Cross-reaction

Definition

Cross-reaction occurs when an immune response to one antigen also reacts with a different, structurally similar antigen. This can lead to misdirected immune responses and potential complications in bacterial infections.

5 Must Know Facts For Your Next Test

1. Cross-reactions can lead to autoimmune diseases if the immune system mistakenly attacks host tissues.
2. Molecular mimicry is a common mechanism behind cross-reactions, where bacterial antigens resemble host proteins.
3. Rheumatic fever is an example of a disease caused by cross-reaction following Streptococcus pyogenes infection.
4. Cross-reactivity can complicate vaccine development and efficacy.
5. Diagnostic tests may yield false positives due to cross-reactive antibodies.

Review Questions

• What is molecular mimicry and how does it relate to cross-reaction?
• Give an example of a disease caused by cross-reaction after a bacterial infection.
• How can cross-reactivity affect diagnostic tests?

Related terms

Antigen:

A substance that induces an immune response, often part of pathogens like bacteria or viruses.

Autoimmune Disease: A condition where the immune system mistakenly attacks the body's own cells.

Molecular Mimicry:

A situation where microbial antigens share structural similarity with host proteins, leading to cross-reactive immune responses.