This set of Immunology Multiple Choice Questions & Answers (MCQs) focuses on “Antibody-Mediated (Type II) Hypersensitivity Reactions”.
1. Which of the following is referred to as Type II Hypersensitivity reaction?
a) Immediate hypersensitivity
b) Cytotoxic reaction
c) Immune complex reaction
d) Cell mediated hypersensitivity
View Answer
Explanation: Type II hypersensitivity is also referred to as Cytotoxic reaction. Cytotoxicity is defined as a state of being toxic to the cells. This means that type II hypersensitivity has a role in controlling the toxic actions of the cells. It is also involved in controlling several autoimmune diseases. Type II hypersensitivity reaction occurs when the host tissue is damaged by cellular lysis when there is direct binding of antibody to cell surface antigens.
2. Which two important antibody isotypes are involved in type II hypersensitivity action?
a) IgM & IgE
b) IgG & IgA
c) IgM & IgG
d) IgD & IgA
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Explanation: IgG and IgM are the two major antibody isotypes that are directed against cellular antigens which are also termed as the foreign antigens that affect the functioning of the cells. These two types are involved for their actions to be played while type II hypersensitivity reactions. They help in enhancement of immune activation and also induce phagocytosis wherever and whenever necessary.
3. Which phases are involved in mechanism of Type II hypersensitivity?
a) Sensitization and Reactor Phase
b) Sensitization and Effector Phase
c) Reactor and Effector Phase
d) Effector and Cytotoxic Phase
View Answer
Explanation: Type II hypersensitivity reactions occur by following a certain flow of mechanisms. It basically occurs in two phases that are sensitization and effector phase. Production of antibodies leading to recognition of metabolites which help in building up and enlargement of membranous structures of cells takes place in the first phase i.e., sensitization phase. On the other side of this mechanism, we have the effector phase, which helps in targeting the cells and force them to get associated by antibodies in order to avoid destruction or its damage once these cells come in contact with the foreign particles or allergens.
4. Type II hypersensitivity does not occur in which of the following human organs?
a) Lungs
b) Skin
c) Uterus
d) Thyroid
View Answer
Explanation: Type II hypersensitivity does not occur in Uterus. Type II hypersensitivity reaction is also called antibody mediated hypersensitivity reaction because this is the differentiating feature from other types of hypersensitivity. It occurs in various parts of the human body such as lungs, skin, nerves, blood system as well as thyroid.
5. Type II hypersensitivity can be treated by steroids.
a) True
b) False
View Answer
Explanation: Depending on the causes of type II hypersensitivity reactions, different methods are used for treatment. They include use of steroids as well as techniques like Intagram infusion and plasmaphoresis. Steroids like prednisolone and dexamethasone in high dosage can treat hypersensitivity type II. Depending on the seriousness of the hypersensitivity, steroid use can be either long term or short term.
6. Which disease is caused when a human’s immune system accidently attacks thyroid?
a) Lupus
b) Rheumatoid arthritis
c) Grave’s disease
d) Diabetes
View Answer
Explanation: Grave’s disease is caused when immune system accidently attacks the thyroid hence it is also called as one of the most common autoimmune disease. It is an involuntary action of immune system which can be misled to attack the thyroid. This attack leads to production of excess of thyroid hormones in the body. This condition is also known as hyperthyroidism.
7. Type II hypersensitivity reaction occurs when IgG bind to which receptor on cell surface?
a) Fc receptor
b) B cell receptor
c) T cell receptor
d) Complement receptor
View Answer
Explanation: Antibodies like IgG mediate the response of type II hypersensitivity by binding to the surface of the target cell. They bind specifically to the Fc receptor in order to get in contact with target cell and act as opsonin. Opsonin is a molecule which enhances phagocytosis. As and when IgG binds to the target cell surface through Fc receptor, it activates the process of phagocytosis which affects the target cells.
8. Which of the following disease is not caused by Type II hypersensitivity reaction?
a) Mysanthia gravis
b) Grave’s disease
c) Pernicious anemia
d) Atopic dermatitis
View Answer
Explanation: Atopic dermatitis is caused by Type IV hypersensitivity reaction. Type IV hypersensitivity affects various parts of body like skin and lungs. Atopic dermatitis is caused by inflammation of skin which results in redness of skin and can also cause swelling. On the other hand, Mysanthia gravis, Grave’s disease and Pernicious anemia are some of the diseases that are caused by type II hypersensitivity reaction.
9. In the complement pathway of type II hypersensitivity, antibodies binding to the surface of target cell results in the formation of which complement component?
a) C3a
b) C3b
c) C3d
d) C3c
View Answer
Explanation: Complement pathway of type II hypersensitivity results in the formation of C3b complement component when antibodies bind directly to the surface of target cells. C3b acts as an opsonin which enhances phagocytosis and promotes binding to the receptor on surface of macrophages. This binding results in activation of macrophages which causes engulfment of cell resulting in destruction and depletion of cell.
10. Which hemolytic disease is caused in new-borns due to the reaction of type II hypersensitivity?
a) Erythroblastosis fetalis
b) Haemorrhagic disease
c) Newborn jaundice
d) Neonatal infection
View Answer
Explanation: Hemolytic disease in new-born babies occurs due to type II hypersensitivity reaction. It takes place via maternal antibody isotype IgG which overlaps the placenta. This results in erythroblastosis fetalis. This case is very rare as it develops if an Rh- mother gives birth to Rh+ foetus. In such a condition, the maternal antibodies transmit to form fetal red blood cells and this results in incompatibility between maternal and fetal blood groups.
Sanfoundry Global Education & Learning Series – Immunology.
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