OIA1010 IMMUNOGLOBULIN & ANTIBODIES

What are immunoglobulins (Igs)?

Glycoproteins produced by plasma cells that recognize and neutralize foreign objects like bacteria and viruses​.

How are antibodies and immunoglobulins related?

They are often used interchangeably, but immunoglobulins are the structural class of antibodies​.

What activates B cells to produce antibodies?

Binding to specific antigens, sometimes with T helper cell interaction​.

What is the primary function of antibodies?

To bind antigens and eliminate them by neutralization, opsonization, or complement activation​.

What are the components of an antibody?

Two identical heavy (H) chains and two identical light (L) chains held by disulfide bonds​.

What is the Fc region of an antibody?

The stem of the "Y" that binds to cell receptors and complement proteins, mediating immune responses​.

Define the variable (V) and constant (C) regions in antibodies.

The V region binds antigens; the C region defines the immunoglobulin class and mediates effector functions​.

What types of light chains exist in antibodies?

Kappa (κ) and Lambda (λ), but only one type is present in each antibody​.

What is the hinge region in antibodies?

A flexible region where the antibody arms form a Y shape, allowing movement​.

Differentiate between affinity and avidity.

Affinity is the strength of binding between an antibody and antigen; avidity is the total strength of multiple bindings​.

What are epitopes?

Specific parts of antigens that antibodies bind to​.

What bonds stabilize antibody structure?

Inter-chain and intra-chain disulfide bonds​.

What are the five immunoglobulin classes?

IgA, IgD, IgE, IgG, and IgM​.

Which antibody is most abundant in blood?

IgG​.

Which antibody is the first produced in an immune response?

IgM​.

Which antibody is found in secretions like saliva and tears?

IgA​.

Which antibody mediates allergic reactions?

IgE​.

What is the function of IgD?

It serves as a receptor on immature B cells​.

How does IgG protect newborns?

It crosses the placenta to provide passive immunity to the fetus​.

What is the structure of IgA in secretions?

A dimer with a J chain and a secretory component​.

How does IgM function in the immune response?

As a pentamer, it has high avidity and is highly effective in complement activation​.

What role does IgE play in hypersensitivity reactions?

It binds to mast cells and basophils, triggering histamine release in allergic responses​.

Which IgG subclass is the most effective at complement activation?

IgG3, followed by IgG1 and IgG2​.

Which immunoglobulin is mainly involved in mucosal immunity?

IgA​.

What is selective IgA deficiency?

A condition where IgA is absent or decreased, leading to increased susceptibility to infections​.

Why is IgM called a "natural antibody"?

It arises early in life and reacts to naturally occurring antigens​.

Which antibodies are involved in blood transfusion reactions?

IgM, due to its role in agglutination of red blood cells​.

How do antibodies facilitate opsonization?

By coating pathogens to enhance phagocytosis​.

Which antibody cannot activate the complement system?

IgG4​.

What is the J chain in antibodies?

A polypeptide that joins monomers in IgA and IgM to form dimers or pentamers​.