Exam 1 Flashcards
What is the main method used to screen for viruses in donor blood?
Nucleic Acid Testing
What viruses are screened for in donor blood?
West Nile Virus HIV HCV HTLV-1 HBV Syphilis Trypanosoma cruzi
What are the three areas that are crucial for normal RBC function and 120 day survival?
- Normal composition and structure of membrane
- Hgb structure and function
- RBC metabolism
What type of metabolism does the RBC membrane perform?
Anaerobic
Normal hemoglobin consists of what chains?
Two alpha and two beta
What is the primary function of hemoglobin?
Primary function is oxygen delivery to tissues and carbon dioxide excretion
What is the most important control of hemoglobin affinity?
2,3-DPG
When 2,3-DPG is bound what form is the hemoglobin in and what happens to oxygen affinity?
Tense; decreases oxygen affinity
When 2,3-DPG is not bound, what state is hemoglobin in and what happens to oxygen affinity?
Relax; Increases oxygen affinity
What causes a right shift in the hemoglobin dissociation curve?
Increased 2,3-DPG
Increased temperature
Acidosis (decreased pH)
What causes a left shift in the hemoglobin dissociation curve?
Alkalosis Methemoglobin and carboxyhemoglobin Increased hemoglobin F 2,3-DPG depleted stored blood Decreased temperature
Lesion of storage
Decrease in pH, buildup of lactic acid, decrease in glucose consumption, decrease in ATP, loss of RBC function, decrease in 2,3-DPG
What temperature should RBCs be stored at?
1-6 C
ACD; CPD, CP2D preservation days
21 days
CPDA-1 preservation days
35 days
Additive solutions (Adsol, Nutricel, Optisol) preservation days
42 days
Do additive solutions affect 2,3-DPG levels?
No
How do Polyvinyl chloride plastic bags help RBC storage?
Permeable to CO2 to maintain higher pH levels
What is the purpose of RBC freezing?
Used for autologous and rare blood types
What is added to RBCs when freezing?
Cryoprotective agent
What must be done to frozen RBCs before transfusing?
Deglycerolized
What antigens are present on platelets?
ABO antigens but not Rh
Platelet concentrate minimums
5.5*10^10
45-65 mL
pH 6.2
Platelet concentrate storage
5 days at 20-24 C
Plateletpheresis minimum
3.0*10^11
What are the advantages of plateletpheresis over platelet concentrate?
One donor
Decreases platelet refractoriness
What happens to the following measurements during storage of RBCs:
- pH
- 2,3-DPG
- ATP
- Plasma K+
- Decreases
- Decreases
- Decreases
- Increases
Affinity
Strength of a single antibody-antigen bond
Avidity
Binding strength of multivalent antigen with antisera
Valency
Number of antigen-binding sites on an antibody molecule
Prozone
Antibody excess
Postzone
Antigen excess (correct with increased serum)
Zeta potential
Difference in electrostatic potential of net negative charge surrounding RBCs and positive charge of surrounding cations, allowing agglutination
Which antibodies are enhanced by enzymes?
Rh, Jk, P1, Le, I
Which antibodies are suppressed by enzymes?
Fy, M, N, S
Gene
Section of DNA along a chromosome which codes for a product
Locus
Specific location of a gene on a chromosome
Southern blotting
DNA
Northern blotting
RNA
Western blotting
Proteins
In PCR, what are the primers mixed with?
Target sequence, Taq DNA polymerase, dNTPs, magnesium
Nucleic acid testing enables us to….
Quantify DNA and is highly sensitive
What is the most important test in blood bank for the detection of clinically significant antibodies?
Anti globulin test
If the patient had a transfusion, what could be the two possible causes of a positive DAT?
Recipient alloantibody against donor antigen
Donor antibody reacts against recipient antigen
Look up positive DATs
Drug induced
Autoimmune hemolytic anemia
Paroxysmal cold hemoglobinuria
HDN
Causes for a false positive AHG test
Refrigeration Autoagglutinable cells Bacterial contamination Saline contamination Overcentrifugation Contaminating abs in AHG reagent
Causes for false negatives
Inadequate washing of cells AHG reagent nonreactive AHG reagent not added Inadequate incubation Undercentrifuged Poor reading
ABO Type I Chain
1 –> 3 linkage ; carry free floating antigens
ABO Type II chain
Beta 1–> 4 linkage; carry RBC bound antigens
Greatest amount of H
O > A2 > B > A2B > A1 > A1B
Which plant lectin agglutinates H antigen?
Ulex Europeaus
What is the most common blood group? What is the least common?
O; AB
When secretors add the H antigen, what is added onto the type I chain?
Fucose to the terminal galactose
What does the A gene code for?
N-acetyl-D-galactosamine sugar to the H substance
A1 cells lectin
Dolichose biflorus
A2 cell lectin
Ulex Europaeus
B gene codes for…
D-galactose sugar to the H substance
A1 has higher or lower concentrations of the enzyme
Higher
Acquired B phenomenon
A1 patients react with anti-B
What syndrome is characterized by intestinal obstruction, cancer increasing permeability of wall allowing passage of bacteria?
Acquired B phenomenon
Isoagglutinins
Weak or absent in hypogammaglobulinemia
What causes ABO discrepancies?
Inadequate identification Cell suspension too light or heavy Clerical Mix up in samples Missed hemolysis Failure to add reagents Contamination Warming during centrifugation
Group I Discrepancies
Unexpected reactions in the reverse groupings because of weakly reacting or missing antibodies due to depressed antibody production
Group 1 Discrepancies solution
Incubate reverse type 15-30 minutes
Group II Discrepancies
Associated with unexpected reactions in the forward groupings due to weakly reacting or missing antigens (acquired B phenomenon)
Group III Discrepancies
Between forward and reverse groupings caused by protein or plasma abnormalities that result in Rouleaux formation
Group IV Discrepancies
Cold reactive antibodies; circulating RBCs of more than one ABO group, Unexpected non-ABO alloantibodies; Unexpected ABO isoagglutinins
R
D
r
d
1 or ‘
C
2 or ‘’
E
0 or blank
ce
DCE
Rz
DCe
R1
DcE
R2
Dce
R0
dce
r
dCe
r’
dcE
r’’
dCE
r^y
What is the most common Rh frequency in whites?
DCe/dce (R1r)
What is the most common Rh frequency in blacks?
Dce/dce (R0r)
Frequency of R1, R2, R0, r in whites?
R1 > r > R2 > R0
Frequency of R1, R2, R0, r in blacks?
R0 > r > R1 > R2