Mixed Agglutination
Definition
A microscopy-based technique in which indicator cells form rosette aggregates around antigen-bearing stain material via antibody bridges. Positive results are read as characteristic clumping patterns under a low-power objective.
- Technique type
- Microscopy-based ABO typing
- Key observable
- Rosette clumping patterns of indicator cells
- Mechanism
- Antibody bridges connect indicator cells to antigen-bearing stain fibers
- Best for
- Small or limited bloodstain samples
Common questions
How does mixed agglutination work in blood typing?+
Indicator red cells bind to antibodies that are already attached to blood group antigens in a stain sample. Under the microscope, these cells cluster around the stain material, forming rosette patterns. The clumping pattern you see tells you which blood group antigens are present.
When would you use mixed agglutination instead of other typing methods?+
Mixed agglutination is helpful when you have only a small amount of evidence. A few stained fibers are enough to read the result, making it useful for old stains or tiny bloodstain samples where material is scarce.
How do you read the result of a mixed agglutination test?+
The technician uses a low-power microscope objective to observe the stain material. A positive result shows characteristic clumping or rosette formations of the indicator cells. The pattern and extent of clumping indicates which blood group antigens are in the sample.
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...
- Absorption-Elution
- A technique for detecting antigens on dried red cell debris. Specific antiserum is absorbed onto the stain; if the antigen is present,...
- 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...
- 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)...
- 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,...
- Secretor Status
- A genetic trait that determines whether a person expresses their ABO blood group antigens in secreted body fluids such as saliva, semen,...
- Sensitivity Threshold
- The smallest stain on which a technique still gives a reliable read. The key axis for choosing between Lattes, inhibition, elution and...
- Titre
- The concentration of antibody in a solution, expressed as the reciprocal of the highest dilution at which agglutination is still visible. A...
Explained in these topics
- ABO Typing on Stains: Absorption-Elution and InhibitionA microscopy-based technique in which indicator cells form rosette aggregates around antigen-bearing stain material via antibody bridges. Positive results are...
- Techniques for Determining Blood Groups from BloodstainsIndicator red cells coat onto the absorbed antibody bound to the stain fibres themselves; the rosette is read under low-power microscopy. Used when only a few...