Imm - Immune modulation

Question 1

What are the immune modulatory methods of boosting the immune response

Answer 1

Vaccination
Replacement of missing components
Blocking immune checkpoints
Cytokine therapy

Question 2

What is the immune pathophysiology behind the vaccine functioning

Answer 2

1. APCs present peptides to T cells (Cd4/8)
2. Clonal expansion of appropriate T cells
   - CD4 → release cytokines to activate B cells/others (slightly less expansion)
   - CD8 → kills infected cells
3. Effector T cells die by apoptosis OR suvive as memory cells
4. B cells differentiate to:
   - T cell independent (IgM) memory cells OR
   - T cell dependent (IgG/A/E) plasma cells

Question 3

Give examples of antigen presenting cells

Answer 3

Dendritic cells
Macrophages (Langerhans cells, mesangial cells, Kupffer cells, osteoclasts, microglia, etc.)
B-lymphocytes

Question 4

What are the advantages of memory cells

Answer 4

Longevity - persisting without antigen (low level proliferation in response to cytokines)
Different cell surface proteins and access to non-lymphoid tissues
Rapid- robust response to subsequent antigen exposure
Pre-formed, high affinity IgG antibodies present (B cells)

Question 5

What are the ideal features of a vaccine

Answer 5

1. Generates immunological memory
2. Practical - single injection, easy storage, inexpensive
3. No adverse effects

Question 6

What are the types of vaccine

Answer 6

Live attenuated vaccines
Inactivated/component vaccines (inc. conjugates and adjuvants to increase immunogenicity
DNA vaccines
Dendritic cell vaccines

Question 7

What are live attenuated vaccines and give examples

Answer 7

The organism is modified to limit pathogenesis

MMR
BCG
Yellow fever
Typhoid
Polio (Sabin - oral)
Vaccinia
Influenza nasal spray

Question 8

What are the advantages and disadvantages of live attenuated vaccines

Answer 8

Establishes infections (ideally mild symptoms) Raises broad immune response to multiple antigens/strains
Activates all phases of immune system (T cells, B cells – local IgA, humoral IgG, etc.)
Often confer life-long immunity after one dose

Storage problems
Possible reversion to virulence
Spread to contacts (i.e. spread to immunocompromised/immunosuppressed)
Risk of paralytic poliomyelitis (VAPP)

Question 9

What are inactivated/component/toxoid vaccines and give examples

Answer 9

Inactivated vaccines = influenza, cholera, polio (Salk - IM), HAV, Pertussis, Rabies

Component/subunit vaccines = HbS antigen, HPV (capsid), influenza

Toxoids (inactivated toxins) = diphtheria, tetanus

Question 10

What are the advantages and disadvantages of inactivated/component/toxoid vaccines

Answer 10

No mutation or reversion
Can be used in immunodeficient patients
Easier storage and lower cost

Often do not follow normal route of infection
May have poor immunogenicity
May need multiple injections
May require conjugates or adjuvants

Question 11

What are conjugate vaccines and give examples

Answer 11

polysaccharide + protein carrier:
Polysaccharide → T cell-independent B cell response (transient)
Protein → T-cell dependent B cell response (long-term)

HiB, meningococcus, pneumococcus (NHS), tetanus

Question 12

What are RNA/DNA vaccines and give examples

Answer 12

Plasmid (vector) containing a pathogenic gene of choice is inserted into a muscle cell → Plasmid does NOT replicate but the gene encodes protein that is presented at the cell surface of the host cell (looks like infected cell)
Mimics the normal action of a virally infected cell and it stimulates T cell responses

COVID:
- mRNA: SARS-CoV-2
- adenoviral vectors: AstraZeneca

Question 13

What are the advantages and disadvantages of RNA/DNA vaccines

Answer 13

Mimics virus cell
May be used to develop a cancer vaccine

Plasmid may integrate into the host DNA → autoimmune disease

Question 14

What are adjuvants and give examples

Answer 14

increases the immune response without altering its specificity
Mimic the action of PAMPs on TLR and other PRRs
OR slows the release of the antigen to ensure a steady stream → prolonged immune response

