ICS Immunology Flashcards
What are the two types of immune responses in humans?
Innate and Acquired
What type of immunity is the first line of defense?
Innate
Which WBCs are most abundant in humans?
Neutrophil
Which antigen presenting cell is considered a professional at activating lymphocytes?
Dendritic cell
Which of the following is not a component of innate immune system
a) Skin
b) Antimicrobial peptides
c) Antibodies
d) Mucosa
Correct answer= C
Antigen presenting cells process and present antigens for recognition by
A) Neutrophils
B) Red blood cells
C )Eosinophils
D) T cells
Correct answer= D
Which of the following are features of the adaptive immune response
A) Does not require prior contact with the pathogen
B) It works with B and T lymphocytes
C) Lacks specificity
D) Distinguishes “self” from “non-self”
E) Enhanced by complement
Correct answer= B
Which of the following is not part of the Elimination phase of complement activation? A) Opsonisation B) Production of interferons C) Target cell lysis D) Chemoattraction of leukocytes E) Phagocytosis
Correct answer= B
Which of the following vaccines are administered as live attenuated vaccine in the UK- Hepatitis A, Tetanus, MMR, Flu, BCG?
Correct answer= MMR and BCG
Which of the following vaccines are delivered as polysaccharide vaccines- Pneumococcal disease, Influenza type B, rabies, Salmonella typhi, meningococcal disease?
Correct answer=
Pneumococcal disease
Salmonella typhi
Meningococcal disease
Influenza vaccine is targeted towards 'at risk' groups in the UK. Which of the following aren't classified as 'at risk'? A) Asthmatics B) Diabetics C) The obese of any age D) 6 months of age
Correct answer= D
Which of the following is not an organ-specific auto-immune disease? A) Type 1 diabetes B) Graves disease C) Ulcerative colitis D) Hashimoto's thyroiditis E) Sjorgren's syndrome
Correct answer= C
Which of the following is not a classical PAMPs?
A) Flagellin, a protein found in bacterial flagella
B) Lipopolysaccharide (LPS) from the outer membrane of gram-negative bacteria
C) Peptidoglycan, found in bacterial cell walls
D) Lipoarabinomannan of mycobacteria
E) Interleukin 12
Correct answer= E
Is innate or adaptive immunity more specific?
Adaptive is more specific
Is memory present in innate or adaptive immunity?
Adaptive immunity has memory
What cells are present in innate immunity?
Neutrophils, NK cells, Macrophages
What cells are present in adaptive immunity?
T cells and B cells
Name some soluble factors in immunity
Complement proteins
Antibodies
Cytokines and chemokines
What are the layers that form when centrifuging a blood sample?
- Upper fluid= 55% = plasma
- Middle layer= Buffy coat
- Lower layer= 45%= haemocrit
What is plasma composed of?
90% Water, some electrolytes, proteins, lipids, sugars
What is a buffy coat?
The middle layer that forms when centrifuging a blood sample. It is formed of leukocytes
What is haemocrit?
The cell component of a blood sample- including erythrocytes, platelets etc
What is serum?
Plasma without fibrinogen and clotting factors
Where are leukocytes made and by what process?
Made in the bone marrow by haematopoiesis
Name 3 polymorphonuclear leukocytes?
- Neutrophils
- Eosinophils
- Basophils
Name 3 mononuclear leukocytes?
- Monocytes
- T cells
- B cells
Name the different types of T cells
T-regs
T-helper (CD4, Th1 and Th2)
Cytotoxic T cells (CD8)
What are complement proteins?
Group of 20 serum proteins secreted by the liver that are activated as part of the immune system and cause a cascade.
What are the modes of action of complement proteins?
- Direct lysis
- Attraction of leukocytes to the site of infection
- Coat invading organism
Name the classes of antibody
IgG, IgA, IgM, IgD, IgE
What is an epitope?
The part of the antigen that binds to the antibody/ receptor binding site
What is the role of interferons?
Induce a state of antiviral resistance in uninfected cells
What is the role of colony stimulating factors?
Involved in directing the division and differentiation of bone marrow stem cells (Precursors to leukocytes)
What is the role of tumour necrosis factor?
Mediates inflammation and cytotoxic reactions
What is the role of chemokines?
Attracts leukocytes
Name some cytokines
Interferons, Interleukins, Colony stimulating factors, tumour necrosis factors, chemokines
Name some exterior defenses used by the innate immune system
- Skin
- Mucous and cilia in bronchi
- Flushing of the urinary tract
- Low pH and commensals of vagina
- Lysozyme in tears
What are the hallmarks of inflammation?
- Increased blood supply
- Increased vascular permeability
- Increased leukocyte transendothelial migration (extravasation)
What are the steps of phagocytosis?
