Effect of cryopreservation on PBMC cytokine responses. Data points represent cytokine responses by the same subjects' PBMC either cultured fresh or after cryopreservation. A, C. cells were stimulated for Each data point represents the comparison of the same subject at the same time point. Data shown include up to 3 time points per subject. The dotted line represents perfect agreement or concordance, and the solid line is best fit to data. Rho = Pearson correlation; CCC = Concordance Correlation Coefficient. See methods for details of statistical analysis. * p < 0.05; ** p < 0.01; ***p < 0.001.