Aluminium salts (humans)
Lipids (monophosphoryl lipid A; humans)
Oils (Freund’s adjuvant; animals)
ISCOMS
CpG DNA

Question 15

Describe aluminium salt adjuncts

Answer 15

(ALUM)
most common, the primary adjuvant used in humans
Slows the release of the antigen to ensure a steady stream → prolonged immune response
Antigens are adsorbed to alum → slowly releases antigen → prolonged antigenic stimulation
Activates Gr1+ cells → IL-4 → helps to prime naive B cells

Question 16

Describe CpG adjuvants

Answer 16

Stimulatory adjuvant, mimics PAMPs on TLR/PRRs
Unmethylated DNA rich in CpG (cytosine, phosphate, guanine) → activates TLRs (9) on APCs → stimulates expression of costimulatory molecules

Question 17

Describe Complete Freund’s adjuvants

Answer 17

Water-in-oil emulsion containing mycobacterial cell wall components.
Mainly for animals, painful in humans (not used clinically)

Question 18

Describe ISCOMS (Immune Stimulating Complex) adjuvants

Answer 18

Experimental
Multimeric antigen with adjuvant built in.
Cell-mediated immune response and humoral response
With saponin results in strong serum antibody response.

Question 19

What are dendritic cell vaccines and give an exmaple

Answer 19

Used against tumours where dendritic cell function may be compromised
Load the patient’s dendritic cells with a tumour antigen → re-introduce them to the patient → boost response against tumour antigens
Requires antigens specific to the tumour and distinct from normal cells

E.g. Sipuleucel-T (Provenge) – prostate ca.

Question 20

Describe the immune response to influenza

Answer 20

Antibodies are responsible for protection, CD8 T cells control viral load
Haemagglutinin (HA) is a fusion glycoprotein on the membrane → allows for detection via. a haemagglutinin inhibition assay
Antibody protection begins 7 days after vaccine and protection can last for around 6 months

Question 21

Describe haemagglutinin inhibition assays

Answer 21

Normal red cells → clump to form a red spot
Adding influenza → HA makes cells stick together → diffuse colouration across the well
Add serum of someone with lots of ABs against HA → inhibits HA from making cells stick → cells clump at the bottom

This can be done using lots of wells and different dilutions → Higher dilutions with an inhibitory effect → greater level of antibodies the patient has against HA
The higher the antibody level the lower the likelihood of infection

Question 22

Describe the tuberculosis vaccine

Answer 22

BCG
Attenuated strain of bovine tuberculosis
Provides some protection against primary infection, mainly progression from latent → active
T cell response important
Lasts 10-15 years

Question 23

Describe Mantoux testing

Answer 23

? previous exposure to TB:

1. Inject a small amount of liquid tuberculin (purified protein derivative / PPD) intradermally
2. Area of injection is examined 48-72 hours after tuberculin injection
3. The reaction is an area of swelling around the injection site
4. Positive reaction wheal:
   - >5mm (high-risk – i.e. immunocompromised, living with someone with TB)
   - >10mm (medium-risk – i.e. healthcare workers)
   - >15mm (low-risk)

Question 24

What vaccines are given in adulthood

Answer 24

50yrs onwards: flu annually
65 yrs: Pneumococcal (PPV)
70 yrs: Shingles
Pregnancy (any age): Flu during appropriate season, DTaP/IPV from 16/40
gestation, pertussis from 16-32

Question 25

What are the methods of replacing missing compounds

Answer 25

Haematopoietic stem cell transplantation
Antibody replacement
Specific immunoglobulin
Adoptive cell transfer (ACT)

Question 26

What are the indications for Haematopoietic stem cell transplantation

Answer 26

Offers potential for complete and permanent cure:

Life-threatening immunodeficiency (e.g. SCID, leucocyte adhesion defect)
Haematological malignancy

Question 27

Describe antibody replacement and what are the indications

Answer 27

Ig can be replaced with human normal Ig, prepared from pools of >1000 donors
Contains pre-formed IgG

