Immune modulating therapies (1) Flashcards
How can the immune response be boosted?
- Vaccination
- Replacement of missing components
- Cytokine therapy
- Blocking immune checkpoints
Describe the following about the adaptive immune response
- Adaptive immune response cells
- Wide repertoire of antigen receptors
- Specificity
- Adaptive Immune Response
* B cells and T cells - Wide repertoire of antigen receptors
- Receptor repertoire is not entirely genetically encoded
- Genes for segments of receptors are rearranged and nucleic acids deleted/added at the sites of rearrangement almost randomly
- Potential to create in order of 1011 to 1012 receptors
- Autoreactive cells are likely to be generated
- Mechanisms must exist to delete or tolerise these autoreactive cells
- Exquisite specificity
* able to discriminate between very small differences in molecular structure
What are antigen presenting cells (APC)?
- APCs are cells that can present peptides to T lymphocytes to initiate an acquired immune response
- These cells include:
- Dendritic cell
- Macrophage - include Langerhans cells, mesangial cels, Kupffer cells (liver), osteoclasts, microglia etc.
- B lymphocyte
Describe clonal expansion following exposure to antigen in the adaptive immune system
Clonal expansion following exposure to antigen:
- T cells with appropriate specificity will proliferate and differentiate into effector cells (cytokine secreting, cytotoxic)
- B cells with appropriate specificity will proliferate and
- differentiate to T cell independent (IgM) (memory and) plasma cells
- undergo germinal centre reaction and differentiate to T cell dependent IgG/A/E(M) memory and plasma cells
There is then immunological memory - following infection, residual pool of specific cells with enhanced capacity to respond if re-infection occurs
Describe the CD8 T cell response to an infection

Describe CD4 T cell response to infection

What are the different CD4 T cell subsets?
- Help CD8 T cells and macrophages
- Help neutrophil recruitment
- IL-10/TGF beta expressing
- CD25+ Foxp3+
- Follicular helper T cells
- Helper T cells

Describe T cell memory, how long it lasts and action
Longevity
- Memory T cells are maintained for a long time without antigen by continual low-level proliferation in response to cytokines
Different pattern of expression of cell surface proteins involved in chemotaxis cell adhesion
- These allow memory cells to access non-lymphoid tissues, the sites of microbial entry.
Rapid, robust response to subsequent antigen exposure
- There are more memory cells
- These cells are more easily activated than naïve cells
Describe the B cell response to an infection

Describe B cell memory - how lomg it lasts, action etc.
Longevity
- Long lived memory B cells and plasma cells
Rapid, robust response to subsequent antigen exposure
- There are more memory cells
- These cells are more easily activated than naïve cells
Pre-formed antibody
- Circulating high affinity IgG antibodies
What do we want from a vaccine?
- Generate protective, long-lasting immune response
- No adverse reactions
- Single shot
- Easy storage
What part of the influenza virus causes the infection?
- Hemagglutinin (HA) is the receptor-binding and membrane fusion glycoprotein of influenza virus and the target for infectivity-neutralizing antibodies.
In influenza CD8 T cells controls the virus load and it is the antibody which provides a protective response
Describe the haemagglutination inhibition assay
Detection of virus specific antobodies
- Sialic acid receptors on RBC bind to haemagluttin of influenza virus to ‘haemagluttinate’
Reaction inhibited by antibodies to haemagluttin
Describe how the mantoux test is done
- Inject 0.1 ml of 5 tuberculin units of liquid tuberculin intradermally.
- The tuberculin used in the Mantoux skin test is also known as purified protein derivative, or PPD.
- The patient’s arm is examined 48 to 72 hours after the tuberculin is injected.
- The reaction is an area of induration (swelling that can be felt) around the site of the injection.
- What is the BCG?
- What does the BCG do?
- What response is important?
- BCG is an attenuated, strain of bovine tuberculosis
- Protects against primary inection, as well as progression to active TB
- T cell response is important in protection
Describe the maintenance of responses for the:
- Influenza vaccine
- TB vaccine
- Influenza
Antibody protection begins within 7 days after immunization. Protection can last for approximately 6 months or longer in the general population.
- TB
Protection in the UK after BCG lasts about 10-15 years.
What the types of vaccines?
- Live vaccines
- Inactivated/Component/Conjugate vaccines
- Adjuvants to increase immunogenicity
- DNA vaccines
- Dendritic cell vaccines
What is a live attenuated vaccine? Examples?
- A live attenuated vaccines use a live organism to induce an immune response
- Organism is modified, (attenuated) to limit pathogenesis
- Examples:
- MMR
- BCG
- Yellow fever
- What are the advantages of live vaccines?
- What are the problems with live vaccines?
- Pros
- Establishes infection – ideally mild symptoms
- Raises broad immune response to multiple antigens – more likely to protect against different strains
- Activates all phases of immune system. T cells, B cells – with local IgA, humoral IgG
- Often confer lifelong immunity after one dose
- Cons
- Storage problems
- Possible reversion to virulence (recombination, mutation).
- Vaccine associated paralytic poliomyelitis (VAPP, ca. 1: 750,000 recipients)
- Spread to contacts
- Spread to contacts of vaccinee who have not consented to be vaccinated
- Spread to immunosuppressed/immunodeficient patients
Describe the different inactivated/component vaccines
Inactivated Vaccines
- Influenza, Cholera, Bubonic plague, Polio (Salk), Hepatitis A, Pertussis, Rabies.
Toxoids (inactivated toxins)
- Diphtheria, Tetanus.
Component/subunit vaccines
- Hepatitis B (HbS antigen), HPV (capsid), Influenza (haemagglutinin, neuraminidase).
What are the advantages and disadvantages of inactivated/component vaccines?
Advantages:
- No mutation or reversion
- Can be used with immunodeficient patients
- Can lead to elimination of wild type virus from the community
- Storage easier
- Lower cost
Disadvantages:
- Often do not follow normal route of infection
- Some components have poor immunogenicity
- May need multiple injections
- May require conjugate protein carrier or adjuvants to enhance immunogenicity
Describe conjugate vaccines, and examples
Conjugate vaccines:
- Polysaccharide plus protein carrier
- Polysaccharide alone induces a T cell independent B cell response – transient
- Addition of protein carrier promotes T cell immunity which enhances the B cell/antibody response
e.g.
- Haemophilus Influenzae B
- Meningococcus
- Pneumococcus
Describe adjuvant vaccines and some examples
- Adjuvant increases the immune response without altering its specificity
- Mimic action of PAMPs (pathogen associated molecular patterns) on TLR (toll-like receptors) and other PRR (pattern recognition receptors)
Examples:
- Aluminium salts (humans)
- Lipids – monophosphoryl lipid A (humans)
- Oils -Freund’s adjuvant (animals)
- ISCOMS
- CpG DNA
Describe the actions of aluminum salts as an adjuvant therapy in humans
Which vaccines is it used in?
- Primary adjuvant utilized in humans – safe and effective
- Mechanism not fully elucidated
- Alum may allow antigens to be slowly released, prolonging the immune stimulation
- Alums induce a mild inflammatory reaction that will then promote development of adaptive immune response
- Alum activates Gr1+ IL4+ eosinophils to help prime naïve B cells leading to antibody response
Used in many vaccines including hepatitis A, hepatitis B, Hib
