The simultaneous isolation of multiple high and low frequent T-cell populations from donor peripheral blood mononuclear cells using the major histocompatibility complex I-Streptamer isolation technology

Background. Adoptive transfer of donor-derived T cells can be applied to improve immune reconstitution in immunecompromised patients after allogeneic stem cell transplantation. The separation of beneficialT cells from potentially harmful T cells can be achieved by using the major histocompatibility complex (MHC) I-Streptamer isolation technology, which has proven its feasibility for the fast and pure isolation of T-cell populations with a single specificity. We have analyzed the feasibility of the simultaneous isolation of multiple antigen-specific T-cell populations in one procedure by combining different MHC I-Streptamers. Methods. First, the effect of combining different amounts of MHC I-Streptamers used in the isolation procedure on the isolation efficacy of target antigen-specific T cells and on the number of off-target co-isolated contaminating cells was assessed. The feasibility of this approach was demonstrated in large-scale validation procedures targeting both high and low frequentT-cell populations using the Good Manufacturing Practice (GMP)-compliant CliniMACS Plus device. Results. T-cell products targeting up to 24 different T-cell populations could be isolated in one, simultaneous MHC I-Streptamer procedure, by adjusting the amount of MHC I-Streptamers per target antigen-specific T-cell population. Concurrently, the co-isolation of potentially harmful contaminating T cells remained below our safety limit. This technology allows the reproducible isolation of high and low frequent T-cell populations. However, the expected therapeutic relevance of direct clinical application without in vitro expansion of these low frequent T-cell populations is questionable. Discussion. This study provides a feasible, fast and safe method for the generation of highly personalized MHC I-Streptamer isolated T-cell products for adoptive immunotherapy.