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Question	Answer
Define clinically significant antibody in your own words. What outcomes are we worried about? An antibody that can cause real harm in a patient—especially hemolytic transfusion reactions (HTR) and hemolytic disease of the fetus/newborn (HDFN).
What three features usually predict significance? IgG class, reacts at 37°C/AHG, and associated with in vivo hemolysis (HTR or HDFN).
Why do many cold-reactive antibodies tend to be “nuisance” antibodies in transfusion workups? They react at room temp or colder, show up in testing, but usually don’t cause clinical harm—just interfere with interpretation.
Give one example of an antibody that is usually significant and one that is usually insignificant. For each, explain why. Significant: Anti-K (IgG, warm, causes HTR/HDFN). Insignificant: Anti-Lea (IgM, cold, doesn’t cross placenta, no HDFN).
What does it mean to be “Rh positive” and which antigen specifically determines that label? It means the person has the D antigen on their red blood cells; D determines Rh positive.
Explain the difference between Fisher-Race and Wiener naming. What is each system trying to describe? Fisher-Race lists three separate genes (C/c, D/d, E/e); Wiener uses a single code (R1, R2, etc.) to represent the whole Rh haplotype. Both describe the
Why is there no true “d antigen”? What does “d” actually mean? “d” is just the absence of D; there is no physical d antigen.
In one sentence: why is anti-D such a big deal in blood bank? Because it is IgG, crosses the placenta, and can cause severe HDFN and significant transfusion reactions.
What is a haplotype in the Rh system? Why do we talk about haplotypes instead of single antigens? A haplotype is the set of Rh genes (C/c, D/d, E/e) on one chromosome; we use haplotypes because these genes are inherited together as a unit.
Write out the Fisher-Race equivalents for these Wiener terms (from memory or your chart): R1, R2, R0, r, r’, r’’. R1 = CDe; R2 = cDE; R0 = cDe; r = cde; r’ = Cde; r’’ = cdE.
You’re given a phenotype: D+, C+, E-, c-, e+. What antigens must be present on at least one chromosome? D, C, and e must be present on at least one chromosome.
You’re given a phenotype: D+, C+, E-, c-, e+. What antigens must be absent on both chromosomes? E and c must be absent on both chromosomes.
You’re given a phenotype: D+, C+, E-, c-, e+. Walk through how you would narrow to possible haplotype pairs. Only haplotypes with D, C, e and lacking E and c fit: R1 (CDe) and r’ (Cde). Possible pairs: R1/R1 or R1/r’.
What phenotype clue immediately tells you a particular antigen is present on both haplotypes? Very strong (homozygous-looking) expression—consistently strong reactions suggesting the antigen is on both chromosomes.
Describe a testing pattern that suggests weak D (what’s negative vs positive, and at what phase?). Negative at immediate spin and 37°C, but positive with anti-D at the AHG phase.
Why do we care about weak D status differently for patients vs donors? Patients are treated as D-negative to avoid sensitization; donors are labeled D-positive so their blood doesn’t immunize D-negative recipients.
If a patient types “D-negative” at IS but becomes positive at AHG, what is the safest blood selection choice and why? Give D-negative blood to avoid the risk of sensitizing the patient to D.
What does a Rh control help you rule out in Rh typing? It helps rule out false positives from autoagglutination or nonspecific serum reactivity.
What does Rhnull mean at the antigen level? What would the typing reactions look like? RBCs lack all Rh antigens; all Rh typing reagents (D, C, c, E, e) would be nonreactive.
Why can Rhnull patients have chronic hemolysis (what’s happening to the RBC membrane)? Rh proteins help stabilize the RBC membrane; without them, the membrane is abnormal and fragile, leading to chronic hemolysis.
What smear finding is often associated with Rhnull? Stomatocytes.
What makes Rhnull clinically challenging when the patient needs transfusion support? They can only safely receive Rhnull blood, which is extremely rare.
What is the key relationship between LW and Rh(D) expression? LW antigen expression is stronger on D-positive cells than on D-negative cells.
Why can LW confuse someone who’s trying to interpret Rh antibody behavior? Anti-LW can mimic anti-D because it reacts more strongly with D-positive cells, making it look like an anti-D pattern.
Where are Lewis antigens made, and how do they end up on RBCs? They are made in tissues and secretions, then adsorb onto the surface of red blood cells from plasma.
Why are newborns typically typed as Le(a-b-) early in life? Lewis antigens are not fully developed at birth, so newborns appear Le(a-b-).
You see the phenotype Le(a-b+). What does that imply about secretor status and the Lewis gene pathway (conceptually)? It implies the person is a secretor with a functional Lewis pathway, producing Leb that adsorbs onto RBCs.
Lewis antibodies often show what temperature phase pattern (cold/warm), and why does that usually matter clinically? They are usually cold-reactive IgM, so they rarely cause clinical problems and are generally considered insignificant.
Why is the Kell system often taught as the “next most important” after Rh? Because anti-K is common and can cause severe HDFN and significant transfusion reactions.
What is the association between McLeod phenotype and Kell-related antigen expression (what’s missing/abnormal)? McLeod phenotype has reduced or absent Kell expression due to missing or abnormal Kx protein.
If a patient has anti-K, what is your blood selection plan (in plain language)? Select K-negative red blood cell units for transfusion.
Which Duffy phenotype is associated with resistance to Plasmodium vivax, and what is the “why” (what can’t the parasite do)? Fy(a-b-) phenotype; P. vivax cannot attach to or enter the RBCs because the Duffy receptor is missing.
In antibody workups, how do enzymes affect Duffy antigens and why is that a useful clue? Enzymes destroy Duffy antigens, so Duffy-related reactions disappear after enzyme treatment—this helps identify Duffy antibodies.
What is the difference between I and i antigen expression in newborns vs adults? Newborns have mostly i antigen; adults have mostly I antigen.
How does that developmental switch connect to cold autoantibodies like anti-I (big concept, not detail)? Cold auto-anti-I reacts strongly with adult cells (I+) but weakly with newborn cells (i+), which helps explain its pattern.
What is the purpose of enzyme-treated cells in an antibody investigation? To see which antigens are destroyed or enhanced, helping narrow down which antibody is present.
Name two blood group system antigens that are commonly destroyed by enzymes and explain how that changes reactions. Duffy and M/N antigens are destroyed by enzymes, so antibodies to them lose or weaken their reactions after enzyme treatment.
Name two systems that are commonly enhanced by enzymes and what that suggests when reactions get stronger post-enzyme. Kidd and Lewis (and Rh) are enhanced by enzymes; stronger reactions after enzymes suggest antibodies from these systems.
If reactions disappear after enzyme treatment, what “bucket” of antibodies jumps up your differential and why? Duffy and M/N antibodies, because their target antigens are destroyed by enzymes, causing loss of reactivity.
Why don’t we do reverse typing for D the way we do for ABO? Because anti-D is not naturally occurring; people don’t normally have anti-D in their plasma without prior exposure.
Describe the two real-life ways a person can form anti-D. Exposure to D-positive red cells through pregnancy with a D-positive fetus or transfusion with D-positive blood.

Created by: user-2027432

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