Analysis of T cells and myeloid cells from patients before and after KTx and HCT. Representative 2-color staining of PBMCs before (A) and 9 weeks after (B) transplantation from a single patient. CD19⁺ B and CD56⁺ natural killer NK cells were gated out before identifying CD3⁺ T and CD11b⁺ myeloid cells (left panels). Lineage negative (Lin⁻ = CD3⁻CD19⁻CD56⁻) CD11b^hi myeloid cells are enclosed in boxes to identify phenotypic MDSCs (CD11b^hiDR^lo) and monocytes (CD11b^hiDR^hi) (middle panels). Further analysis of the phenotypic MDSCs for expression of CD14 monocytic vs CD15 granulocytic/pmn markers are shown (right panels). The percentage of cells in each box is indicated. Mean percentage (C) and absolute numbers (D) of T cells. Mean percentage (E) and absolute numbers (F) of total MDSCs pre vs posttransplant. HLA-matched recipients are represented as circles, HLA-mismatched recipients are represented as squares. Filled symbols indicate that the recipients were mixed chimeric (>5% donor type cells in whole blood), and open symbols indicate that the recipients were not chimeric at the time that the assay was performed. Data are mean ± standard error of the mean for each group. *P < .05, **P < .01, ***P < .001, Mann-Whitney U test of independent means; significance was subsequently determined by 1-way ANOVA, multicomparison analysis with Holm-Sidak correction. ns, not significant (P > .05).