Immunologic and Genetic Principles Flashcards
(21 cards)
Protein analysis provides information that may not be obtainable by _________ _________ testing.
Nucleic acid
True or false: it is not possible to detect antibodies by nucleic acid testing.
True
The presence of _______ does not always correlate with the presence of encoded protein.
mRNA
Several different ______ __________ may be required for the expression of some blood group antigens.
Gene products
State three applications of agglutination methods.
Serologic crossmatching
Screening plasma for unexpected antibodies
Blood group antigen phenotyping
Name three methods of demonstrating agglutination.
Tube testing (centrifugation)
Passive agglutination in microtitre plates
Gel testing
What is the zone of equivalence?
A ratio of antigen to antibody that is in a range such that agglutination occurs easily
Antibody excess causes a __________ effect.
Prozone
__________ excess causes a post-zone effect.
Antigen
List two causes of a prozone effect.
Very high titre antibody
Discrepant ABO results
A large excess of red cells can cause a __________ effect.
Post-zone
What events occur in solid-phase testing.
The antigen or antibody is immobilised on a solid matrix
Analyte is then incubated with the coated solid phase and adherence of the analyte is measured
List three ways in which solid-phase red cell adherence can be used.
Phenotyping red cells
Detecting antibodies to red cell antigens
Phenotyping cells other than red cells
What role does ELISA play in the transfusion laboratory?
Can detect either antibodies or antigens
Signal generated by an enzyme linked to either a secondary antibody or antigen
Signal amplification aids sensitivity
Describe three features of protein microarrays.
Increased number of substrates can be simultaneously assayed
Numerous different protein substances can be ‘spotted’ on a small chip in an ‘array’
A single specimen can be assayed for binding activity to multiple (thousands) substances simultaneously
What role does Western blotting play in immunohaematology?
Often used as confirmatory test for screening serological tests for infectious agents, such as HIV
List five applications of flow cytometry in transfusion science.
Red cell phenotyping, (useful for transplanted or heavily transfused patients)
Detection of platelet antibodies
Detection of RhD-positive foetal cells (more accurate than Kleihauer-Betke stain)
Identification of transfused donor red cells
Assessing the quality of leucodepletion
Describe two limitations of serological analysis.
In HDFN, monitoring antibody levels in maternal serum an indirect method for indicating risk to newborn
Phenotyping multi-transfused patients can be difficult, as can phenotyping cells that are coated with IgG
Describe the use of PCR technology in transfusion science.
Allele-specific probes (specific genes are amplified by PCR)
RFLP analysis and Southern blotting (fragments of DNA separated by electrophoresis, transferred to special membrane, and incubated with DNA probes)
Commercially available genotyping systems are available, such as PCR-SSP with gel electrophoresis
State five applications of PCR-assisted transfusion tests.
Phenotyping transfused patients
Phenotyping red cells that have been coated with IgG antibody
Establishing blood group gene zygosity
Detecting weakly expressed antigens on red blood cells (e.g., Fyx)
Detecting antigens for which it is difficult to find antibodies of sufficient potency (e.g., Dombrock, Colton, Vel, etc.)
Describe the function and process of the microarray method.
Detect multiple parameters simultaneously
Nucleotide sequences (probes) are spotted onto a small chip
Addition of PCR-prepared material from donor/patient occurs
cDNA is then added
Fluorescence pattern can be analysed by software, such as BLOODchip ID- Luminex/Grifols
