Immune landscape and donor chimerism from diagnosis through alloHSCT. (A) Monitoring of donor chimerism and enumeration of the patient’s CD3⁺ T cells, CD4⁺ T cells, CD8⁺ T cells, CD19⁺ B cells, and NK cells during the course of observation. The dotted gray lines define the upper and lower ends of the reference intervals, which were established during the validation of these clinical assays at Mayo Clinic. (B) Longitudinal monitoring of the patient’s CD40L expression and binding in comparison to the donor (left panel), with representative examples of the flow plots displayed in the middle (CD40L expression) and right (CD40 binding) panels. (C) Longitudinal enumeration of the absolute number of CD27+IgM-IgD class-switched memory B cells (left panel), with flow plots displaying their gradual increase as a proportion (%) of CD27⁺ memory B cells over time (subsequent panels). (D) Evaluating thymic output by quantifying CD4 recent thymic emigrants and T cell receptor excision circles. Values above the dotted gray line in the TREC plot are within the normal reference interval. (E) Evaluation of the patient’s TCRVβ repertoire. (F) Longitudinal assessment of the T cell proliferative response to PHA, anti-CD3, anti-CD3 + anti-CD28, and anti-CD3 + IL2. PHA, phytohemagglutinin.