Table 1 Validation of LOD and confirmatory cut point.

From: Validation of an IFN-gamma ELISpot assay to measure cellular immune responses against viral antigens in non-human primates

LOD determination—Mean and ratio

Mean DMSO responses

Confirmatory response ratios

Mean SFU/well

Response ratios: antigen vs DMSO

Donor ID (n = 18)

Triplicate mean SFU/well

Triplicate mean SFU (log 10 transformed)

AAV5 pool 1/mock

AAV5 pool 2/mock

Transgene-product peptide pool/mock

1

2

0.368

1.000

0.714

0.857

2C

1

0.000

3.000

1.333

1.667

3D

1

0.000

0.000

1.333

2.333

4

1

0.125

1.000

0.250

1.000

5

14

1.146

1.643

1.500

0.952

6

10

1.000

1.600

1.133

1.367

7A

71

1.851

1.164

1.192

1.169

8

5

0.699

1.067

1.067

1.000

9

3

0.523

1.700

1.700

1.000

10B

1

0.125

2.500

3.750

4.750

11

5

0.727

0.813

1.000

1.125

12

2

0.222

1.000

1.400

1.400

13

9

0.938

1.038

0.577

1.731

14

11

1.041

1.091

0.970

0.727

15

4

0.602

0.917

1.083

1.417

16

8

0.885

1.000

0.826

1.000

17

2

0.368

0.857

0.286

1.143

18

5

0.669

0.286

0.643

0.643

Minimum

 

0

  

0

25% percentile

 

0.17

  

0.857

Median

 

0.60

  

1.000

75% percentile

 

0.91

  

1.333

Maximum

 

1.15

  

1.731

Mean

 

0.56

  

1.049

Std. deviation

 

0.38

  

0.387

LOD determination (normal distrib.)

  

Confirmatory cut point determination

Mean + 1.645x StDev

1.175

 

Mean +1.645x StDev

 

LOD (Anti-log of above)

15.0

   

1.69

  1. Bold numbers represent the final calculated value for LOD and confirmatory cut point ratio respectively.
  2. LOD and confirmatory cut point were based on a statistical analysis of the mean responses (SFU/well) under unstimulated (mock) conditions and the antigen/mock response ratios in naive monkeys, respectively. One result (7A (71)) was identified as a statistical outlier and excluded from the LOD analysis. Response ratios were obtained by dividing the triplicate mean SFU/well responses for AAV5 or transgene-product (TGP) peptide pools by the respective triplicate mean SFU/well response under unstimulated conditions (i.e., peptide stimulation/mock control). Five response ratios (2C (3.000), 3D (2.333) and 10B (2.500, 3.750 and 4.750)) were identified as statistical outliers and excluded from the confirmatory cut point analysis.