You are investigating Charlie, a 7 month old boy who has presented with recurrent otitis media and chest infections. Chest x-ray shows widespread pulmonary infiltrates in a 'ground-glass' pattern, and subsequent sputum samples culture Pneumocystis jirovecii. As part of the work-up for suspected immunodeficiency, you request an extended lymphocyte panel, which shows that Charlie has no B, T, or NK lymphocytes (B-T-NK-). Which immunodeficiency is most consistent with the immunophenotype above?

A. Adenosine deaminase (ADA) deficiency severe combined immunodeficiency (SCID)

B. Common gamma chain deficiency SCID

C. Recombinase activating gene 1 (RAG1) deficiency SCID

D. CD40 ligand deficiency

E. Wiskott-Aldrich syndrome

You are a doctor in the ED and are clerking a 54 year old male who has presented breathless, with a cough productive of fresh blood. He is a heavy goods vehicle driver who is well aside from a history of hypertension. He is a non-smoker. Clinically there is no sign of DVT. Urinalysis shows ++ for blood. You order an urgent CT pulmonary angiogram (CTPA) which does not show any embolus but the radiologist’s report comments on some haemorrhage bilaterally. What type of hypersensitivity reaction is likely to have caused this clinical picture?

A. Type 1

B. Type 2

C. Type 3

D. Type 4

E. Graft versus host disease

You are the junior doctor on the haematology ward and have been asked to review Josie, a 15 year-old girl who has undergone haematopoeitic stem cell transplantation (HSCT) for treatment of leukaemia. She is currently on day 13 post-transplant and is leukopenic, with a white cell count of 0.4 (normal: 4-11). The nurses on the ward have asked you to review her as her temperature has been high this morning, at 38.5 Celsius. All other observations are within normal limit. As part of your trust’s neutropenic sepsis guidelines, you arrange several investigations including a chest X-ray and commence broad-spectrum IV antibiotics. The chest X-ray report states that Josie has “widespread pulmonary infiltrates across the lung fields with ground-glass consolidation”. By the time the film has been reported, Josie has complained of being short of breath and has had oxygen commenced. Which investigation would confirm the organism suspected of causing these symptoms in Josie?

A. Sputum sample cultured for acid-fast bacilli

B. IgM for cytomegalovirus (CMV)

C. Bronchoalveolar lavage and culture

D. IgM for Epstein-Barr virus (EBV)

E. Blood cultures

You are a GP who is reviewing Ginny, a 9 year-old girl with her mum in clinic. Ginny gives a history of rapid-onset facial swelling and vomiting following eating some birthday cake at a schoolfriend’s party. Since this episode, her mum has restricted her diet. What is the most appropriate investigation to confirm Ginny’s diagnosis?

A. Anti-endomysial antibodies

B. Skin prick testing for a panel of common allergens

C. Exclusion diet and review in 6 weeks

D. RAST for a panel of common allergens

E. Serum C1 esterase inhibitor levels

You are seeing John, who is a 47 year-old man who has undergone renal transplant for polycystic kidney disease. He is currently 4 months post-transplantation and has not been very compliant with his immunosuppressive medication. On routine laboratory investigations you find that his urea and creatinine have been steadily climbing, as has his blood pressure. You suspect chronic organ rejection. Which sign in renal biopsy will confirm the diagnosis of chronic rejection?

A. Infiltrating T-lymphocytes in the renal parenchyma

B. Replacement of glomeruli with fibrous tissue

C. Radiolabelling of immune complexes in the kidney

D. Vascular fibrosis

E. Agglutination of red blood cells

You are the FY1 doctor for paediatrics and are reviewing Maryam, a 4 year-old girl who has presented with a fever and a non-blanching rash. Suspecting sepsis, you take blood for cultures and commence antibiotics as per your Trust’s guidance. Cultures grow n. meningitides. On speaking to the parents, you are intrigued to hear that there is a family history of meningitis and that Maryam’s sister died 4 years ago from overwhelming “septicaemia” before the family moved to the United Kingdom. Maryam also has 2 distant cousins who have died of infection too. Reviewing Maryam’s notes, you notice she has been hospitalised 3 times in the past 2 years for pneumonia, requiring IV antibiotics. Sputum cultures have isolated pneumococcus. Which single investigation is most appropriate to find the underlying of cause of Maryam’s recurrent infections?

A. Immunoassay for HIV antigens

B. Complement assays

C. Serum IgA, IgG and IgM levels

D. Ultrasound scan to identify presence of the spleen

E. T, B, and NK lymphocyte levels

It is the morning ward round on the paediatric ward and you are seeing Kyle, a 15 month-old boy who has come in with widespread petechiae covering his arms, legs and trunk. His parents state that he has always bruised easily but this is the first time it has been so bad; as part of the work-up for suspected non-accidental injury, his platelet count is found to be 13 x10^9/L (normal: 150-400). Blood film examination reveals multiple small platelets. On further history and examination, you find Kyle has long-standing eczema and has received multiple courses of antibiotics for otitis media. On hearing this, your consultant mutters, “Of course! I had almost forgotten about this condition”. Which of the following investigations is most likely to confirm the diagnosis your clever consultant suspects?

A. Direct Coombs’/antiglobulin test

B. Bone marrow aspiration and examination by a haematologist

C. Serum IgG, IgA and IgM

D. Complement function assays

E. Flow cytometry for WASP expression