Absorption-Elution
Definition
A technique for detecting antigens on dried red cell debris. Specific antiserum is absorbed onto the stain; if the antigen is present, the antibody binds. The stain is then washed and heated to release (elute) the bound antibody, which is detected by agglutinating fresh red cells.
- Heat temperature
- 56 degrees Celsius
- Key advantage
- Most sensitive classical stain grouping method
Common questions
What is the absorption-elution technique used for?+
It is a classical forensic method for determining the ABO blood group of dried bloodstains. The technique identifies blood group antigens in old or dried evidence where direct serological tests may not work.
How does the absorption-elution process work?+
Known antiserum is absorbed onto the dried stain. The excess is washed off, then the bound antibodies are released by heating to 56 degrees Celsius. The eluted antibodies are then tested against indicator cells to determine the blood group.
Why is absorption-elution considered sensitive for bloodstain analysis?+
It is the most sensitive of the classical methods for grouping bloodstains. This makes it particularly useful for degraded or limited evidence where other techniques may fail to produce results.
Related terms
- Antiserum
- Serum collected from an immunised animal containing antibodies directed against a specific antigen or group of antigens. In species identification, antiserum raised...
- Absorption-Inhibition
- A known volume of antiserum is exposed to the stain; the residual unbound antibody is then titrated against indicator cells. A drop...
- Agglutination
- Clumping of red cells that occurs when antibodies in serum bind to incompatible antigens on the cell surface, cross-linking cells into visible...
- Bertillon System
- Alphonse Bertillon's criminal-identification method using eleven standardised body measurements to create a unique record for each arrested person, enabling reliable identification of...
- Blood Group System
- A set of red cell surface antigens encoded by one gene locus or by two tightly linked loci. The International Society of...
- Kriminalistik
- The term coined by Hans Gross for the integrated scientific discipline of crime investigation, encompassing physical examination of evidence, microscopy, chemistry, and...
- Lattes Crust Method
- Classical direct agglutination. A crumb of the dried crust is teased into a drop of known antiserum on a slide. Leone Lattes,...
- Linkage Disequilibrium
- The non-random association of alleles at different loci within a population. Certain HLA allele combinations (e.g., HLA-A1 with HLA-B8 with HLA-DR3) occur...
- 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...
- Phenotype Frequency
- The proportion of a given population that expresses a particular antigen combination. Multiplying phenotype frequencies across independent loci gives the combined frequency...
- Portrait Parle
- Bertillon's standardised verbal description system for recording physical features of a person, including face shape, ear structure, eye colour, and build. It...
- Probability of Exclusion
- The proportion of the population whose blood type differs from that of the stain and who would therefore be excluded as its...
Explained in these topics
- Techniques for Determining Blood Groups from BloodstainsTwo-step technique. Known antiserum is absorbed onto the dried stain, washed off, then heat-eluted at 56 °C and tested against indicator cells. The most sensit...
- Minor Blood Group Systems: MNS, Kell, Duffy, and OthersA technique for detecting antigens on dried red cell debris. Specific antiserum is absorbed onto the stain; if the antigen is present, the antibody binds. The...
- The Pioneers: Locard, Bertillon, Galton, Lattes, GrossLattes's technique for determining the ABO blood group of a dried stain by allowing antibodies to bind to the stain's antigens, then releasing the bound antibo...