Adjuvant
Definition
A substance co-administered with an antigen to amplify the immune response. Freund's Complete Adjuvant (FCA), containing killed mycobacteria in mineral oil, is used for primary immunisation; Freund's Incomplete Adjuvant (FIA), without the mycobacteria, is used for booster injections.
- FCA composition
- Killed mycobacteria in mineral oil
- FIA composition
- Mineral oil, no mycobacteria
- FCA use
- Primary immunisation only
- FIA use
- Booster injections
Common questions
Why is FCA restricted to the first injection only?+
Its strong inflammatory reaction, driven by the mycobacterial component, can cause tissue damage and granuloma formation if repeated, so protocols switch to the milder FIA for later boosts.
What does the adjuvant actually add to the immune response?+
It creates a local depot effect and recruits immune cells to the injection site, producing a stronger and longer-lasting antibody titre than the antigen would elicit alone.
Related terms
- Absorption
- The purification technique in which a crude antiserum is mixed with antigen preparations from cross-reacting species. Cross-reactive antibodies bind those antigens and...
- Antiserum
- Serum collected from an immunised animal containing antibodies directed against a specific antigen or group of antigens. In species identification, antiserum raised...
- Monospecific Antiserum
- An antiserum that reacts exclusively with proteins from the target species after absorption against all cross-reacting species has been performed and verified....
- Phylogenetic Cross-Reactivity
- The reaction of an antiserum with proteins from non-target species whose proteins are structurally similar due to shared evolutionary ancestry. Cross-reactivity intensity...
- Titre
- The concentration of antibody in a solution, expressed as the reciprocal of the highest dilution at which agglutination is still visible. A...