Progenitors formed in bone marrow but differentiating elsewhere are
Answer: C
Correct answer: Pre-T cells
All blood cells arise in the bone marrow, but the pre-T cell is the one that leaves before it is finished: it migrates to the thymus, where it rearranges its receptor genes and is selected. Erythroblasts, myeloblasts and NK precursors all complete their development in the marrow.
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A disease due to allergic reaction is
Answer: C
Correct answer: Hay fever
Hay fever (allergic rhinitis) is a type I hypersensitivity to inhaled allergens, usually pollen: IgE on mast cells in the nasal lining is cross-linked, histamine is released, and the result is sneezing, a runny nose and itching eyes. Enteric, yellow and trench fevers are infections - by Salmonella, a virus, and a Bartonella respectively.
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Which of the following white blood cells act as scavengers when they engulf and digest pathogens?
Answer: A
Correct answer: Macrophages
Macrophages are the body’s scavengers: they engulf microbes, dead cells and debris, digest them in lysosomes, and then display fragments of what they have eaten to T cells. B and T cells are lymphocytes and do not phagocytose.
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Rh factor is named after
Answer: A
Correct answer: Monkey
The factor takes its name from the rhesus monkey, in whose red cells Landsteiner and Wiener first raised antibodies to it in 1940, before the corresponding human antigen was recognised.
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Which of the following is correctly matched?
Answer: A
Correct answer: National Institute of Virology – Pune
The National Institute of Virology is at Pune. The others are misplaced: the National Centre for Disease Control (formerly the National Institute of Communicable Diseases) is in Delhi, the Central Drug Research Institute is at Lucknow, and the National Institute of Nutrition is at Hyderabad.
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Which of the following is most likely to produce anaphylaxis in a susceptible individual?
Answer: D
Correct answer: Bee sting
Injected allergen is the danger. Venom entering the bloodstream directly can trigger mast cell degranulation throughout the body within minutes, causing the collapse in blood pressure and the airway swelling of anaphylaxis. Pollen, mould and dust are inhaled, and typically cause a local reaction - rhinitis or asthma - rather than a systemic one.
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Inflammation reaction is brought about by
Answer: B
Correct answer: Mast cells
Mast cells sit in the tissues, especially at surfaces that meet the outside world, packed with granules of histamine and other mediators. When triggered they degranulate, dilating local vessels and making them leaky - the redness, heat and swelling of inflammation. Macrophages contribute cytokines, but the immediate reaction is the mast cell’s.
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Innate immune responses are accompanied by inflammation.
Answer: A
Correct answer: True
Inflammation is the innate response made visible. Damaged tissue and activated macrophages release mediators such as histamine and cytokines, which dilate the local vessels and make them leaky - producing the redness, heat, swelling and pain, and bringing plasma proteins and phagocytes to the site.
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The phagocytes can recognize pathogens by means of _____________________
Answer: C
The pathogens make their initial contact with phagocytic cells (dendrites and macrophages) which possess pattern recognition receptors (PRRs). The PRRs can recognize the highly conserved macromolecules in bacteria and viruses.
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In animals, blood clots serve the function of
Answer: D
Correct answer: repairing damage to the body wall
A clot plugs the breach: it stops the loss of blood and, just as importantly for defence, seals the wound against microbes while the tissue underneath is repaired. It is a physical barrier rather than an immune recognition mechanism - though the mesh of fibrin also traps bacteria within it.
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