Comparison of the percentage of labeled (▵) and unlabeled lymphocytes (▴) in the blood following the intravenous injection of FITC⁺ blood lymphocytes. The number of samples per time point is indicated in parentheses. *, indicates a significant difference (P < .05) between the concentration of labeled and unlabeled cells at the same time point; ^†, indicates a significant difference between the concentration of FITC⁺ subsets in the original injected dose of labeled cells (the first ▵ on each graph) and in subsequent blood samples.