ALC (μL−1) recovery after ATG+TBI and SCT. (A) Two periods of growth are seen, first from days 0 to 30 when patients are on MMF (blue outline) and the second from day 20 to approximately day 120 (orange outline). Each period demonstrates an initial phase of slow growth, followed by exponential expansion and finally relatively stable counts, until tacrolimus is discontinued, when greater variability is observed. Data from a matched related donor (MRD) and an unrelated donor (URD) SCT are shown. (B) Logistic dynamics of lymphoid recovery after SCT. Three patterns are observed corresponding to high, pattern A; intermediate, pattern B; and slow growth rate, pattern C.