Blood Bank Clinical Study Questions Flashcards
What immunoglobulin class is primarily associated with the antibodies of the ABO system?
IgM
What is weak-D (Du)?
Occasionally, an individual will have significantly decreased amounts of the D antigen, and therefore will not test positive at immediate spin but will show positive on an IAT.
Why are controls used in weak-D testing, and what is done if the control is positive?
Controls are used to confirm that all reagents are working properly, since weak-D will not show up on immediate spin like full expression of D will. If the control is positive, the test is invalidated and must be repeated.
What Rh type blood products would be given to a person who was weak-D positive?
Rh=. **Blood from a weak-D positive donor is always considered Rh+. However, some weak-D positive patients can actually have a partial or mosaic form of D, and receiving Rh+ blood could still cause them to produce anti-D.
From what plant does the anti-H lectin come from?
Ulex europaeus
What effect does time have on agglutination reactions?
antibodies and antigens must be given an appropriate amount of time to react with one another; too little time can lead to a false =, while too much time can lead to a false +
What effect does temperature have on agglutination reactions?
depending on the type of antibody (ex. cold or warm auto), temperature can affect whether or not the anitbody reacts
What effect does centrifugation have on agglutination reactions?
enhances the reactivity by forcing the antigens and antibodies closer to one another
Which blood group system is the only system in which the antibodies are consistently and predictably present in the serum of normal individuals whose red blood cells lack the antigen?
ABO
What are the eight important subgroups of A?
A1, Aint, A2, A3, Am, Ax, Ael, Ay
What type of problems can subgroups of A cause in the laboratory?
they can cause discrepancies in the ABO typing process
What antibody is commonly found in some subgroups of A that can cause ABO discrepancies?
anti-A1
Mixed-field agglutination in ABO grouping would most likely be caused by what group?
A3
What is the H substance?
the precursor of the A and B antigen, formed by the addition of fucose to the terminal galactose on either Type I or II chains.
What is the minimal acceptable weight for donating blood?
> /= 110lbs (50kg)
What is the acceptable temperature for donating blood?
= 37.5C (99.5F)
What is the acceptable range for pulse when donating blood?
50-100 bpm
What is the acceptable blood pressure for donating blood?
systolic:
What is the acceptable hemoglobin level for donating blood?
> /= 12.5 g/dL
What is the acceptable hematocrit level for donating blood?
> /= 38%
What is Landsteiner’s Rule?
antibodies are present in plasma only when the corresponding antigen is not present on the red blood cells
What is the principle of the copper sulfate method for determining hemoglobin based on?
Copper sulfate has the same specific gravity of blood with a hemoglobin measurement of 12.5 g/dL, the minimum for blood donation. If a drop of blood placed into a copper sulfate solution is maintained within 12 seconds, hemoglobin is adequate. If the drop sinks, the hemoglobin is higher than 12.5; if it floats, the hemoglobin is lower than 12.5.
What is the specific gravity of copper sulfate?
1.053
What is an autologous transfusion?
any transfusion of blood or blood components that have originated with the recipient
What is therapeutic phlebotomy?
the removal of blood for medical reasons
What is plasmapheresis?
the withdrawal of blood from a donor and subsequent return of red blood cells
What are packed red cells?
blood from which plasma has been removed
What does leukoreduced mean?
at least 70% of the original white blood cells have been removed but at least 70% of the original red blood cells have been retained
What is cryoprecipitate?
the cold insoluble portion of plasma remaining after FFP has been thawed
What are frozen-stored red blood cells?
prepared by freezing red blood cells using glycerol as the cryoprotective agent
What is the criteria for the age of compatibility testing specimens?
For patients who have, in the last three months, been pregnant or have received a transfusion (or if the history is uncertain or unavailable), the sample used for compatibility testing must be obtained from the patient within three days of the scheduled transfusion; this represents the patient’s current immunological status, and complement is present in fresh plasma only. **There’s not set time limit on crossmatch specimens for patients who do not meet this criteria, though some hospitals set the three-day limit for all specimens to avoid problems.
What is the most current preservative used for blood storage?
CPDA (citrate-phosphate-dextrose-adenine)
What is the shelf life of CPDA-stored blood?
35 days @ 1-6*C
Define allele.
one of two or more different genes that may occupy a specific locus on a chromosome
Define phenotype.
the outward expression of genes; on blood cells, the serologically demonstrable antigens constitute the phenotype, except those sugar sites that are determined by transferases
Define locus.
the site of a gene on a chromosome
Define silent allele.
a gene that does not appear to produce a detectable antigen
Define heterozygous.
possessing two different alleles at a given gene locus
Define Rouleaux, including causes.
“stacked coin” appearance of RBCs; may be artifactual (as on thick blood smears) or caused by abnormal proteins, increased fibrinogen, and increased globulins, such as in infection and inflammation, and disease states (multiple myeloma, Waldenstrom’s, cirrhosis, etc.)
Define amorph.
another name for “silent allele”
Define alloimmunization/isoimmunization.
development of antibodies in response to alloantigens (derived from a genetically dissimilar animal of the same species) such as following a transfusion
Define LISS.
Low Ionic Strength Solution; enhances agglutination reactions by reducing the zeta potential and increasing the amount of antibody taken up by the RBCs
Define Bombay phenotype, including all antibodies present in the serum.
hh, Oh; RBCs do not express the H antigen, and therefore cannot express the A or B antigens, no matter what their genotype. Serum contains anti-A, anti-B, and anti-H, so Bombay individuals can only receive blood products from other Bombay individuals.
Define compatible.
donor red cells that do not contain the antigens that correspond to antibodies present in the recipient serum
Define homozygous.
possessing a pair of identical alleles at a given gene locus
Define kernicterus.
also known as bilirubin encephalopathy; a disorder causing severe jaundice in newborns, wherein bilirubin is deposited in the brain, potentially leading to athetoid cerebral palsy, hearing/vision problems, or mental retardation
Define incomplete/blocking antibody, including antibody class.
IgG class; antibodies that do not cause agglutination when suspended in saline, however they do block the antigenic sites on RBCs so that subsequent addition of complete antibody of the same antigenic specificity does not cause agglutination.
Define Wharton’s jelly.
Gelatinous substance within the umbilical cord, largely made up of mucopolysaccharides, derived from extra-embryonic mesoderm. To remove it, RBCs must go through several wash cycles with isotonic saline.
Define genotype.
an individual’s actual genetic makeup
Define homologous antigen and antibody.
the specific antigen that generates the formation of an antibody that in turn can react with that antigen