Clinical Immunology MCQs

Clinical Immunology

Clinical immunology is the branch of medicine that focuses on the study of the immune system and its disorders. It deals with the diagnosis, treatment, and management of immune-mediated diseases such as allergies, autoimmune diseases, and transplant rejection.

With the increasing incidence of these diseases, clinical immunology plays a crucial role in modern medicine and has a significant impact on patient health and well-being. If you want to test your knowledge, then why not try our varied MCQ test? It is a fun and interactive way to challenge yourself and expand your understanding of clinical immunology. Just click to reveal the answer.

CD Acronym

What does CD stand for in immunology (e.g. CD4 Tcell._)

  • Control Data
  • Chemical Dependency
  • Cluster Designation
  • Cognitive Disabilities
  • Counter-Drug
  • Communication Disorder

Cluster Designation

CD stands for cluster designation and is the widely used nomenclature to identify cell surface antigens. For example CD20 positive B cells are targeted by the monoclonal antibody Rituximab when treating lymphoma and rheumatoid arthritis.

Wegener’s granulomatosis

What proportion of patients with Wegener’s granulomatosis will have a positive ANCA?

  • 0%
  • <20%
  • 50%
  • >80%


WG is characterised by

  • Nasal symptoms
  • Fixed pulmonary infiltrates
  • Systemic vasculitis (nephritis/ pneumonitis etc)
  • Positive ANCA (in >80% of cases)

T Cell Role

What is the role of CD4+ T cells?

  • “Cytotoxic”
  • “Supressor
  • “Helper”
  • Secrete immunoglobulin
  • None of the answers listed here


The CD 4 cell surface marker is expressed by most “helper” cells which play a role in the up-regulation of the immune response.

The CD8 surface marker is expressed by “cytotoxic” T cells,

Polyarteritis Nodosa

What proportion of patients with Polyarteritis Nodosa (PAN) will have a positive ANCA?

  • 0%
  • <20%
  • 50%
  • >80%


PAN is classically ANCA negative and is a small/medium sized vessel vasculitis.

The ACR Criteria (American college of Rheumatology) include the following:

Weight loss
Livedo reticularis
Testicular pain (classical in PAN)
Muscle pain/weakness
Renal Failure
Intercurrant Hepatitis B virus infection
Angiographic dilatation of arteries (esp mesenteric)
Classical vasculitic appearances on biopsy


Where is histamine predominantly released from?

  • Basophils
  • Neutrophils
  • Eosinophils
  • Macrophage
  • Natural Killer Cells


Histamine is predominantly released from mast cells and basophils and acts via cell surface receptors to produce the characteristic symptoms seen in allergy

  • smooth muscle contraction e.g. bronchospasm
  • increased vascular permeability e.g. oedema
  • Increased glandular secretions e.g. rhinitis


A 18 year old with a nut allergy presents to hospital 5 hours after a meal.

She has mild tingling around her face.

Her lips appear slightly swollen

Her observations are as follows:

Sats 99% Air
RR 16
P 82
BM 6.5
CVS: Normal Heart sounds
Respiratory: No wheeze.

Her past medical history includes a history of anaphylaxis 10 minutes after exposure to a peanut which caused cardiovascular collapse and an admission to intensive care.

What is the most likely diagnosis here?

  • Anaphylaxis
  • Allergic reaction
  • Hereditary Angio-oedema
  • Superior vena cava obstruction
  • None of the above reactions

Allergic reaction

Although close observation is essential here and some anaphylactic reactions can be biphasic, the clinical presentation here dfoes not have the features of a true anaphylactic reaction i.e.

  • Bronchospasm
  • Airway oedema
  • Rash
  • Shock

This leaves an allergic reaction as the most likely cause.

Antibody mediator

Which antibody is the mediator of anaphylaxis?

  • IgA
  • IgE
  • IgG
  • IgM
  • None of the antibodies listed here


IgE is the mediator of anaphylaxis in response to an antigen that the patient has “memory” to i.e. has been prior sensitised to this antigen.

ANA titre

A medical student believes he has condition X. He’s aware of an antibody to the condition and asks for an antibody test.

The test is reported as follows:

ANA positive at :1 in X

Which of the following ANA positivity would indicate the most likely chance of an underlying autoimmune disease?

  • ANA positive titre 1 in 2
  • ANA positive titre 1 in 16
  • ANA positive titre 1 in 32
  • ANA positive titre 1 in 64
  • ANA positive titre 1 in 128

ANA positive titre 1 in 128

Answer follows the next question in the clinical immunology section, but the higher the number, the more significant the result.

Continued from previous question.

The test is reported as follows:
ANA positive at :1 in 128

What does this result mean?

  • ANA positive titre 1 in 2
  • ANA positive titre 1 in 16
  • ANA positive titre 1 in 32
  • ANA positive titre 1 in 64
  • ANA positive titre 1 in 128

ANA positive titre 1 in 128

The answer is the number of times the sample can be diluted and the antibody still identifiable by immunofluorescence.

1 in 2 – serum dilute to half concentration
1 in 4: serum diluted to 1 part in 4
Etc etc.

Strongly positive results (e.g. 1 in 2400) are more likely to indicate disease.