Human LAP(+)GARP(+)FOXP3(+) regulatory T cells attenuate xenogeneic graft versus host disease

Wang, Huihui; Song, Hyo; Pham, Anha V.; Cooper, Laurence J.; Schulze, Janika J.; Olek, Sven; Tran, Dat Q.

In the absence of a repurification process, the final expanded Treg product would have highly variable content of bona fide Tregs and contaminated, expanded nonTregs ( Figure 2D ). To address this issue, other protocols have implemented rapamycin which has improved the percentage of Tregs, but variability still exists [15, 36] . Consistent with other studies, some of our expanded CD25 + populations maintained >75% FOXP3 + and >60% TSDR demethylation ( Figure 5B ). These CD25 + populations did possess sufficient suppressive function similar to the repurified LAP + Tregs ( Figure 6A, C) . We were unable to demonstrate a statistical difference between CD25 + populations and LAP + Tregs due to the high variability in Treg percentage within some of the CD25 + populations. Therefore, it would be prudent to manufacture highly purified Treg immunotherapy, similar to the standard required for conventional drug manufacturing. Regardless of the variability in bona fide Tregs within the final product, implementing LAP repurification would normalize and produce a highly purified and more homogenous Treg product.