1/80
81 vocabulary flashcards covering key terms, antigens, antibodies, phenotypes, tests and discrepancies discussed in the Immunohematology seminar.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
Immunohematology
Serologic, genetic, biochemical and molecular study of blood-cell antigens and their immune reactions.
Transfusion Medicine
Multidisciplinary specialty covering blood donation, component preparation, serology and clinical transfusion therapy.
Blood Banking
Branch of transfusion medicine focused on testing, storing and issuing compatible blood to optimize patient outcomes.
ABO Blood Group
Most immunogenic carbohydrate blood-group system; antibodies form naturally and are critical in transfusion compatibility.
Rh Blood Group
Protein antigen system discovered by Landsteiner & Wiener; D antigen is highly immunogenic and routinely typed.
Karl Landsteiner
Discovered the ABO blood group system in 1901, explaining causes of incompatible transfusions.
William Harvey
Rediscovered systemic blood circulation in 1628, laying groundwork for transfusion science.
Hemolytic Disease of the Fetus and Newborn (HDFN)
Maternal IgG antibodies cross placenta and destroy fetal red cells, causing anemia and hyperbilirubinemia.
Antiglobulin Test (Coombs’ Test)
Assay using anti-human globulin to detect IgG or complement bound to red cells.
Direct Antiglobulin Test (DAT)
One-step AHG test that detects in vivo-coated red cells with IgG and/or complement.
Indirect Antiglobulin Test (IAT)
Two-step AHG test that detects in vitro-sensitized red cells in antibody screening, identification and crossmatch.
Alloantibody
Antibody produced against antigens not present on the producer’s own cells.
Autoantibody
Antibody that reacts with antigens on the individual’s own red cells.
IgM
Pentameric, naturally occurring, cold-reactive antibody class; best complement activator.
IgG
Monomeric antibody reacting at 37 °C, crosses placenta, causes extravascular hemolysis.
Forward Grouping
ABO typing that detects antigens on patient RBCs using known antisera.
Reverse Grouping
ABO typing that detects serum antibodies with reagent A1 and B red cells.
Rouleaux Formation
Stacking of red cells due to increased plasma proteins, mimicking agglutination.
Lectin
Plant protein that specifically agglutinates certain blood groups (e.g., Dolichos biflorus for A1).
Gel Technology
Method where agglutinated red cells are trapped in dextran-acrylamide gel microtubes after centrifugation.
H Antigen
Precursor molecule on which A and B antigens are built by specific transferases.
FUT1 Gene
Chromosome 19 gene encoding α-1,2-L-fucosyltransferase that forms H antigen on red cells.
Secretor (Se) Gene
FUT2 allele that allows expression of ABH substances in body secretions.
Bombay Phenotype (Oh)
hh genotype lacking H antigen; serum contains anti-A, anti-B, anti-AB and potent anti-H.
Para-Bombay Phenotype
Rare phenotype with minimal or absent H antigen on RBCs but ABH substances may be secreted, depending on FUT1/FUT2 status.
A1 Subgroup
Common A phenotype reacting with anti-A and anti-A1; ~1 million antigen sites per cell.
A2 Subgroup
A phenotype reacting with anti-A but not anti-A1; fewer antigen sites and more detectable H antigen.
Weak A Subgroup
Phenotypes with greatly reduced A antigen expression, variable agglutination and strong anti-H reaction.
Anti-A1
Naturally occurring IgM found in some A2/A2B persons; reacts with A1 cells and seldom causes transfusion issues.
Anti-H
IgM antibody targeting H antigen; strong in Bombay sera, weak in some A1 individuals.
ABO Discrepancy Group I
Reverse-grouping problem due to weak or missing serum antibodies.
ABO Discrepancy Group II
Forward-grouping problem caused by weak or missing red-cell antigens.
ABO Discrepancy Group III
Forward and reverse issues produced by plasma abnormalities, leading to rouleaux/pseudo-agglutination.
ABO Discrepancy Group IV
Miscellaneous typing problems such as cold autoantibodies, polyagglutination or cis-AB.
Fisher-Race Nomenclature
Rh terminology using D, C/c and E/e to denote three closely linked genes.
Weiner Nomenclature
Rh terminology representing complex agglutinogens (e.g., R0, R1, r) encoded by a single locus.
Weak D
Reduced D antigen density requiring IAT for detection; individuals type Rh-positive for transfusion.
Partial D (Mosaic D)
Phenotype missing portions of the D antigen; affected individuals may form anti-D.
Del Phenotype
Extremely low D antigen expression detectable only by adsorption–elution methods.
Rh Null
Absence of all Rh antigens, usually due to RhAG defects; associated with stomatocytosis and hemolytic anemia.
