Blood Bank Exam 1 Flashcards
RBC Membrane is freely permeable to
- Water
- Anions
- O2 and CO2
RBC Membrane is NOT freely permeable to
- Na+
- K+
- Ca2+
Active transport is required, using energy (ATP)
RBCs get their energy from
- 90% from Anaerobic Glycolysis
- 10% from Monophosphate Shunt
Minimum Requirement for pRBC unit viability
75% survival of transfused RBCs after 24 hours
RBC storage temp
1-6°C
One Unit pRBC contains
405-495 mL of blood
63 mL anticoagulant/preservative
WB (Whole Blood) Storage temp
1-6°C
Plasma (FFP) Storage temp
-18°C or below
Platelets Storage temp
20-24°C
Two Stages of Agglutination
1: Sensitization
2: Lattice formation
AHG
Anti-human globulin, added to assist with lattice formation
PEG
Polybrene & Polyethylene Glycol
Zeta Potential
Net negative charge on surface of RBCs. Pushes each other away, resisting lattice formation
ABO Forward Reactions
Using reagent antisera to test for patient antigens
ABO Reverse Reactions
Using reagent cells to test for patient antibodies in serum
ABO Gene Locus
Chromosome 9
Hh Gene Locus
Chromosome 19
Sese Gene Locus
Chromosome 19
Where are blood type antigens found?
On RBCs, epithelial cells and in soluble form in the plasma
“H” gene codes for
fucosyltransferase, adds fucose to CHO (“carbohydrate”) chain, forming the H antigen
h/h Genotype
Bombay blood. No fucose added, no H antigen, no A/B phenotype possible. “Oh” phenotype.
Two types of CHO precursors
Type 1 - Body Fluids, 1-4 linkage
Type 2 - RBCs, 1-3 linkage
“A” gene codes for
N-acetylgalactosaminyl transferase, adds N-acetylgalactosamine to fucose chain, forming the A antigen
“B” gene codes for
Galactosyl transferase, adds galactose to the end of the fucose chain, forming the B antigen
“O” gene codes for
No enzyme (amorph). Fucose remains terminal on the CHO chain, displaying the H antigen
Test for Bombay blood
Anti-H lectin
“Se” gene codes for
Secretion of H, A, and B antigen (in saliva, tears, bile, milk, etc.)
ABO Antibody class from immune exposure
IgG
ABO Antibody class that is naturally occurring
IgM
Antibody productions starts at what age?
3-6 months of life, ignore reverse reactions on cord blood
Discrepancy
When the forward reaction doesn’t match the reverse reaction
In type A and B patients, antibodies to the opposite tend to be
IgM
In type O patients, antibodies to A and B tend to be
IgG
Type A vs Type A2
- Type A has A1 and “A” (A2) antigens
- Type A2 has A2 antigens only
Mixed Field Reaction
Obvious agglutination with a cloudy (unagglutinated) background
Group I Discrepancies
Weakly reacting or missing antibody reactions
- Age
- Immunodeficiency
Group II Discrepancies
Weakly reacting or missing antigens; extra antigens
- disease-related
- acquired B antigens
- Rare antibodies
Group III Discrepancies
Protein/plasma abnormalities
- increased globulins
- increased fibrinogen
- plasma expanders
- Wharton’s Jelly
Group IV Discrepancies
Miscellaneous
- Polyagglutination
- Cold reactive antibodies
- Warm autoantibodies
- Unexpected antibodies
- Unexpected Ag-Ab complexes
- cis AB phenotype
DAT Testing Detects
IN VIVO coating of RBCs with Antibody or C’
IAT Testing Detects
IN VITRO reactions of serum and reagent RBCs (hunting for antibodies)
IgG 1 is best at
crossing the placenta
IgG 4 is least likely to
activate complement
Which AHG reagent isn’t used in routine testing
Anti-C3d,C3b
Common complement binding antibodies
- Anti-A
- Anti-B
- Anti-Jka
- Anti-Lea
Check Cells are added to
negative AHG tubes to confirm it as a true negative (both DAT and IAT)
Rh control is used when
albumin (high protein) reagent is used
Rh control is positive when
DAT is positive
If Check Cells are negative
likely error in wash steps
3 Phases of IAT testing
- RT - detect “cold antibodies” (IgM)
- 37C - detect “warm antibodies” (IgG)
- AHG - detects sensitized cells
Why are albumin reagents falling out of fashion?
Prone to spontaneous agglutination
If you have the D antigen, you are Rh
positive
HDN
Hemolytic Disease of the Newborn
Where is the D antigen found
on RBCs only (integral membrane component)
5 most common Rh antigens
D, C, c, E, e
Tippet/Rosenfield
Rh naming system, is primarily used for research
Fisher Race
Rh naming system, most used, 3 closely linked loci inherited as a unit
Genotype that strengthens expression of D antigen
R2 (cDE)
Cis effect
E antigen weakens when on the same haplotype as D
Trans effect
E and C antigens weaken when on opposite haplotypes from D
Weak D notation
Du
Who is tested for weak D
- Blood donors
- Mom/Baby testing
Anti-G
Anti-C,D; expressed by D neg individuals
LW Antigen
Separate from D antigen, but weaker in D neg individuals
Rh Null
No Rh Antigens (d/d, deletion of C/c and E/e). Very rare
Antibodies to Rh antigens result from
exposure
Rh Antigen Immunogenicity
e < C < E < c < D
Enhancement Media for Rh antibody testing
PEG or LISS
Concomitant Antibodies
Antibodies which often occur together (E and c due to common R1 genotype)
Protein % in albumin reagent
20-24%
Rhi antigen
C,e compound antigen found on DCe haplotype cells (R1 gene)
f antigen
c,e antigen that occurs when c and e are in the same haplotype (Dce)
Frequency of D vs d phenotype
85% D, 15% d
Frequency of C, c, e
70%
Frequency of E
30%
Most common Rh haplotypes
DCe (white, native, asian), dce (white, black), Dce (black)
Most common Rh genotypes for Caucasians
DCe/dce - 33%
DCe/DCe - 18%
dce/dce - 15%