Primary antibody deficiency
- Bruton’s X-linked hypogammaglobulinemia
- X-linked hyper-IgM syndrome
- Common variable immunodeficiency
Secondary antibody deficiency
- Haematological malignancies (CLL, MM)
- After bone marrow transplantation

Question 28

Describe specific immunoglobulin donation and give examples

Answer 28

AKA passive immunisation
Directly administering pre-formed antibodies/immunoglobulins
Lasts for 3 weeks

HNIG (Human Normal Ig) – Hep A and Measles
HBIG (Hep B) – Hep B (needle stick, sexual contact)
HRIG (Human Rabies) – Rabies (around bites)
VZIG (Varicella Zoster) – Varicella (pregnant <20 weeks or immunosuppressed)
Paviluzimab – monoclonal antibody for RSV

Question 29

What are the types of adoptive T cells transfer

Answer 29

ViS-T: Virus specific T cell therapy
TIL-T: Tumour infiltrating T cells
CAR-T: Chimeric antigen receptor T cells
TCR

Question 30

Describe ViS-T/Virus specific T cell therapy

Answer 30

Indication: prevents development form EBV (in immunosuppressed) → B cell lymphoproliferative
Allogenic (donor) or autologous (pt) cells harvested and stimulated with EBV/antigen
→ expansion of EBV-specific T effector cells → reinfusion into patient

Question 31

Describe TIL-T/Tumour infiltrating T cells and what are the indications

Answer 31

1. Tumour is removed form the patient
2. T cells in the tumour is stimulated with cytokines (IL2)
3. T cells develop a response against the tumour
4. Select and expand tumour infiltrating lymphocytes and reinfuse

Head & neck SCC, melanoma, lung and gynae ca.

Question 32

Describe TCR adoptive T cell transfer

Answer 32

T cells engineered to express receptors specific to tumour antigens

Question 33

Describe CAR-T cell therapy and what are the indications

Answer 33

Similar to TCR, but chimeric receptors also targets CD19 → greater immune response to tumour
1. T cells taken form the patient
2. Vector used to insert gene fragments into the T cells
- TCR → gene specific to TCR → recognises MHC PRESENTED peptides
- CAR therapy → chimeric receptors (B and T) → also recognises cell surface CD markers (CD19) and tumour antigens (Non-MHC)

ALL and NHL

Question 34

Describe cytokine therapy and give examples

Answer 34

Aims to boost immune response to cancer and some pathogens
IL-2: Increase T cell response and cloncal expansion → renal Ca
Interferon alpha: antiviral → hep B and C, Kaposi sarcoma, hairy cell leukaemia, CML, melanoma, Bechets
Interferon beta → relapsing remitting MS
Interferon gamma: increases macrophage function → chronic granulomatous disease

Question 35

What are the indications for immune checkpoint blockade and what are examples

Answer 35

Indications: advanced melanoma, metastatic renal ca.
Ipilimumab: melanoma
Pembrolizumab and Nivolumab: advanced melanoma

Question 36

What is the MOA for Ipilimumab

Answer 36

Blocks immune checkpoints

CTLA4 and CD28 both expressed by T cells and both recognise the same antigens on APCs (CD80 and CD86)
CD28 + APC CD80/CD86 → transmit a stimulatory signal
CTLA4 + APC CD80/CD86 → transmit an inhibitory signal

Ab specific to CTL-A4 → binds to CTLA4 → all interactions of CD80/86 occurs through CD28 → boosting of the T cell response

Question 37

What is the MOA of Pembrolizumab and Nivolumab

Answer 37

Monoclonal antibody specific for PD-1 (programmed death receptor)
PD-1 is found on Treg cells → binds to PD-L1/2 on APCs/tumour cells → t cell inactivation and death
Blocking PD-1 → T cells remain active and kills tumour cells

Question 38

What are the immune modulatory methods of suppressing the immune response

Answer 38

Steroids
Anti-proliferative agents
Plasmapheresis
Inhibitors of cell signalling
Agents directed at cell surface antigens
Agents directed at cytokines

Question 39

Describe how steroids suppress the immune response

Answer 39

Prostaglandin reduction: inhibits phospholipase A2 (usually phospholipid →PA2→ arachidonic acid →COX→ prostaglandins + leukotrienes (pro-inflammatory)