Rh-Associated Glycoprotein (RhAG)
Membrane co-expressor required for surface display of Rh proteins; absence causes Rh null phenotype.
f Antigen (ce)
Compound antigen expressed when c and e are inherited on the same chromosome.
G Antigen
Epitope present on most D-positive or C-positive RBCs; anti-G mimics anti-D + anti-C.
Coombs’ Control Cells
IgG-sensitized red cells added to negative AHG tests to confirm reagent activity.
Hemolytic Transfusion Reaction (HTR)
Immune destruction of transfused RBCs by recipient antibodies; may be acute or delayed.
Kleihauer-Betke Test
Acid-elution smear quantifying fetal RBCs in maternal blood to calculate RhIg dose.
RhoGAM
Concentrated anti-D immune globulin given to Rh-negative mothers to prevent Rh immunization.
Lewis Blood Group
Fucosylated antigens produced in tissues and adsorbed onto RBCs; phenotypes depend on Le and Se genes.
Anti-Lea
Naturally occurring IgM that can fix complement and occasionally hemolyze transfused RBCs.
MNS Blood Group
Glycophorin-based antigens (M, N, S, s, U) showing dosage and sensitivity to proteolytic enzymes.
Anti-M
Usually IgM, pH-dependent antibody that often shows dosage and rarely causes HDN.
P Blood Group
System containing P, P1 and Pk antigens; antibodies include anti-P1 and Donath–Landsteiner anti-P.
Donath–Landsteiner Antibody
Biphasic IgG anti-P that causes paroxysmal cold hemoglobinuria.
I Blood Group
Developmental system in which newborns are i-positive and adults I-positive.
Autoanti-I
Cold autoantibody often associated with Mycoplasma pneumoniae infection and cold agglutinin disease.
Kell Blood Group
Highly immunogenic protein system; K antigen ranks second to D in clinical importance.
McLeod Phenotype
X-linked absence of Kx antigen with weakened Kell expression and acanthocytosis; linked to chronic granulomatous disease.
Duffy Blood Group
Fy antigens serve as receptors for Plasmodium vivax; Fy(a-b-) individuals resist infection.
Kidd Blood Group
Urea-transporter antigens Jka/Jkb; antibodies cause notorious delayed hemolytic transfusion reactions.
Jk(a-b-) Phenotype
Rare Kidd-null red cells resistant to 2 M urea lysis; may produce anti-Jk3.
Lutheran Blood Group
Poorly developed Lua and Lub antigens; anti-Lub may shorten survival of transfused cells.
Cold Reacting Antibody
Usually IgM; agglutinates best at or below room temperature (22–25 °C).
Warm Reacting Antibody
Usually IgG; reacts optimally at body temperature (37 °C).
PEG (Polyethylene Glycol)
Enhancement medium that concentrates antibodies by removing water during IAT.
DTT (Dithiothreitol)
Sulfhydryl reagent used to break IgM pentamers or treat RBCs to eliminate IgM-mediated agglutination.
Chimerism
Presence of two genetically distinct red-cell populations in one individual.
Polyagglutination
Exposure of crypt antigens on RBCs causing universal agglutination with most adult sera.
Acquired B Phenomenon
Bacterial de-acetylation of A antigen, transiently making group A cells react with anti-B sera.
Hydatid Cyst Fluid
Source of soluble P1 substance used to neutralize anti-P1 antibodies.
Stomatocyte
Cup-shaped red cell commonly seen in Rh null phenotype.
Kleihauer Betke Percentage
% Fetal cells = (fetal cells ÷ total RBCs) × 100; used to estimate fetomaternal hemorrhage.
MicRhoGAM
50 µg dose of anti-D immunoglobulin for Rh-negative women with first-trimester pregnancy events.
Paroxysmal Cold Hemoglobinuria (PCH)
Hemolytic anemia triggered by cold; mediated by Donath–Landsteiner antibodies against P antigen.
Co-dominant
Genetic expression in which both alleles are fully manifested, e.g., Lutheran Lua and Lub.
Dosage Effect
Stronger antibody reactions with homozygous antigen expression than with heterozygous cells.
Enzyme-treated Cells
RBCs exposed to proteases; enhance some antigens (Rh, Kidd) and destroy others (Duffy, MNS).
ISBT Number
Six-digit standardized code assigned to each blood-group antigen (e.g., 004001 = D).
Agglutinogen
Complex of antigens encoded by a single locus in Weiner Rh nomenclature.
Glycosyltransferase
Enzyme that adds specific sugar residues to precursor chains, forming blood group antigens.
Complement Fixation
Activation of complement cascade by antigen-antibody complexes, potentially leading to hemolysis.
Alloimmunization
Immune response to foreign blood-group antigens after transfusion or pregnancy, producing alloantibodies.