Questions
Passive Immunisation and Immunoglobulins — Questions
Study questions for Passive Immunisation and Immunoglobulins.
Mock Exam mode
Sit this set one question at a time. Multiple-choice questions mark themselves; written questions reveal a tickable mark scheme so you can score your own answer. You get a combined score at the end.
15 questions: 11 MCQ, 4 written.
High prioritySAQDescribe the nature and the indications of palivizumab and nirsevimab. [4]
Model answer
Nature. Both are monoclonal antibodies against the respiratory syncytial virus (RSV) fusion (F) protein, giving passive protection. Palivizumab is given monthly through the RSV season; nirsevimab is engineered for a long half-life, so a single dose covers a whole season.
Indications. Prevention, not treatment, of severe RSV lower-respiratory-tract disease in infants: palivizumab for high-risk infants (prematurity, chronic lung disease, significant congenital heart disease), and nirsevimab for a broader infant population. Neither helps once RSV infection is established.
High prioritySAQName the five immunoglobulin isotypes and give the role and structure of each that is most relevant to antiviral immunity. [8]
Model answer
- IgG: a single Y-shaped monomer; the main serum antibody, neutralising virus and crossing the placenta, and the basis of most passive immunisation.
- IgM: a large pentamer; the first antibody of a primary response and a marker of recent or acute infection.
- IgA: a monomer in blood but a dimer in secretions; the secretory antibody at mucosal surfaces and in breast milk, the key mucosal defence.
- IgE: a single Y-shaped monomer; allergy and antiparasite responses, with only a minor antiviral role.
- IgD: a single Y-shaped monomer; largely a B-cell surface receptor, with little defined antiviral effector role.
- MCQ
A hyperimmune (specific) immunoglobulin is preferred over normal human immunoglobulin when:
- A. Broad antibody against many different agents is needed
- B. The patient has selective IgA deficiency
- C. Only intravenous administration is possible
- D. High-titre antibody against one agent is needed
- E. Long-term replacement therapy is required
Show answer
Correct answer: D
Specific (hyperimmune) immunoglobulin is prepared from high-titre donors to give concentrated antibody against one agent (hepatitis B, varicella-zoster, rabies), used for targeted post-exposure protection. Normal human immunoglobulin gives broad antibody for measles or hepatitis A prophylaxis and for replacement therapy.
The other options do not determine the choice of a hyperimmune product.
- MCQ
A neonate born to an HBsAg-positive mother should receive hepatitis B immunoglobulin:
- A. Only if the baby becomes symptomatic
- B. With the vaccine, within 12 hours of birth
- C. At six weeks with the first hexavalent dose
- D. Instead of the hepatitis B vaccine
- E. Only after confirming the baby is infected
Show answer
Correct answer: B
Hepatitis B immunoglobulin is given with the vaccine as soon as possible after birth (within 12 hours), the combination preventing the great majority of perinatal infections.
It supplements rather than replaces the vaccine, and waiting for symptoms or proven infection would be far too late.
- MCQ
After receiving an immunoglobulin product, a live vaccine such as MMR should be:
- A. Given at the same visit for convenience
- B. Given two weeks earlier than usual
- C. Deferred for several months
- D. Avoided permanently
- E. Replaced with a higher dose
Show answer
Correct answer: C
Passively transferred antibody neutralises live vaccine virus, so live vaccines such as MMR or varicella are deferred for several months after an immunoglobulin product (and immunoglobulin is withheld for about two weeks after a live vaccine).
They are not given together, abandoned, or dose-adjusted.
- MCQ
Compared with a polyclonal immunoglobulin, a monoclonal antibody is:
- A. Directed against many viral epitopes simultaneously
- B. Pooled from thousands of donors
- C. A single specificity of standardised potency
- D. Unable to be produced at scale
- E. Entirely free of escape-mutant risk
Show answer
Correct answer: C
A monoclonal antibody is a single defined specificity, made recombinantly to a standardised potency and scalable supply. A polyclonal product is the donor-pooled, multi-epitope alternative.
Monoclonals can be made at scale, and a changing virus can escape their single epitope.
- MCQ
How is the risk of transmitting blood-borne viruses by immunoglobulin products minimised?
- A. By donor screening and pathogen-inactivation steps
- B. By giving the smallest possible dose
- C. By storing the product deep-frozen
- D. By using only a single donor per batch
- E. By irradiating each immunoglobulin batch before use
Show answer
Correct answer: A
Donor screening combined with deliberate pathogen removal and inactivation (solvent-detergent treatment, low-pH incubation and nanofiltration) makes modern immunoglobulin products very safe.
