Problem Solving Flashcards
Rouleaux
Patient serum that usually has an excess of antibodies that will falsely agglutinate RBCs
What does false agglutination by rouleaux look like?
RBC’s stack up like coins when exposed to patient’s “thick” serum/plasma
Effect of rouleaux on immunohematology procedures
Particularly strong form of agglutination
Most likely to be seen at room temp and at 37 degrees. Usually not seen in AHG phase if washing has occurred
How would you crossmatch a patient with severe rouleaux?
Add 1-3 drops of saline to crossmatch tube
Polyagglutination
Red cells that will agglutinate with any human serum. Usually bacterial induced changes to RBC structure that will match up with a universal antibody that everyone has.
Cause of T polyagglutination
When the T antigen is exposed to bacteria producing neuraminidase. It alters glycophorin B and expose the T antigen. RBCs will agglutinate in almost all normal adult sera and [patient’s generally have negative auto-controls
Cause of Tk polyagglutination
Certain enzymes produced by bacteria that cleave a portion of the paraglaboside structure exposing GluNAc (Tk receptor). RBCs will agglutination in almost all normal adult sera
Cause of acquired B
Enzyme production by some bacteria that will produce a B-like determinant on the surface of RBC’s which may react weakly with antisera B
Tn polyagglutination
Cause by mutation in hematopoietic tissue that is not universally occurring on all cell precursors - leads to the polyagglutination mixed-field looks
Cad polyagglutination
Inherited autosomal dominant condition that produces a Cad antigen on the surface of RBCs. Anti-Sd(a) is naturally occurring autoantibody in most adults & cross reacts with the Cad antigen to cause agglutination
Rare
How can you identify rouleaux vs polyagglutination
Rouleaux can be dispersed with the addition of saline
Define panagglutination
An antibody that causes clumping (agglutination) of red blood cells of all blood groups of a species
When a cold reacting antibody is found in a patient’s serum, is it clinically significant if there is no reaction at the 37 degree phase, just the IS phase?
No
How can you enhance the reactivity of a cold antibody?
Allow to incubate at room temp or at 4 degrees C. Remember than an autocontrol must be added when testing has been reduced to 4 degrees
How can you decrease the activity of a cold anitbody
Continually keep blood at 37 degrees C to decrease the binding of IgM antibodies to RBC surface
How can you absorb the cold agglutinin?
Use REST to attach to IH and H antibodies and remove them from the serum
What is an elution?
Technique to separate an antigen and antibody from each other, destroying the RBC and freeing the bound antibody from the RBC surface so it can be used in testing (like an antibody ID panel)
When is an elution performed?
To remove the antibody on a positive DAT specimen, allowing identification of the antibody
What is a Lui Freeze used for?
Elute an ABO antibody
3 methods of eluting?
- Digitonin - acid elution
- Lui - freeze method
- Heat elution
What is absorption?
Removal of an unwanted antibody from a serum.
Specific attachment of an antibody to it’s antigen on the RBC surface. then centrifuging, and removing the serum with now should be missing the unwanted antibody, leaving all of the other antibodies behind to work with
When is absorption used?
When a cold or warm reactive autoantibody may be masking the presence of an additional alloantibody, making it unrecognizable because of the agglutination caused by the autoantibody
What enzymes are used in blood bank and why might you use them?
Ficin, papain, trypsin, and bromilin
To enhance or diminish reactivity with its antibody which will help in the antibody ID, particularly with multiple or masking antibodies
Enzymes inactivate which antigens
M, N, Duffy, Ss
Disadvantage of both gel and solid phase technology that may be detected in tube testing
Inability to detect complement coated cells
Difficulty determining if an unexpected antibody would be an IgM that has a broad thermal range
Autoantibody
An antibody directed against a self-antigen
How can you find the specificity of the autoantibody?
- Elution then antibody ID, antigen typing
- Demonstration of immune complex formed by certain drugs
- Demonstration of antibodies to penicillin or Cephalothin
What is usually the specificity of warm autoantibodies?
Most frequent is within the Rh system, but may be associated with an antibody
What blood would you use for transfusion in a patient with warm AIHA caused by an autoantibody?
Type specific without the antigen matching the antibody
Describe autoimmune drug-induced hemolytic anemia caused by drug adsorption such as very large doses of penicillins, streptomycins, and cephalosporins
The drug binds to the RBC surface. Antibody attaches to the drug. The DAT may be positive, negative, or mixed field.
Describe the autoimmune drug-induced hemolytic anemia caused by membrane modification from very large doses of cephalosporins.
The drug attaches to the surface of the RBC with corresponding attachment of an antibody or complement.
What could be done to enhance the reaction of an anti-M and why does it work?
Use LISS as the potentiator, lowers pH
Which antibodies can be neutralized using human serum?
Anti-Le(a)
Anti-Le(b)
chido and Rogers
If you had a strongly reacting nonpathogenic anti-I that was reacting in all phases, what could you do to see if there were any hidden IgG’s?
Prewarm to see if you can get the anti-I not to react
Use REST to try and absorb out the anti-I
If a patient has an anti-I, what would be the expected reaction with cord cells?
Negative (ii on cord)
First order or direct exclusion in paternity testing
Child has an antigen that is neither the mother or the alleged father has OR the alleged father has two different antigens in the same system and the child doesn’t have either
Second order or indirect exclusion n paternity testing
Child has an antigen (homozygous) and the alleged father demonstrates a different single (homozygous) marker or antigen
If the alleged father is ss(both little) and the mother is ss (both litter) and the child is Ss, what type of exclusion would this be?
First order or direct exclusion. The child has an antigen that neither the mother nor the alleged father has
If the alleged father is MM, the mother is MM, and the child is MN, what type of exclusion would this be?
First order or direct exclusion
What is Zapp and what is it used for?
- Thiol reagent plus a proteolytic enzyme (Dithiothreital and papain)
- Causes IgG antibodies to fall off the surface of sensitized RBC’s
- Alters the surface antigens of some blood groups
What are DDT and 2-mecraptoethanol? What are they used for?
Sulfhydryl compounds
Break the disulfide bonds on the IgM J chains and leave the IgG intact
Discover mixtures of antibodies, remove or break up masking antibodies
See if there is hidden IgG antibodies underneath cold reacting autoantibodies
When should you use polyethylene glycol?
to enhance agglutination - usually as a potentiator in antibody screen or antibody ID
What is REST and when is it used?
Rabbit erythrocyte stroma technique
Attempts to remove anti-IH, anti-I, and anti-H from reacting to discover any masked reactions such as IgG underneath
What antibodies are absorbed from the serum using REST?
anti-I, anti-H, anti-B, anti-P
What is the purpose of chloroquine?
Break off IgG antibodies so antigen typing can be done on a positive DAT
If you needed to free up antigen on RBCs that are covered with IgG (+DAT), what could you do?
Add chloroquine
