Transfusion Medicine Lab Questions

Bill Bailey misread procedure directions and forgot to centrifuge his agglutination reactions.

What effect would this have on the correctness of Bill's interpretation of the agglutination results?

Could give a weaker reaction or false negative – cells would not be brought together to allow proper agglutination (stage II – lattice formation)

This exercise demonstrates the appearance of hemolysis in an agglutination test using water.

What is the significance of hemolysis when it appears in routine test tube agglutination?

Hemolysis can be an indication of an antigen/antibody reaction, and rarely there is no agglutination seen so it’s critical to observe and record any hemolysis. While the reason for hemolysis in this exercise was the hypotonic state caused by water, it was intended to alert you to always observing for hemolysis before tipping the tubes.

Under what conditions must Serofuge QC such as timer and RPM checks be done?

Upon receipt (before putting into service), after any maintenance or repair, and periodically according to manufacturer’s recommendations and facility policy.

In this exercise you will perform both slide typing and tube typing on patient unknowns. What does the slide typing test?

Antigens on the red blood cells. Slide typing is not routinely done. You will not do it again in this course. It is far less sensitive than tube testing or other methods

What does the tube typing test?

Antigens on the red cells and antibodies in the plasma. Tube testing is more sensitive, allowing the detection of subgroups. It also allows the confirmatory aspect of the reverse typing.

Several factors can influence ___ reactions, including temperature, suspending medium, centrifugation, and ratio of ___ to ___

agglutination; antigen; antibody

List one advantage of each method of ABO grouping (tube and slide)

Slide - quick and less equipment needed
Tube - more sensitive, can do confirmatory backtype

How are reagent A1 and B cells made?

Human donors are used, and cells from many donors are pooled together, washed, and resuspended in diluent containing preservatives to the proper strength

List the ABO blood types in their order of frequency in the general U.S. population, from highest to lowest. Include the A2 and A2B subtypes.

O>A1>B>A2>A1B>A2B Note: for subgroups you would multiply the subgroup frequency times the blood group frequency i.e. A2 is 20% x 40% in Caucasians = 8%, so it is less common than B

What could happen if you added reagent cells to your tubes before adding serum when performing a blood typing procedure?

You wouldn’t know if you forgot serum, i.e. false negative might occur. You can’t visualize the serum when red cells are present.

What federal agency sets regulations for the quality of commercial antisera?

The Center for Biologics Evaluation and Research branch of the FDA

What are lectins?

Saline extracts of plants that have specificity for certain blood groups.

Which lectin reacts with A1 antigens?

Dolichos biflorus

Which lectin reacts with H antigens?

Ulex europaeus

Which lectin reacts with B antigens?

Bandeiraea simplicifolia

What are two reasons to use anti-A,B (Group O serum) when typing red cells?

-To resolve typing discrepancies i.e. Ax subgroup reacts with anti-A,B but not with anti-A

-To confirm the anti-A and anti-B results (not commonly done)

What conditions could cause weak or missing ABO antibodies (i.e. do not meet Landsteiner’s Law)?

Newborns, elderly, immunosuppressed, chemotherapy, technical errors.

Why is the agglutination with the commercial ABO antisera in the forward type usually stronger than that seen in the reverse typing?

Commercial antisera are produced by monoclonal technology to have high titers, whereas a random person will have an unknown titer depending upon their age and diagnosis and individual immune system.

Why is it important that a technologist recognize a mixed field reaction?

So that the correct type of blood is transfused and the correct type is put into the historical record

Briefly explain how the secretor test works for detection of A, B, and H substances.

Saliva (secretion) is incubated with known antisera (A, B and H). If A, B or H substances are present, they will be neutralized by the antisera. Corresponding test cells are then added. A positive (agglutinated) result = non-secretor. A negative (not agglutinated) result = secretor.

Give the Wiener designation for the following Fisher-Race notations.

D; c; E; cDe; cDE; cde; CDE

Rho; hr’; rh”; Ro; R2; r; Rz

Give the Fisher-Race genotype for the following Weiner genotypes. r”r’; R1ry; R1R2

cdE/Cde; CDe/CdE; CDe/cDE

Of the three genotypes: cdE/Cde, CDe/CdE, CDe, cDE, which one is most commonly found in the general population?

CDe/cDE = R1R2