Immunosuppression is needed in HLA identical sibling renal transplantation. We conducted a tolerance trial in this patient cohort using Alemtuzumab induction, donor hematopoietic stem cells, tacrolimus/mycophenolate immunosuppression converted to sirolimus, planning complete drug withdrawal by 24 months post-transplantation. After an additional 12 months with no immunosuppression, normal biopsies and renal function, recipients were considered tolerant. Twenty recipients were enrolled. Of the first 10 (>36 months post-transplantation), 5 had immunosuppression successfully withdrawn for 16-36 months (tolerant), 2 had disease recurrence and 3 had subclinical rejection in protocol biopsies (non-tolerant). Microchimerism disappeared after 1 year, and CD4+CD25highCD127-FOXP3+ T cells and CD19+IgD/M+CD27- B cells increased to 5 years post-transplantation in both groups, whereas immune/inflammatory gene expression pathways in the peripheral blood and urine were differentially downregulated in tolerant compared to non-tolerant recipients. Therefore, in this HLA identical renal transplant tolerance trial, absent chimerism, Treg and Breg immunophenotypes were indistinguishable between tolerant and non-tolerant recipients, but global genomic changes indicating immunomodulation were observed only in tolerant recipients. A total of 46 PBMC samples representing blood draws from four time points in the first 9 recipients were processed for microarray analysis (The Scripps Research Institute, La Jolla, CA). The analyzed time points were: immediately pre-operatively in the absence of immunosuppression (n=9); post-operatively at 1 year (n=8, range 11-13 months); at 2 years (n=12, range 18-25 months); >3 years (n=17, range 32-48 months). (At year 2 and at > 3 years, repeated samples were obtained from individual subjects, and at one year, one subject had a technically unsatisfactory sample.) To discount the effects of immunosuppression on gene expression, microarray data were included on whole blood from 18 healthy human subjects (controls: GSE40586; NCBI Gene Expression Omnibus [GEO] repository).