- Binding
- Engulfment
- Phagosome formation
- Phagolysosome
- Membrane disruption
- Secretion
- Antigen presentation
What are PAMPs?
Pathogen associated molecular patterns= Common features of pathogens that can be detected by the innate immune system.
Name some PAMPs
CpG motifs, Double stranded RNA etc.
What are PRRs?
Pattern recognition receptors= A family of proteins which recognises and binds to a variety of pathogen ligands
Includes TLR, NLR
Give some examples of Cell-associated PRRs?
TLRs, NLRs, Mannose Receptors
What are toll-like receptors?
Receptors found on macrophages, dendritic cells and neutrophils. They recognise and bind to PAMPs. This causes second messengers to cause secretion of inflammatory mediators and stimulate immune cells.
What does TLR4 recognise?
Lipopolysaccharies on gram -ve bacteria
Drives signalling
What do pattern recognition receptors recognise?
PAMPS (pathogen associated molecular patterns)
DAMPS (Damage associated molecular patterns)
What does NOD2 recognise?
Muramyl dipeptide, a breakdown product of peptidoglycan, and this activates inflammatory signalling pathways
What does mannose receptor recognise?
Fungi
What is MHC?
Major histocompatibility complex. Has a major role in initiating T cell responses, and acts as a safety mechanism to prevent the immune system being activated too easily= proteins that mark a cell as self
Describe MHC I
Intracellular, and found on the surface of most cells of the body (Except erythrocytes). Cytotoxic T cells require an antigen to be associated with MHC I proteins before they kill the cell containing the pathogen
Describe MHC II
Extracellular and found mainly on the surface of B cells, macrophages and Dendritic cells. T Helper cells require MCH II proteins before they can help B cells.
Briefly describe neutrophils
Polymorphonuclear leukocyte with 6-12 hr lifespan. Most abundant WBC in blood, and first line cells in acute infection= release chemotaxins and cytokines. Granular.
Briefly describe macrophages
Express CD16- Involved in phagocytosis, with months lifespan. Functions to remove anything foreign or dead. Have lysosomes.
Link between adaptive and innate immunity
Briefly describe eosinophils
Make up 5% of blood, and lifespan of 8-12 days. Granules. Associated with parasitic infection. Neutralises histamine.
Briefly describe Basophils
Make up 2% of blood, with lifespan of 2 days. Known as circulating mast cells. Role in immunity and allergic response= releases histamine
List the cells/ complexes involved in adaptive immunity
- Antigen presenting cells
- Major histocompatibility complex
- T helper cells
- Cytotoxic T cells
- B cells
- Antibodies
What are IgM antibodies role?
1st response to antigen
Can’t cross the placenta
What are IgD antibodies roles?
B cell activation
Can’t cross placenta
What are IgG antibodies roles?
Most common form Crosses placenta (Passive immunity to fetus)
What are IgA antibodies roles?
Secreted from mucous membranes
In colostrum
What are IgE antibodies roles?
Histamine reactions and allergies
What is an antigen?
A molecule that reacts with preformed antibody and specific receptors on T and B cells
What is affinity?
A measure of binding strength between an epitope and an antibody binding site- the higher the affinity the better
What are the functions of the complement pathway?
Lyse microbes directly
Increase chemotaxis
Opsonisation
Briefly describe the mechanism of the complement pathway
Pore-like channels in membrane so water, ions and small molecules enter microbe which disrupts intracellular environment and kills the microbe
What are the three mechanisms of C3 cleavage in the complement?
Classical pathway
Alternative pathway
Lectin pathway
What starts the classical pathway?
Antibody-antigen immune complexes
What starts the alternative pathway?
Foreign surfaces= antigens
What starts the lectin pathway?
Lectin binding to mannose on pathogens surfaces
What cells can act as antigen presenting cells?
Dendritic cells
Also B cells and macrophages
What is major histocompatibility complex formed of?
Proteins that mark a cell as self
Where are T cells formed?
Produced in the bone marrow and mature in the thymus
What is the major role of T cells?
Recognise the antigen displayed by APCs, and produce cytokines
What is the lifespan of a T cell?
hrs-years
What are CD8 cells?
Cytotoxic T cells
Induce apoptosis in infected body cells using perforin. Expresses Fas Ligand which binds to Fas 🡪 apoptosis. Recognise Ag in the context of MHC I.
What are CD4 cells?
T helper cells= help immune response for intracellular pathogens and help B cells make antibodies. Include TH1 and TH2
What are specific roles of Th1 cells?
Cell-mediated immunity. Regulate monocytes and macrophages.
What are the specific roles of Th2 cells?
Humoral immunity. Regulators of eosinophils, basophils, and mast cells. Stimulates B cells.
