c. With the exception of very rare antigens, identification should include tests
with a minimum of three cells containing the antigen, and three cells lacking the antigen.
The serum should react as expected with the six cells. Six cells reacting three negative
and three positive provides a probability of 1/20 that the specificity is correct, with only
one chance in 20 that the reactions could have occurred by chance. Probability of less
than 1/20 allows for too much chance of random association. Table 1-3 gives
Number of Cell Samples
Reactions*
Positive
Negative
P
6
4
2
1/15
6
3
3
1/20
7
5
2
1/21
7
4
3
1/35
8
7
1
1/8
8
6
2
1/28
8
5
3
1/56
8
4
4
1/70
9
8
1
1/9
9
7
2
1/36
9
6
3
1/84
9
5
4
1/123
10
9
1
1/10
10
8
2
1/45
10
7
3
1/120
10
6
4
1/210
10
5
5
1/252
* No discrepancies.
Table 1-3. Probability of identity with panels of various sizes.
d. The cells of the sample should be tested with the proper reagent serum to
show they lack the incriminated antigen.
(1)
Example: Antibody detection. Table 1-4.
MD0846
1-41