Effect of cryopreservation on CBMC cytokine responses. Data points represent cytokine responses by the same subjects' CBMC either cultured fresh or after cryopreservation. 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.