eg. worms) and involved in IgE-mediated allergic disorders (eg. asthma)
- Basophils: thought to have roles in inflammation, parasitic infections, and allergic reactions (important role in type 1 hypersensitivity reactions through their binding with IgE antibodies)
