In this study, we compared the genomic integration efficiencies and 
transposition site preferences of Sleeping Beauty (SB or SB11), Tol2, and 
piggyBac (PB) transposon systems in primary T cells derived from peripheral 
blood lymphocytes (PBL) and umbilical cord blood (UCB). We found that PB 
demonstrated the highest efficiency of stable gene transfer in PBL-derived T 
cells, whereas SB11 and Tol2 mediated intermediate and lowest efficiencies, 
respectively. Southern hybridization analysis demonstrated that PB generated the 
highest number of integrants when compared to SB and Tol2 in both PBL and UCB T 
cells. Tol2 and PB appeared more likely to promote clonal expansion than SB, 
which may be in part due to the dysregulated expression of cancer-related genes 
near the insertion sites. Genome-wide integration analysis demonstrated that SB, 
Tol2, and PB integrations occurred in all the chromosomes without preference. 
Additionally, Tol2 and PB integration sites were mainly localized near 
transcriptional start sites (TSSs), CpG islands and DNaseI hypersensitive sites, 
whereas SB integrations were randomly distributed. These results suggest that SB 
may be a preferential choice of the delivery vector in T cells due to its random 
integration site preference and relatively high efficiency, and support 
continuing development of SB-mediated T-cell phase I trials.