Title: first line of defence
Long Title: IUPAC Gold Book - first line of defence
DOI: 10.1351/goldbook.13151
Status: current

Definition
Surface tissues, notably the skin, respiratory tract, and gastrointestinal tract.

Notes
1) These tissues are rich in immunocompetent cells that form a first line of defense by recognizing pathogens, destroying them with secretory antibodies, or preventing their intrusion into the organism.
2) Internal organs may also have a first line of defense, e.g., the microglia have been considered as a first line of defense against brain infections.

Related Term
- immunocompetent: https://goldbook.iupac.org//terms/view/13277

Source
- PAC, 2012, 84, 1113. 'IUPAC glossary of terms used in immunotoxicology (IUPAC Recommendations 2012)' on page 1166 (https://doi.org/10.1351/PAC-REC-11-06-03)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/13151/html
- json: https://goldbook.iupac.org/terms/view/13151/json
- xml: https://goldbook.iupac.org/terms/view/13151/xml

Citation: Citation: 'first line of defence' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.13151
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Accessed: 2026-05-08T06:51:27+00:00