Blood Banking Reagents

Question 1

Routine Testing procedures

Answer 1

forward typing - ABO & D typing for antigens on RBCs
serum/plasma testing for antibodies (reverse typing)
antibody screen - pregnancy & transfusions
antibody ID
crossmatch - RBC donor unit & recipient patient plasma

Question 2

ABO/D typing (forward grouping)

Answer 2

purpose: detects A, B, D antigens
source of antigens : patients RBC
source of antibody : commercial anti -A, anti-B, anti-D

Question 3

ABO serum testing (reverse grouping)

Answer 3

purpose: detects ABO antibodies
source of antigen : reverse grouping cells (A1 & B1)
source of antibody : patient’s serum or plasma

Question 4

Antibody Screen

Answer 4

purpose : detects antibodies w/ specificity to RBC antigens
source of antigen : screening cells
source of antibody: patient’s serum or plasma

Question 5

Antibody ID

Answer 5

purpose: IDs specific of RBC antibodies
source of antigen: panel cell
source of antibody: patient’s serum or plasma

Question 6

Crossmatch

Answer 6

purpose: determines serological compatibility between donor & patient before transfusion
source of antigen: donor’s RBCs
source of antibody: patient’s serum or plasma

Question 7

Can one use expired reagents in the blood bank lab?

Answer 7

yes for rare antisera & selected reagent RBC

no - ALL OTHER COMMON REAGENTS FOR ROUTINE TESTING

Question 8

quality control procedures in blood bank lab

Answer 8

must test the reactivity of every reagent used that day:

1. mix a reaction that is known to be positive (E RBC & anti-E antisera)
2. mix a reaction that is known to be negative (E- RBC and anti-E antisera)

Question 9

Polyclonal Reagents

Answer 9

derived from animals, contains several clones of B-cell antibody

Question 10

Monoclonal Reagents

Answer 10

produced in vitro
a created clone that contains 1-2 antibodies of a defined specificity
IgM monoclonals are more prevalent bc of speed of reactions

Question 11

Reagents for ABO antigen typing

Answer 11

commercial sera produced
anti-A (blue dye): single IgM monoclonal
Anti-B (Yellow Dye): single IgM mono
Anti-A,B: 2 IgM monos verry sensitive to subclasses of A

Question 12

Reagents for Rh Antigen typing

Answer 12

D is the most important Rh antigen in routine blood bank testing
most labs use monoclonal blend:
1 IgM mono
1 IgG mono for weak D at 37

Question 13

Anti-human globulin (AHG) reagents

Answer 13

polyspecific AHG primarily in DAT & contain antibodies to both IgG & C3b,d
monospecifc AHG is an IgM mono against IgG
anti-C3b,d is an IgM mono

Question 14

Check cells or Coombs Cells

Answer 14

commercially prepared O cells that have been sensitized w/ anti - D IgG
ensures all negative AHG tests that in fact AHG was added, cells were sufficiently washed, & AHG would be able to react
ALWAYS GIVE A POSITIVE REACTION

Question 15

screening cells

Answer 15

used in antibody screen tests
obtained from O type
available as 2 or 3 vial sets
detects the ‘most clinically relevant significant antibodies’

Question 16

Panel cells

Answer 16

used to determine the specificity of an antibody when an antibody screen detects the presence of an unexpected antibody
uses type O blood
packaged in sets of 10 + vials
antigenic profile of each donor is included

Question 17

Potentiator purpose

Answer 17

used in indirect antiglobulin testing
speeds/enhances antibody-antigen interaction
allows detection of lower levels/weaker antibodies

Question 18

LISS (low ionic strength solution)

Answer 18

enhances antibody uptake by reducing ionic strength of environment - decreases [Na+] = decreases zeta potential
still isotonic - contains NaCl, glycine, albumin

Question 19

BSA (Bovine Serum Albumin)

Answer 19

allows antibody-sensitized cells to come closer together than is possible in saline suspension
enhances 2nd stage of agglutination
22% solution of BSA
often not used bc it takes approx ~30 min

Question 20

PEG (Polyethylene Glycol)

Answer 20

in a low ionic strength medium PEG concentrates antibody while enhancing rate of antibody uptake
removes water molecules
must be careful to avoid false positives
DO NOT CENTRIFUGE PEG w/ RBC
most sensitive method for detecting antibodies

Question 21

Proteolytic enzymes (proteases)

Answer 21

papain or ficin or bromelin
break down protein molecules
modifies RBC membrane by removing - charged molecules & decreases zeta potential & denaturing certain antigens 
enhances Rh, Kidd, & Lewis
denatures MNS, Fy

Question 22

Lectins

Answer 22

alternative reagents to antisera for blood typing purposes
derived from plants - no antibodies
bind to CHO residues on certain blood group antigens
Dolichos biflorus - A1
Ulex europeaus - H

Question 23

Gel Technology methods (ortho)

Answer 23

uses acrylamide gel particles to trap agglutinated RBC

used for ABO, D, Rh typings, antibody screen, antibody ID, compatibility testing & DAT

Question 24

reading ortho gel cards

Answer 24

0- red cells filter through gel layer completely and sit at the bottom
4- red cells agglutinate in one clump and none can filter through the gel
MF- mixed fields as in transfusions w/ 2 different populations of RBCs