Type&Screen

Question 1

IgG

Answer 1

Monomer
Most common Abs
Cross placenta
Bind complement 
Leads to phagocytosis
4 subclasses: IgG1-4
IgG1: Fixed complement, 23 days, bind macrophage via Fc
IgG3: Fixed complement, 8 days, bind macrophage via Fc

Question 2

Complement pathway

Answer 2

• Classic: via C1, triggered by IgM, IgG
• Alternative: low grade, constant, via C3. Normal: inactive bound C3 via DAF (CD55). Abnormal: Paroxymal Nocturnal Hemoglobinuria
• Lectin: via sugar, no need C1

Question 3

Landsteiner’s law

Answer 3

Have antigen, shouldn’t have antibody

Question 4

Define “naturally occurring”

Answer 4

• Immune exposure to the environment (bacteria, pollen)
• Not require exposure to blood transfusion
• Noticeable 3-6 months

Question 5

Isoagglutination

Answer 5

IgM, IgG, IgA
Cause hemolysis by fixing complement
At RT (due to IgM)

Question 6

Where ABO?

Answer 6

RBC, WBC, PLT
endothelium
epithelium
secretion

Question 7

How much blood can cause an acute hemolytic transfusion reaction

Answer 7

10mL

Question 8

Anti-A,B

Answer 8

Produced by group O –> react A or B cells
Mostly IgG –> cross placenta
Cause ABO HDFN (Hemolytic Disease Fetus & Newborn)

Question 9

ABO genetic

Answer 9

H, h: chromosome 19
A,B,O: chromosome 9
* O = amorph: enzyme produced has no function

Question 10

Precursor chains

Answer 10

Type 1: 1-3 terminal galactose & N-acetylglucosamine
Secretion & Plasma

Type 2: 1-4 terminal galactose & N-acetylglucosamine
RBC & tissue

Question 11

H-antigen

Answer 11

HH or Hh
a-2-L-fucosyltransferase: bring L-fucose to terminal galactose
Amount of H: O>A2>B>A2B>A1>A1B

Question 12

A-antigen

Answer 12

AO, AA, AB
a-3-N-acetyl-D-galactoseamyltransferase: bring N-acetyl-D-galactosamine to terminal Galactose
Requires L-fucose

Question 13

B-antigen

Answer 13

BO, BB, AB
a-3-D-galactosyltransferase: bring D-galactose to terminal galactose
Requires L-fucose

Question 14

Bombay

Answer 14

Lack of H antigen –> hh –> Denote: Oh
Plasma contains all types of Abs: anti-A, anti-B, anti-A,B, anti-H
Cause AHTR
Able to pass on A and B genes

Question 15

ABO in newborns

Answer 15

• Weak expression –> no isoagglutination until 4 months –> No reverse test
• Maternal Abs can cross and attach to baby’s RBC –> no severe as weak ABO

Question 16

FWD testing

Answer 16

• Antigen?: Pt’s RBC + known Abs
• Routinely test with monoclonal IgM (anti-A, anti-B, anti-D)
• AB group requires control to R/O autoagglutination (Control: neg)

Question 17

RVS testing

Answer 17

• Antibody (IgM)? Pt’s plasma + pool A1/B
• Routinely test with A1 cells, B cells
• Perform at Immediate Spin
• No test for D

Question 18

Gel card

Answer 18

FWD: Pt’s RBC + gel with Ab –> Trapped: Pos/Pellet: Neg
RVS: Pt’s plasma + cells –> Trapped: Pos/Pellet: Neg
Mix field: May been seen in FWB when pt had a transfusion in the past.
Pro: stable vs Cons: spin 10min

Question 19

Stage of Agglutination

Answer 19

1. Sensitization: Ab & Ag mix and bind
2. Lattice formation: Abs cross-linking and bind multiple cells
   Happen at the same time: IgM
   Happen at different times: IgG

Question 20

Potentiators

Answer 20

Time, Temp, Medium, Conc, pH, enzymes

Question 21

Prozone

Answer 21

Too much plasma –> excess abs

Question 22

Postzone

Answer 22

Too less plasma –> excess antigen

Question 23

Zeta potential

Answer 23

Negative charge surrounding RBC to keep them away from each other

Question 24

Enhancement

Answer 24

Standard: 37C, 30-60min
Decrease zeta potential by
- LISS: 0.2% saline --> 37C, 5-15 min
- Albumin: 22% --> 37C, 15-60 min
Dry out RBC: PEG --> bring cells closer --> 37C, 10-30 min

Question 25

Gel card pro & cons

Answer 25

Pro: smaller, no washing, clear, stable, can be automated Cons: Expensive

Question 26

Solid-phase pro & cons

Answer 26

Pro: reduce volume, increase sensitivity, less skilled Cons: Expensive, reagent expired, learning curve (?)

Question 27

Direct Antiglobulin Test

Answer 27

Does pt have Ab and/or Complement stuck on RBC/ In vivo Pt's RBC + AHG

Question 28

Indirect Antiglobunlin Test

Answer 28

Does pt have Ab that could bind RBC? In vitro only Pt's plasma + Known screening cells

Question 29

IgD

Answer 29

Found on B cells (play role in B cell development) | Low level in serum

Question 30

IgE

Answer 30

Allergic reaction | Can cause allergic transfusion rxn. Med is ok

Question 31

IgA

Answer 31

Found in milk and secretion Monomer or Dimer IgA deficiency can develop anti-IgA --> Anaphylatic reaction

Question 32

IgM

Answer 32

Pentamer (J chain) First Abs made when exposure Fixes complements React at cold temp.

Question 33

Haplotype

Answer 33

Group of genes inherited together due to close physical location E.g: DCEce, MNSs Rare blood tend to run in families