How do Th1 cells cause B cells to produce antibodies?
- APC presents Ag with MHC II to CD4
- Stimulation with high levels of IL-12 activates naieve cells to Th1
- Th1 goes into secretory lymphoid tissue
- Activated Th1 proliferates
- Th1 cell recognises Ag on infected cell via T cell receptor
- This induces B cell to produce antibodies via IL-2 secretion
What are the roles of treg cells?
Suppresses autoimmunity (Anti inflammatory), and down regulates other T cell subsets via IL-10. Antagonist to Th17 cells.
How are babies protected against diptheria, tetanus, streptococcus, rubella, mumps and polio?
Natural passive immunty by the transfer of maternal antibodies across the placenta in a developing foetus
Give some uses of passive artificial immunisation
- Botulism, tetanus and diptheria= given anti toxin
- Hepatitis, measles and rabies= Given prophylactically after exposure
Briefly describe active immunisation
- Engage innate immune system
- Elicit danger signals that activate the immune system, triggers PAMPs and engage TLR receptors
- Activate specialist APCs
- Engage adaptive immune system= Generate memory T and B cells
Which lasts longer- active or passive immunity?
Active immunity
Why is influenza vaccine repeated annually?
- It is important to maintain high levels of antibody
- Influenza mutates frequently so new vaccines must be given
Why is influenza dangerous?
It has a rapid onset, and infection can be established before immunological memory can be activated
Which vaccines are given via a living whole organism (Attenuated)?
TB (BCG) , Polio sabin, Typhoid, MMR
Which vaccines are given as dead organisms?
Anthrax, cholera, hepatitis A, Influenza, Rabies, Polio Salk
What vaccines are given as toxoids (inactivated endotoxins)?
Diptheria, neurotoxins
What vaccines are given as capsular polysaccharide vaccines?
Pneumococcal disease, salmonella typhi, meningococcal disease
Why may attenuated vaccines be used or not used?
+ Full immune response, only single dose required
- Immunocompromised patients may become infected, vaccine needs to be refrigerated
Why may killed, inactivated pathogen vaccines be used or not used?
+No risk of infection, less critical storage
- Only activates humoral response, booster vaccines
Why may toxoid vaccines be used or not used?
+ Safer as no risk of infection, easier to store
- Less powerful immune response, and booster vaccines needed
What are some pros and cons of passive artificial infection?
+ Immediate protection even in immunocompromised patients
- Short lived, serum sickness
What are the three types of subunit vaccines?
Toxoids, polysaccharides and recombinant vector vaccines
What is an adjuvant?
Any substance that is added to a vaccine to stimulate the immune system ensuring a powerful immune response
Give some examples of adjuvants
Whole killed organisms, taxoids, proteins or chemicals
What are notifiable diseases?
Diseases, infections and conditions specifically listed as notifable under the public health regulations of 1988.
Why are there notifiable diseases?
To detect changes in disease spread, and allows interventions targetted at vulnerable group
It also allows investigation into who may have been exposed.
List some notifiable diseases
MMR diseases Cholera Food poisoning Meningitis Rabies Leprosy SARS TB
How does meningococcal infection present?
Meningitis or septicaemia
What are some complications of meningococcal infection?
Brain abcess, brain damage, seizure disorders, hearing impairment, focal neurological disorders, organ failure, gangrene, death
How is meningococcal infection spread?
Inhaling respiratory secretion from the throat or mouth, or by direct contact (kissing)
What is the treatment of meningococcal infection?
Antibiotic therapy of cefotaxime and ceftriaxone
Who is “at risk” for flu vaccine?
- Those 65 and over
- Certain medical conditions including asthma and diabetes
- Long-star residential care
- Frontline health or social care workers
- Those that are the main carer for someone at risk
What vaccines are given to 8 week old babies?
Infanrix hexa- Hep B, Diptheria, tetnus, polio, pertussis, haemophilius influenza B,
Meningococcal B (Bexsero)
Rotavirus
What vaccines are given to 12 week old babies?
Infanrix hexa booster
Rotavirus booster
Pneumococcal
What vaccines are given at 17 weeks?
Infanrix hexa booster
Bexsero Booster
What vaccines are given at one year?
Haemophilius influenza B and Men C
Pneumococcal booster
MMR
Meningococcal B booster
What vaccines are given at 3 years 4 months?
Diptheria, tetanus, pertussis, and polio boosters
MMR booster
What vaccine is given to boys and girls aged 12-13?
Human papillomavirus
What vaccines are given at 14 years old?
Tetanus, diptheria and polio boosters
Meningococcal groups A, C, W and Y
What vaccine is given at 70 years old?
Shingles
Where are B cells produced?
Produce and mature in the bone marrow