Practical 6: Unexpected antibodies using enzyme gel Flashcards
When would an enzyme gel be used
Following the finding of a positive Antibody screen
It is used to identify the antibodies involved in the reaction
How is an unexpected antibody identified
This is done by testing the patients plasma against 10-15 different reagent red cells
The test is carried out using normal Liss/Coombs gel cards and an enzyme/NaCl gel card
How do you know which are the normal IAT cells and which are the enzyme treated rbcs?
The enzyme panel has red lids and the normal IAT have white lids
What are the three effects that enzymes can have on antigens
Enhance the reaction
Decrease the reaction
Not affect them at all
What antigens are enhanced by enzyme treatment
(7)
Carbohydrate based antigens
ABO- related antigens
Lewis system
I system
P1PK/GLOB
Rh System
Kidd system
What antigen systems are decreased by enzyme treatment
MNS
Duffy
What antigen systems are unaffected by enzyme treatment
Kell System
Why does enzyme treatment decrease MNS and Fy?
The enzyme cleaves MNS and Fy antigens of the rbc surface
Why is AHG not required in the enzyme treated gel
The enzyme cleaves the MNS and Fy antigens and thus cleaves the rbc charge which allows IgG to crosslink without AHG thus a NaCl gel is used
What is your positive control in the gel panel
Use a weak anti-D and an RhD positive reagent cell
What three antigen systems do you need homozygous expression to exclude them
Duffy
Kidd
M/N/S
