Defining ELISpot cut-offs from unreplicated test and control wells
Neal Alexander, Annette Fox, Thi Kim Lien Vu, Tao Dong, Laurel Yong-Hwa Lee, Le Khanh Hang Nguyen, Quynh Mai Le, Peter Horby
Journal of Immunological Methods | ELSEVIER SCIENCE BV | Published : 2013
In the absence of replication of wells, empirical criteria for enzyme-linked immunospot (ELISpot) positivity use fixed differences or ratios between spot forming units (SFU) counts between test and control. We propose an alternative approach which first identifies the optimally variance-stabilizing transformation of the SFU counts, based on the Bland-Altman plot of the test and control wells. The second step is to derive a positivity threshold from the difference in between-plate distribution functions of the transformed test and control SFU counts. This method is illustrated using 1309 assay results from a cohort study of influenza in Vietnam in which some, but not all, of the peptide pools..View full abstract
Awarded by United Kingdom Medical Research Council
Awarded by United Kingdom Wellcome Trust
Awarded by European Union FP7 project "European Management Platform for Emerging and Re-emerging Infectious Disease Entities (EMPERIE)"
Awarded by Medical Research Council
This work was supported financially by the United Kingdom Medical Research Council grant number G7508177 to the Tropical Epidemiology Group and by the United Kingdom Wellcome Trust (grants 081613/Z/06/Z and 087982/Z/08/A). AF was supported by the European Union FP7 project "European Management Platform for Emerging and Re-emerging Infectious Disease Entities (EMPERIE)" (no. 223498).