Immunology CH 9: Antibody Functions

What are the 5 antibody classes?

IgM, IgG, IgA, IgE, and IgD

What is the most abundant antibody class in the body?

IgA

What is the most abundant antibody class in the blood serum?

IgG

During fetal development, what antibody class is transferred across the placenta?

IgG

What is the most abundant antibody class in breast milk?

IgA

What is the first antibody class to be secreted during a primary infection?

IgM is the first antibody class

What 2 antibody classes are the most effective at moving out of the blood and into extravasular tissues?

IgG and monomeric IgA

What is the most effective/abundant antibody class that protects mucosal surfaces?

Dimeric IgA

What antibody class binds to Fc receptors on mast cells?

IgE

Why are infants vulnerable to infection during their first year of life?

Infants are building up their antibody levels during their first year of life.

IgM levels in first year of infant life:

Gradually rising, reach high levels after about a year

IgG levels in first year of infant life:

the __ that was being transferred across the placenta declines after birth, but infants start producing their own at 3 months (high levels after about a year and they keep rising till age 5)

IgA levels in first year of infant life:

levels start to rise at 3 months, high levels after about a year.

Infants can get extra through breastmilk

What is neutralization?

When antibodies bind to antigens and prevent them from binding to a host cell receptor

What two antibody classes are the most effective at neutralization?

IgG and IgA

What is the primary neutralizing antibody class at mucosal surfaces?

Dimeric IgA

What is the primary neutralizing antibody class in systemic tissues?

IgG

What two antibody classes are the biggest contributers to activating the complement classical pathway?

IgM and IgG

What is an Fc receptor?

a receptor that binds to the heavy chain constant region of an antibody

What is the heavy chain constant region of an antibody called?

The Fc portion

What antibody class functions in defense against helminth parasites?

IgE

What do IgE antibodies interact with?

mast cells, basophils, and eosinophils

They all have a receptor for IgE

What is antibody dependent mediated cell cytotoxicity? (ADCC)

a process where antibodies bind to a target cell and mark it for destruction by immune cells, primarily natural killer cells

How do infected host cells display pathogens for IgG to bind to in ADCC?

They display them on their surface

How do Natural killer cells bind to IgG?

They bind to IgG using their Fclambda receptor

This allows them to kill the infected cell

What cells does the ADCC complement during the adaptive immune response?

The cytotoxic T cells

What is opsonization?

The process of coating an antigen with a molecule, like an antibody, that facilitates for uptake of the antigen by phagocytes

What is the most important antibody class that functions in opsonization?

IgG

What cells do opsonizing IgG interact with?

Neutrophils and macrophages

What type of infections would a patient with a deficient antibody response be susceptible to?

to extracelluar bacterial infections and some extracellular viral infections

This is because antibodies play a crucial role in neutralizing pathogens, opsonizing bacteria for phagocytosis, and activating the complement system.

What antibody class binds to the surface of mast cells?

IgE

What type of antibody class sensitizes basophils in the upper respiratory tract?

IgD

What antibody class functions with natural killer cells in ADCC?

IgG