Hypersensitivity

In Type I hypersensitivity reactions, the cross-linking of IgE antibodies bound to Fc receptors on mast cells and basophils leads to the release of various mediators. Which of the following is a primary mediator released during this process, and what is its role in the hypersensitivity reaction?

• IL-4; Promotes differentiation of Th1 cells

• Histamine; Increases vascular permeability and smooth muscle contraction

• • TNF-alpha; Induces apoptosis in infected cells

• • IL-10; Suppresses inflammatory responses

Which of the following best describes the primary mechanism of tissue damage in type II hypersensitivity reactions?

• Immune complex deposition

•  Delayed T-cell-mediated response

• Production of granulomas by macrophages

• Direct lysis of cells by NK cells

Steve has been exposed to Strep A bacteria and been diagnosed with acute rheumatic fever. Why is he at risk of heart complications?

• Immune complexes deposit in the heart tissue causing inflammation.

• Antibodies cross-react with heart tissue leading to cell damage.

• Eosinophils directly attack the heart tissue.

• Granulomas form in the heart leading to tissue damage.

Which of the following diseases is associated with Type III hypersensitivity?

• Systemic Lupus Erythematosus (SLE)

• Asthma

• Acute Rheumatic Fever

• Allergic Rhinitis

Which of the following mechanisms is involved in Type III hypersensitivity?

• 1. Direct toxicity by T cells

• Binding of IgM or IgG antibodies to self-antigens on tissues

• Release of histamine by mast cells

• 1. Release of cytokines by immune complexes to activate neutrophils

How long after exposure does a Type IV hypersensitivity reaction typically manifest?

• 1-2 days

• Within minutes

• Within hours

• 3-7 days

Which of the following conditions is an example of a Type IV hypersensitivity reaction?

• Tuberculosis skin test

• Anaphylaxis

• Haemolytic anemia

• Rheumatoid arthritis

The late phase of a Type I hypersensitivity reaction occurs several hours after the initial exposure to the allergen. Which cells cytokines are predominantly involved in this phase?

• • Neutrophils; IL-1 and IL-6

• • Eosinophils; IL-3 and IL-5

• • T cells; IFN-gamma and IL-2

• • B cells; IL-4 and IL-5