Phagocytes: Reduced adhesion molecule expression and blocked chemokines → reduced chemotaxis to inflamed tissue, reduced phagocytosis and reduced release of proteolytic enzymes

Lymphocyte dysfunction: lymphopaenia due to sequestration (CD4>CD8>B), blocks cytokine gene expression, decreased Ab production, apoptosis

Question 40

What are the side effects of corticosteroids

Answer 40

Metabolic (Cushing’s Syndrome): Central obesity, Moon face, Diabetes, lipid disorders, osteoporosis, hirsutism, adrenal suppression
Others: Cataracts, glaucoma, peptic ulceration, pancreatitis, avascular necrosis
Immunosuppression

Question 41

Give examples of anti-proliferative agents and what is the MOA

Answer 41

Inhibits lymphocyte proliferation by inhibiting DNA synthesis → rapid turnover cells are most affected

Cyclophosphamide
Mycophenolate
Azathioprine

Question 42

What is the MOA for cyclophosphamide and what is it used for

Answer 42

Alkylates guanine on DNA → damages DNA and prevents replication
B cells > T cells

Indications: connective tissue disease, vasculitis with organ involvement (GPA, SLE), cancer

Question 43

What are the side effects of cyclophosphamide

Answer 43

Toxic to proliferating cells (bone marrow suppression, sterility (mainly in males), hair loss)
Haemorrhagic cystitis (toxic metabolite (acrolein) is excreted in the urine)
Malignancy (bladder cancer, haematological malignancies, non-melanoma skin cancer)
Teratogenic
Infection (e.g. Pneumocystis jirovecii / PCP pneumonia)

Question 44

What is the MOA of azathioprine and what is it used for

Answer 44

Metabolised by the liver → 6-mercaptopurine (purine analogue) → blocks de novo purine synthesis (A and G) → prevents DNA replication
T cells > B cells

Used for transplantation, auto-immune disease and auto-inflammatory disease (IBD, Crohn’s)

Question 45

What are the side effects of azathioprine use

Answer 45

Bone marrow suppression (1 in 300 particularly vulnerable; check TPMT activity):
- Thiopurine methyl transferase (TPMT) polymorphisms → Unable to metabolise azathioprine (CHECK TPMT ACTIVITY or gene variants before treatment is started)
Hepatotoxicity
Infection (less common than with cyclophosphamide)

Question 46

What is the MOA of mycophenolate mofetil and what is it used for

Answer 46

Blocks de novo guanosine nucleotide synthesis → prevents DNA replication
T cell > B cell

Transplantation, auto-immune disease, vasculitis

Question 47

What are the side effects of mycophenolate mofetil

Answer 47

Bone marrow suppression (rapid turnover cells particularly vulnerable)
Teratogenic
Infection (herpes virus reactivation, progressive multifocal leukoencephalopathy / JC virus)

Question 48

Describe plasmapharesis and what are the indications and the issues with this method

Answer 48

Removal of pathogenic antibodies from the plasma
Pt blood passed through a separator → Abs removes → cells and plasma reinfused

Goodpasture’s syndrome (anti-GBM)
Severe acute myasthenia gravis (anti-ACh-R)
Severe transplant rejection (antibodies against donor HLA)

Problem: rebound Ab production (plasma cells still present) → can give anti-proliferative agents at the same time to combat

Question 49

Give examples of inhibitors of cell signalling

Answer 49

Calcineurin (ciclosporin, tacrolimus)
mTOR inhibitors e.g. sirolimus
JAK (tofacitinib)
PDE4 (apremilast)

Question 50

Describe calcineurin inhibitors

Answer 50

Inhibits calcineurin → prevents T cell signalling → blocks IL2 production → reduced activation of T cells AFTER APC interaction → reduced clonal expansion and proliferation

Question 51

What are the side effects of calcineurin inhibitors

Answer 51

Nephrotoxicity (ciclosporin = tacrolimus)
HTN (ciclosporin = tacrolimus)
Neurotoxic (ciclosporin = tacrolimus)
Diabetogenic (ciclosporin < tacrolimus)
Dysmorphic features (ciclosporin): Hirsutism, Gingival hypertrophy

