Daily MCQs test - immunoglobulins

MCQ Test on Immunoglobulins

Q1. Immunoglobulins are also known as:

a) Antigens
b) Antibodies
c) Antigens
d) Antiseptics

Q2. Which immunoglobulin is the most abundant in the blood and tissue fluids?

a) IgG
b) IgA
c) IgM
d) IgE

Q3. IgA is primarily found in:

a) Blood
b) Saliva, tears, and breast milk
c) Lungs
d) Connective tissues

Q4. Which immunoglobulin is responsible for allergic reactions?

a) IgG
b) IgA
c) IgM
d) IgE

Q5. Immunoglobulins are produced by:

a) Red blood cells
b) B-lymphocytes (B cells)
c) T-lymphocytes (T cells)
d) Platelets

Q6. IgM is the first immunoglobulin produced during:

a) Primary immune response
b) Secondary immune response
c) Tertiary immune response
d) Allergic reaction

Q7. Which immunoglobulin can cross the placenta and provide passive immunity to the fetus?

a) IgG
b) IgA
c) IgM
d) IgE

Q8. IgE is associated with:

a) Bacterial infections
b) Viral infections
c) Fungal infections
d) Allergic reactions

Q9. IgG is responsible for:

a) Anaphylactic reactions
b) Neutralizing toxins and pathogens
c) Activating complement system
d) Blood clotting

Q10. Which immunoglobulin is found in secretions such as tears, saliva, and colostrum?

a) IgG
b) IgA
c) IgM
d) IgE

Immunoglobulins, also known as antibodies, are proteins produced by B cells of the immune system. They play crucial roles in the body's immune response against foreign substances (antigens), such as bacteria, viruses, parasites, and toxins. Each immunoglobulin class has specific functions, contributing to different aspects of the immune response. Here are the roles of the main immunoglobulin classes:

1. IgG (Immunoglobulin G):

- IgG is the most abundant immunoglobulin in the bloodstream and tissues, making up about 75-80% of all antibodies in the body.

- It provides long-lasting protection and is the major antibody involved in secondary immune responses.

- IgG can cross the placenta, providing passive immunity to a developing fetus during pregnancy.

- It opsonizes pathogens, facilitating their recognition and phagocytosis by immune cells (e.g., macrophages and neutrophils).

- IgG activates the complement system, leading to the destruction of pathogens.

2. IgM (Immunoglobulin M):

- IgM is the first antibody produced in response to an infection or antigen exposure. It is the predominant antibody in the primary immune response.

- It is a pentamer (five units) and is highly effective at agglutination (clumping) of antigens.

- IgM is involved in complement activation, leading to the lysis of cells and destruction of pathogens.

- It plays a critical role in neutralizing viruses and preventing them from entering host cells.

3. IgA (Immunoglobulin A):

- IgA is present in body secretions, such as tears, saliva, breast milk, and mucosal surfaces of the respiratory, gastrointestinal, and genitourinary tracts.

- It provides localized defense at mucosal surfaces, preventing the attachment and invasion of pathogens.

- IgA can neutralize toxins and viruses before they can enter the body.

- In breast milk, IgA provides passive immunity to newborns, protecting them against infections.

4. IgE (Immunoglobulin E):

- IgE is involved in allergic responses and plays a role in defense against parasitic infections.

- It is present in small amounts in the blood but is mainly found bound to receptors on mast cells and basophils.

- When an allergen is encountered, IgE triggers the release of inflammatory mediators, leading to allergy symptoms like itching, hives, and respiratory symptoms.

- In response to parasitic infections, IgE enhances eosinophil-mediated killing of parasites.

5. IgD (Immunoglobulin D):

- IgD is present in very low concentrations in the blood.

- Its precise role in immunity is not fully understood, but it is believed to play a role in B cell activation and regulation.

Overall, immunoglobulins are essential components of the adaptive immune response. They recognize and bind to specific antigens, marking them for destruction by immune cells or neutralizing their harmful effects. The diversity of immunoglobulin classes allows for a coordinated and effective immune response against a wide range of pathogens and foreign substances.