Dose size, freezing, single-donor sourcing and irradiation are not how this safety is achieved; pooling many donors is in fact standard.
- MCQ
Passive antibody is most effective when given:
- A. Before or very soon after exposure
- B. Once symptoms are established
- C. Only in severe, late disease
- D. Several weeks after recovery
- E. At the same time as a live vaccine
Show answer
Correct answer: A
Passive antibody works best before exposure, or early after it and before symptoms, and does little once disease is established, because the virus has by then spread beyond circulating antibody. Lassa immune plasma, life-saving within the first few days but not later, is the clear example.
The other timings give little or no benefit.
- MCQ
Rabies post-exposure prophylaxis combines vaccine and rabies immunoglobulin because:
- A. Immunoglobulin gives immediate cover while active immunity develops
- B. Immunoglobulin makes the vaccine produce a much longer-lasting response
- C. Using two products lowers the overall cost of treatment
- D. The rabies vaccine on its own cannot prevent the disease
- E. Immunoglobulin removes the need for thorough wound cleaning
Show answer
Correct answer: A
The immunoglobulin provides instant passive protection in the first days, bridging the gap until the vaccine generates the patient’s own lasting antibody. It is infiltrated into the wound and gives no added benefit once the vaccine response has begun.
It does not prolong the vaccine, lower cost, or replace wound care.
- MCQ
Rituximab is used in EBV-driven post-transplant lymphoproliferative disorder (PTLD) because it:
- A. Neutralises circulating EBV particles
- B. Replaces missing antibody in the patient
- C. Boosts the patient's own EBV immunity
- D. Provides passive neutralising antibody against EBV
- E. Depletes the proliferating CD20-positive B cells
Show answer
Correct answer: E
Rituximab is an anti-CD20 antibody that depletes the proliferating B cells of PTLD, acting on the host cells rather than on the virus. It is a host-directed therapeutic monoclonal, not a passive antiviral antibody.
It does not neutralise EBV, replace antibody, or boost antiviral immunity.
- MCQ
The duration of protection from a standard immunoglobulin reflects the half- life of IgG, which is approximately:
- A. 1 day
- B. 3 days
- C. 3 weeks
- D. 6 months
- E. 5 years
Show answer
Correct answer: C
IgG has a half-life of about three weeks, so a polyclonal immunoglobulin protects for weeks to a few months; Fc-engineered monoclonals extend this to around three months.
The other intervals misstate how long IgG persists.
- MCQ
Which immunoglobulin class crosses the placenta to give the newborn passive protection?
- A. IgA
- B. IgG
- C. IgM
- D. IgE
- E. IgD
Show answer
Correct answer: B
IgG is the only immunoglobulin actively transported across the placenta, mainly in the third trimester, so the newborn begins life with antibody mirroring the mother’s. It wanes over the first six months.
Secretory IgA is supplied by breast milk; IgM, IgE and IgD do not cross the placenta.
- MCQ
Which patients are at particular risk of anaphylaxis to immunoglobulin products?
- A. Those with prior hepatitis B vaccination
- B. Those with a high serum IgG level
- C. Pregnant women in the first trimester
- D. Children under one year of age
- E. Those with selective IgA deficiency
Show answer
Correct answer: E
People with selective IgA deficiency can form anti-IgA antibodies and react anaphylactically to immunoglobulin products, so this history must be sought.
The other groups are not at specific risk on these grounds.
SAQOutline how immunoglobulin products are made safe from blood-borne pathogens. [3]
Model answer
- Donor selection and screening of the source plasma for blood-borne viruses.
- Pathogen removal and inactivation during fractionation: solvent-detergent treatment, pasteurisation, low-pH incubation and nanofiltration.
- Together these give modern products an excellent safety record; historical transmission of hepatitis by early antibody preparations is what drove the safeguards.
SAQWhen and how is immunoglobulin replacement therapy used in immunodeficiency? [3]
Model answer
- Indication: primary antibody deficiencies (for example X-linked agammaglobulinaemia and common variable immunodeficiency), and some secondary antibody deficiencies, where the patient cannot make protective antibody.
- How: regular intravenous or subcutaneous immunoglobulin every few weeks, supplying a broad antibody repertoire.
- Aim: maintain a protective trough level and prevent recurrent infection; this is lifelong therapy.