Immunology - Immunoglobulins

Flashcards covering key concepts about immunoglobulins, their structure, classes, functions, and distribution based on lecture notes.

Which part of the heavy chain variable region contributes to antigen binding?

Fd region

What part of an antibody determines its class and function?

Constant region

Which region of an antibody binds antigen and is unique to each antibody?

Variable region

What is the large polypeptide chain of an antibody that defines its immunoglobulin class?

Heavy chain

What is the smaller polypeptide chain paired with the heavy chain that contributes to antigen binding?

Light chain

What is the antigen-binding fragment of an antibody?

Fab region

Which constant portion of an antibody binds immune cells and complement?

Fc region

What is dimeric IgA found in mucosal secretions called?

Secretory IgA

What is the structural form of IgM?

Pentamer

What is the secretory structural form of IgA?

Dimer

List the five classes of immunoglobulins.

IgG, IgA, IgM, IgE, IgD

Which immunoglobulin is a monomer, most abundant (70-75%), crosses the placenta, and is involved in the secondary immune response, found in blood/tissues?

IgG

Which immunoglobulin is a monomer in serum but a dimer in secretions (like tears, saliva, breast milk) and provides mucosal immunity?

IgA

Which immunoglobulin is a pentamer, the first antibody made in a primary response, and is known for strong agglutination and complement activation?

IgM

Which immunoglobulin is a monomer, involved in allergy and parasitic infections, and binds to mast cells and basophils?

IgE

Which immunoglobulin is a monomer, found in low amounts in serum, and is important as a B-cell receptor?

IgD

What are the main structural components of an immunoglobulin?

2 Heavy chains (class-specific), 2 Light chains (κ or λ), Variable region (antigen binding), Constant region (class/function), Fab region (binds antigen), Fc region (binds immune cells/complement)

Where is IgG primarily found in the body?

Serum, tissues, and crosses the placenta

Where is IgA primarily found?

Mucosal secretions (tears, saliva, breast milk, gut), and some in serum

Where is IgM primarily located?

Blood and lymph, and on the surface of immature B cells

Where is IgE primarily found in the body?

Bound to mast cells and basophils in tissues

Where is IgD primarily found?

On the surface of B cells, and in small amounts in serum

What percentage of total immunoglobulins does IgG represent?

~70–75%

What percentage of total immunoglobulins does IgA represent?

~10–15%

What percentage of total immunoglobulins does IgM represent?

~10%

What percentage of total immunoglobulins does IgD represent?

What percentage of total immunoglobulins does IgE represent?