Antibody Actions & Classes

What are the five main actions of antibodies?

Neutralizing pathogens, immobilizing pathogens, agglutination and precipitation, cytolysis, and opsonization.

What does neutralization mean?

Antibodies block harmful parts of toxins or viruses to prevent them from causing damage.

What is agglutination and precipitation?

Antibodies clump antigens together (agglutination) or make them settle out of solution (precipitation) for easier removal.

What is cytolysis?

Antibodies trigger the destruction of a pathogen by activating the complement system.

What is opsonization?

Antibodies coat a pathogen to make it easier for phagocytes to recognize and engulf it.

How does complement activation help?

It enhances inflammation, cytolysis, and phagocytosis.

What is IgM?

First antibody made; causes agglutination and activates complement.

What is IgA?

Found in secretions like sweat, tears, saliva, mucus, and breast milk.

What is IgD?

Functions as a receptor on B-cells.

What is IgG?

Most abundant; enhances phagocytosis, neutralizes toxins, activates complement, and crosses the placenta.

What is IgE?

Least abundant; involved in allergic reactions; binds to mast cells and basophils.