Consequences of Antigen–Antibody Binding

What is an antigen–antibody complex?

The structure formed when an antibody binds the antigen it recognizes. 

This complex can trigger various immune responses, such as neutralization, opsonization, or activation of the complement system.

What is affinity?

A measurement of binding strength between antigen and antibody.

What is agglutination?

Antibodies cause microbes to clump.

IgM is more effective than IgG.

Hemagglutination is used for ABO typing and detecting influenza/measles.

What is opsonization?

Antibodies coat microbes, enhancing ingestion & lysis by phagocytes.

What is neutralization?

IgG inactivates viruses by binding their surface; neutralizes toxins by blocking active sites.

What is antibody-dependent cell-mediated cytotoxicity (ADCC)?

Antibodies coat large organisms (e.g., worms); nonspecific immune cells release chemicals to destroy them.

How do IgG and IgM activate complement?

Both trigger complement \rightarrow cell lysis + inflammation.