Blood Banking Reagents Flashcards
Routine Testing procedures
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
ABO/D typing (forward grouping)
purpose: detects A, B, D antigens
source of antigens : patients RBC
source of antibody : commercial anti -A, anti-B, anti-D
ABO serum testing (reverse grouping)
purpose: detects ABO antibodies
source of antigen : reverse grouping cells (A1 & B1)
source of antibody : patient’s serum or plasma
Antibody Screen
purpose : detects antibodies w/ specificity to RBC antigens
source of antigen : screening cells
source of antibody: patient’s serum or plasma
Antibody ID
purpose: IDs specific of RBC antibodies
source of antigen: panel cell
source of antibody: patient’s serum or plasma
Crossmatch
purpose: determines serological compatibility between donor & patient before transfusion
source of antigen: donor’s RBCs
source of antibody: patient’s serum or plasma
Can one use expired reagents in the blood bank lab?
yes for rare antisera & selected reagent RBC
no - ALL OTHER COMMON REAGENTS FOR ROUTINE TESTING
quality control procedures in blood bank lab
must test the reactivity of every reagent used that day:
- mix a reaction that is known to be positive (E RBC & anti-E antisera)
- mix a reaction that is known to be negative (E- RBC and anti-E antisera)
Polyclonal Reagents
derived from animals, contains several clones of B-cell antibody
Monoclonal Reagents
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
Reagents for ABO antigen typing
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
Reagents for Rh Antigen typing
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
Anti-human globulin (AHG) reagents
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
Check cells or Coombs Cells
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
screening cells
used in antibody screen tests
obtained from O type
available as 2 or 3 vial sets
detects the ‘most clinically relevant significant antibodies’
Panel cells
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
Potentiator purpose
used in indirect antiglobulin testing
speeds/enhances antibody-antigen interaction
allows detection of lower levels/weaker antibodies
LISS (low ionic strength solution)
enhances antibody uptake by reducing ionic strength of environment - decreases [Na+] = decreases zeta potential
still isotonic - contains NaCl, glycine, albumin
BSA (Bovine Serum Albumin)
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
PEG (Polyethylene Glycol)
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
Proteolytic enzymes (proteases)
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
Lectins
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
Gel Technology methods (ortho)
uses acrylamide gel particles to trap agglutinated RBC
used for ABO, D, Rh typings, antibody screen, antibody ID, compatibility testing & DAT
reading ortho gel cards
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