Question 52

Describe mTOR inhibitors and what is it used for

Answer 52

Inhibit T cell proliferation and function
Used in transplantation

Question 53

Describe JAK inhibitors and what are they used for

Answer 53

Tofacitinib (JAK 1 and 3) or ruxolotinib (JAK 2)
Interferes with JAK-STAT signalling (important in transducing the signals from cytokine binding)
Influences gene transcription
Inhibits the production of inflammatory molecules

Indication = rheumatoid or psoriatic arthritis

Question 54

Describe PDE4 (Phosphodiesterase 4) inhibitors and what are they used for

Answer 54

Apremilast
Increases cAMP → activates protein kinase A (PKA) → prevents activation of transcription factors → reduced cytokine production

Indication = psoriasis or psoriatic arthritis

Question 55

Agents directed against cell surface antigens: What are the following drugs directed against and give one use:
Basiliximab
Abatacept
Rituximab
Vedolizumab
Natalizumab
Tocilizumab
Muromonab-CD3
Daclizumab
Efalizumab
Alemtuzumab (campath)

Answer 55

Basiliximab: anti-CD25 (no T prolif) - prophylaxis for allograft rejection
Abatacept: CTLA4 Ig (binds APCs → reduced T cell activation) → RhA
Rituximab: Anti-CD20 (depletes mature Bcellls) → Lymphoma, RhA
Vedolizumab: Anti-alpha-4-beta-7 integrin (cell migration) → IBD
Natalizumab (anti-alpha-4-beta-1 integrin (leukocyte arrest, cell migration) → MS, Crohn’s
Tocilizumab: anti-IL-6 (reduced macrophage) → Castleman’s, RhA
Muromonab-CD3: blocks CD3 on T cells → active allograft rejection
Daclizumab: IL-2 receptor Ab for CD25 → prophylaxis for organ transplant rejection
Efalizumab: anti-CDIIa (no T cell migration)
Alemtuzumab (campath): MA for CD52 (lymphocyte depletion): CLL< MS

Question 56

Agents directed at cytokines: what are the following agents directed at and give an indication for each:
Infliximab
Adalimumab
Cerolizumab
Golimumab
Etanercept
Ustekinumab
Guselkumab
Secukinumab
Denosumab
Tocilizumab
Sarilumab
IL-1 blockade
IL-4/5/13 blockade

Answer 56

Infliximab: anti-TNFalpha → RhA, ankspond, psoriasis
Adalimumab: anti-TNFalpha (“)
Cerolizumab: anti-TNFalpha (“)
Golimumab: anti-TNFalpha(“)
Etanercept: anti-TNFalpha/beta (“)
Ustekinumab: anti-IL12 and IL-23 (psoriasis, PsorA)
Guselkumab: anti-IL-23: (“)
Secukinumab: Anti IL-17A (“)
Denosumab: anti-RANK ligand (osteoporosis, MM)
Tocilizumab: Anti-IL6 (RhA, Castleman’s)
Sarilumab: Anti-IL6 (RhA, Castleman’s)
IL-1 blockade (Familial Mediterranean, gout)
IL-4/5/13 blockade (eczema, asthma)

Question 57

What are the side effects of biologics

Answer 57

Infusion reactions:
- Urticaria, hypotension, tachycardia, wheeze – IgE mediated
- Headaches, fevers, myalgias – not classical type I hypersensitivity
- Cytokine storm

Injection site reactions:
- Peak reaction at ~48 hours
- May also occur at previous injection sites (recall reactions)
- Mixed cellular infiltrates, often with CD8 T cells
- Not generally IgE or immune complexes

Acute infection (often 2x)

Chronic infection (TB, HBV, HCV, HIV, JC virus)

Malignancy:
- Lymphoma (EBV)
- Non-melanoma skin cancers (HPV)
- Melanoma (more in those treated with TNFa inhibitors)

Autoimmunity (i.e. SLE, anti-phospholipid syndrome, vasculitis, ILD, sarcoid, uveitis, AI hepatitis, demyelination)