Titre
Definition
The concentration of antibody in a solution, expressed as the reciprocal of the highest dilution at which agglutination is still visible. A titre of 64 means agglutination was seen at 1:64 dilution. Titre reduction in inhibition tests indicates that antigen was present in the stain extract.
- Field
- Forensic serology, immunology
- Definition
- Reciprocal of highest dilution still showing agglutination
- Example
- Titre of 64 means agglutination visible at 1:64 dilution
- Forensic use
- Titre reduction in inhibition tests indicates antigen present in stain
Common questions
Why does a titre reduction indicate antigen was present in the extract?+
In an inhibition test, antigen from the stain extract binds and neutralises some of the antiserum before it reaches the indicator cells, so less antibody remains active. That leftover antibody agglutinates only at a lower dilution than the untreated control, which is read as titre reduction.
Does a higher titre always mean a stronger or more reliable result?+
A higher titre indicates a more concentrated, potent antiserum, which improves sensitivity for the test, but it does not by itself indicate anything about the strength of the forensic stain being examined. Titre describes the reagent's potency, not the sample's antigen concentration directly.
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...
- Adjuvant
- A substance co-administered with an antigen to amplify the immune response. Freund's Complete Adjuvant (FCA), containing killed mycobacteria in mineral oil, is...
- Antiserum
- Serum collected from an immunised animal containing antibodies directed against a specific antigen or group of antigens. In species identification, antiserum raised...
- Elution
- The release of antibody from antigen, typically by heating to 56-70 degrees Celsius. In the absorption-elution method, this step liberates the antibody...
- Indicator Cells
- Commercially prepared or freshly washed red cells of known ABO group used to detect antibody activity in an eluate or residual antiserum....
- Inhibition Index
- A quantitative measure of PCR inhibitor burden in a DNA extract, derived from the Ct shift of an internal positive control (IPC)...
- Mixed Agglutination
- A microscopy-based technique in which indicator cells form rosette aggregates around antigen-bearing stain material via antibody bridges. Positive results are read as...
- 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...
Explained in these topics
- ABO Typing on Stains: Absorption-Elution and Inhibition
- Antisera Production, Standardisation, and Cross-ReactivityThe highest dilution of an antiserum that still produces a detectable reaction with the target antigen under defined test conditions. Titre is the primary meas...