Immune System Questions and Answers

Answer: C

Correct answer: Aldara

Aldara is imiquimod, which stimulates TLR7 and so provokes a local release of interferon and other cytokines. It is applied to the skin for genital warts, actinic keratoses and superficial basal cell carcinoma. Doxorubicin is a cytotoxic drug, neosporin an antibiotic ointment, and vimentin a structural protein.

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.

Answer: C

Defensins are antimicrobial peptides synthesized by the lymphocytes and epithelial cells. The defensins can bind to various pathogenic bacteria and bring about their demise. Similarly, blood also contains complement - a group of soluble proteins that carry out the destruction of pathogens.

Answer: A

Correct answer: natural killer cells

Natural killer cells deal with pathogens hiding inside cells. They do not recognise the pathogen itself; they check whether a cell is displaying its normal MHC class I molecules, and kill it if it is not - which is exactly the state a virus-infected or tumour cell tends to be in. Being part of innate immunity, they act without any prior exposure.

Answer: A

In a type of antiviral response initiated within the cell, type I interferons (IFN-alpha and IFN-beta) are produced and secreted into the extracellular space where they bind to noninfected cells and render them resistant to subsequent viral infections.

Answer: A

Acquired (or adaptive) immune systems are more specific than the innate immune responses and can distinguish between two very similar molecules. The adaptive immune responses possess a memory i.e. an individual cannot develop the same disease twice.

Answer: C

Correct answer: lymphocytes

Humoral immunity depends on antibodies, and antibodies are made by B lymphocytes after they mature into plasma cells - with helper T lymphocytes, also lymphocytes, providing the signals that permit it. Mast cells and neutrophils belong to inflammation and phagocytosis; leucocyte is the general word for a white cell, of which lymphocytes are one kind.

Answer: A

Correct answer: hematopoietic stem cells

Both arise from the haematopoietic stem cells of the bone marrow. B cells complete their maturation there; T cells migrate to the thymus to mature, which is what the T stands for. Germ cells give rise to gametes, and have nothing to do with it.

Answer: A

Correct answer: humoral antibody

Congenital agammaglobulinaemia - Bruton’s disease - is a failure of B cells to mature, so almost no immunoglobulin is made. The defect is therefore in the humoral (antibody) arm. Cell-mediated immunity is intact, which is why such patients handle viruses reasonably well but suffer repeated bacterial infections, the very ones antibody normally controls.

Answer: D

Correct answer: antibody

An antibody (immunoglobulin) is the Y-shaped protein secreted by plasma cells, with two binding sites shaped to fit one particular antigen. Binding neutralises the antigen, marks it for phagocytosis, or triggers complement. A phagocyte and a leucocyte are cells; a vaccine is a preparation that provokes antibody rather than being one.