Uid or lyophilized antibodies. Frequencies of CD3+CD4+, CD3+CD8+, CD3+CD4+CD45RO+ (memory CD4+ T cells), CD3+CD8+CD45RO+ (memory CD8+ T cells) and Tregs (CD3+CD4+CD25highFoxP3+) cells were calculated using unstimulated samples, while frequencies of IFN-c+, IL-17A+, or IL-10+ cells were calculated from stimulated samples within memory CD4+ or memory CD8+ T cells. Cell frequencies obtained by LFP and CFP were compared using Bland Altman plots in which the differences between the cell frequencies obtained by the two methods (calculated as CFP minus LFP, y axis) are plotted against the cell frequency averages of the two methods (x axis). Horizontal lines are drawn at the mean difference (bias), and at the limits of agreement, which are defined as the mean difference 61.96 times the SD of the differences. The tables associated with each plot indicate cell frequency mean 6 SD measured by CFP and LFP, and the p value for a paired t test or Wilcoxon signed rank test, **P,0.01, ***P,0.001. B-E. IL-10+ (B,D) and IFN-c+(C,E) cells, within CD4+ and CD8+ memory T cells, are plotted after logarithmic transformation. doi:10.1371/journal.pone.0065485.gwith lyophilized reagents contribute to an increased detection of markers such as IFN-c and IL-10. Taken together these results suggest that LFP has higher sensitivity to detect key cytokines.Lyophilized antibodies result in higher stain index in stained cells compared to Ion, in human genetic studies, IRAK-M has also been associated with Liquid antibodiesNext, we qualitatively compared the performance of liquid and lyophilized antibodies by calculating the stain index (SI) of stained cells, which is a measure of the brightness of a marker and its resolution sensitivity with respect to a given optical configuration on a flow cytometer.As shown in Table 1, displaying the mean SI 6 SEM of cells stained with different antibodies, seven out of nine of the lyophilized antibodies showed a higher SI compared to the liquid antibodies (for example: Foxp3 Alexa Fluor 488, liquid SI = 3.7, lyophilized SI = 5.1) The SI of cells stained with two lyophilized antibodies conjugated with tandem dyes (APC-H7 and PE-Cy5) was lower compared to the cells stained with liquid antibodies, suggesting that these tandem fluorochromes might be more sensitive to the lyophilisation procedure. Overall these results suggest that the antibody-fluorochrome combinations used for the cocktail in this study are stable and perform better in a lyophilized format.Lyoplate Flow Cytometry for Biomarker DiscoveryTable 1. Stain indexes (SI) of cells stained with lyophilized antibodies were higher than the liquid counterparts.Marker CD3 CD4 CD8 CD45RO CD25 Foxp3 IFN-c IL-17A IL-Fluorochrome APC-H7 APC BD Horizon V500 PE-Cy5 PE-Cy7 Alexa Fluor 488 Alexa Fluor 700 BD Horizon V450 PESI Liquid antibody (mean EM) 6.360.5 22.761.3 12.760.7 9.660.4 2.160.1 3.760.1 34.262.2 32.861.1 6.360.SI Lyophilized antibody (mean \llpEM) 5.860.4 26.961.31 15.560.9 7.360.8 2.360.1 5.160.2 35.662.8 38.463.6 8.060.p value ns *** *** * * *** ns ns nsStain index, calculated as D/W, where D = difference between the medians of the positive and negative populations and W = spread (26 rSD) of the negative population, is 23977191 indicated for each antibody-fluorochrome combination 6 SEM. The SI was calculated at one time point. Paired t test or Wilcoxon signed rank test was PD-168393 performed, *P,0.05, ***P,0.001. doi:10.1371/journal.pone.0065485.tConventional and lyoplate-based flow cytometry platforms have comparable intra- and inter-assay variabilityIn an eff.Uid or lyophilized antibodies. Frequencies of CD3+CD4+, CD3+CD8+, CD3+CD4+CD45RO+ (memory CD4+ T cells), CD3+CD8+CD45RO+ (memory CD8+ T cells) and Tregs (CD3+CD4+CD25highFoxP3+) cells were calculated using unstimulated samples, while frequencies of IFN-c+, IL-17A+, or IL-10+ cells were calculated from stimulated samples within memory CD4+ or memory CD8+ T cells. Cell frequencies obtained by LFP and CFP were compared using Bland Altman plots in which the differences between the cell frequencies obtained by the two methods (calculated as CFP minus LFP, y axis) are plotted against the cell frequency averages of the two methods (x axis). Horizontal lines are drawn at the mean difference (bias), and at the limits of agreement, which are defined as the mean difference 61.96 times the SD of the differences. The tables associated with each plot indicate cell frequency mean 6 SD measured by CFP and LFP, and the p value for a paired t test or Wilcoxon signed rank test, **P,0.01, ***P,0.001. B-E. IL-10+ (B,D) and IFN-c+(C,E) cells, within CD4+ and CD8+ memory T cells, are plotted after logarithmic transformation. doi:10.1371/journal.pone.0065485.gwith lyophilized reagents contribute to an increased detection of markers such as IFN-c and IL-10. Taken together these results suggest that LFP has higher sensitivity to detect key cytokines.Lyophilized antibodies result in higher stain index in stained cells compared to liquid antibodiesNext, we qualitatively compared the performance of liquid and lyophilized antibodies by calculating the stain index (SI) of stained cells, which is a measure of the brightness of a marker and its resolution sensitivity with respect to a given optical configuration on a flow cytometer.As shown in Table 1, displaying the mean SI 6 SEM of cells stained with different antibodies, seven out of nine of the lyophilized antibodies showed a higher SI compared to the liquid antibodies (for example: Foxp3 Alexa Fluor 488, liquid SI = 3.7, lyophilized SI = 5.1) The SI of cells stained with two lyophilized antibodies conjugated with tandem dyes (APC-H7 and PE-Cy5) was lower compared to the cells stained with liquid antibodies, suggesting that these tandem fluorochromes might be more sensitive to the lyophilisation procedure. Overall these results suggest that the antibody-fluorochrome combinations used for the cocktail in this study are stable and perform better in a lyophilized format.Lyoplate Flow Cytometry for Biomarker DiscoveryTable 1. Stain indexes (SI) of cells stained with lyophilized antibodies were higher than the liquid counterparts.Marker CD3 CD4 CD8 CD45RO CD25 Foxp3 IFN-c IL-17A IL-Fluorochrome APC-H7 APC BD Horizon V500 PE-Cy5 PE-Cy7 Alexa Fluor 488 Alexa Fluor 700 BD Horizon V450 PESI Liquid antibody (mean EM) 6.360.5 22.761.3 12.760.7 9.660.4 2.160.1 3.760.1 34.262.2 32.861.1 6.360.SI Lyophilized antibody (mean \llpEM) 5.860.4 26.961.31 15.560.9 7.360.8 2.360.1 5.160.2 35.662.8 38.463.6 8.060.p value ns *** *** * * *** ns ns nsStain index, calculated as D/W, where D = difference between the medians of the positive and negative populations and W = spread (26 rSD) of the negative population, is 23977191 indicated for each antibody-fluorochrome combination 6 SEM. The SI was calculated at one time point. Paired t test or Wilcoxon signed rank test was performed, *P,0.05, ***P,0.001. doi:10.1371/journal.pone.0065485.tConventional and lyoplate-based flow cytometry platforms have comparable intra- and inter-assay variabilityIn an eff.