Q: Which equation correctly represents the time frame for clinical symptoms in Type III (immune complex) hypersensitivity reactions?

$$3 \u003c t \u003c 8 \text{ hours}$$

Question 1

Which of the following best describes a Type I (anaphylactic) hypersensitivity reaction?

Accepted Answer

It is an immediate reaction caused by IgE binding to mast cells and basophils, resulting in degranulation and release of mediators.

Question 2

A patient develops hives and difficulty breathing within minutes of eating peanuts. Which mediators are most likely responsible for these symptoms?

Accepted Answer

Histamine, prostaglandins, and leukotrienes released from mast cells

Question 3

Which equation correctly represents the time frame for clinical symptoms in Type III (immune complex) hypersensitivity reactions?

Accepted Answer

$$3 \u003c t \u003c 8 	ext{ hours}$$

Question 4

Which of the following is a clinical sign of systemic allergic reactions?

Accepted Answer

Degeneration of mast cells causes the release of large amounts of histamine and inflammatory mediators.

Question 5

Which of the following best explains the mechanism of Type II hypersensitivity reactions?

Accepted Answer

Antibodies (IgG or IgM) directed against cell surface antigens activate complement, leading to cell lysis.

Question 6

A patient receives a mismatched blood transfusion and develops hemolysis. Which type of hypersensitivity reaction is this?

Accepted Answer

Type II (cytotoxic)

Question 7

Which of the following is a characteristic sign of localized Type I hypersensitivity reactions?

Accepted Answer

Marked by watery nasal discharge, sneezing, itchy throat and eyes, and excessive tear production.

Question 8

Which of the following is true regarding allergy 'vaccines'?

Accepted Answer

They induce tolerance by promoting the formation of blocking IgG antibodies.

Question 9

Which of the following is an example of an autoimmune disease characterized by autoantibodies against nuclear materials?

Accepted Answer

Systemic lupus erythematosus (SLE)

Question 10

A patient develops a butterfly-shaped rash across the nose and cheeks and tests positive for autoantibodies against nuclear materials. Which process is most likely occurring?

Accepted Answer

Autoimmune destruction of self tissues

Question 11

Which of the following best describes an allograft?

Accepted Answer

A graft from a genetically different individual of the same species

Question 12

Which immune cells are primarily responsible for delayed (Type IV) hypersensitivity reactions?

Accepted Answer

Cytotoxic T cells and helper T cells

Question 13

Which of the following is a privileged site where grafts are less likely to be rejected?

Accepted Answer

Cornea

Question 14

Which equation best represents the time after exposure for clinical symptoms in Type IV (delayed cell-mediated) hypersensitivity?

Accepted Answer

$$t \u003e 1 	ext{ day}$$

Question 15

Which of the following is a mechanism by which privileged sites prevent immune rejection?

Accepted Answer

They lack lymphatic drainage and have blood vessels impermeable to lymphocytes.

Question 16

A patient receives a kidney transplant and develops rejection within days. Which type of graft rejection is most likely?

Accepted Answer

Hyperacute rejection due to preformed antibodies

Question 17

Which of the following immunosuppressive molecules inhibits T cell and B cell reproduction?

Accepted Answer

Cyclosporin

Question 18

Which of the following is a clinical sign of anaphylactic shock?

Accepted Answer

Constriction of smooth muscle of the bronchi

Question 19

Which of the following best describes the role of blocking antibodies in allergy immunotherapy?

Accepted Answer

They bind to allergens and prevent IgE from interacting with mast cells.

Question 20

Which of the following is a common feature of autoimmune diseases?

Accepted Answer

They often involve the production of autoantibodies and cytotoxic T cells against self tissues.

Hypersensitivity Reactions, Allergy, and Autoimmune Diseases in Microbiology 19

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