Test panel: 50 to 100 sets of lymphocytes from HLA-typed individuals, often in wells of a microtiter plate. The test requires adequate complement.
Positive control: uses sera containing known cytotoxic antibodies:
(1) indicates that the testing system worked properly, with adequate complement
(2) can be used as a guide for grading positive reactions
(3) a negative reaction indicates unreliable or invalid test results
Negative control: uses sera lacking cytotoxic antibodies:
(1) standard for assessing cell viability in the test system
(2) a positive reaction indicates invalid testing (poor technique, carryover, etc.)
The ASHI recommended scoring system:
|
percentage dead lymphocytes
|
interpretation
|
score
|
|
|
not readable
|
0
|
|
0 – 10%
|
negative
|
1
|
|
11 – 20%
|
doubtful negative
|
2
|
|
21 – 50%
|
weak positive
|
4
|
|
51 – 80%
|
positive
|
6
|
|
81 – 100%
|
strong positive
|
8
|
Panel Reactive Antibody (PRA) = percent of wells in the testing tray showing positive reactions, which serves as a measure of the breadth of reactivity.
Interpretation:
• By analyzing the pattern of cells that are positive (lyzed) the specificity of the antibody to HLA antigens can be determined.
Modifications:
(1) addition of anti-human globulin (AHG-augmented LCT)
(2) double addition of serum
