Correlation between alemtuzumab levels and CD3 chimerism post-HSCT. Alemtuzumab levels measured at 14 days after transplant were plotted against the CD3 chimerism (% donor) measured at 2, 4, 6, 12, and 24 months after transplant for each patient on a scatter plot. Regression lines are included in each panel. Statistically significant correlations were seen between alemtuzumab levels and chimerism drawn 2 months (R2 = 0.40, p = 0.004) and 4 months after the transplant (R2 = 0.36, p = 0.005)