A large-scale method for the selective depletion of alphabeta T lymphocytes from PBSC for allogeneic transplantation

We sought to develop a method for the clinical large-scale depletion of alphabeta T lymphocytes from mobilized peripheral stem cells, which would allow the allogeneic transplantation of a graft enriched for stem cells, natural killer (NK) cells and gammadelta T lymphocytes.

Therefore, we obtained mononuclear cells from either mobilized or non-mobilized healthy adult volunteer donors and incubated the cells with a biotinylated anti-alphabeta T-cell Ab and subsequently with an anti-biotin Ab conjugated with magnetic microbeads. The depletion was then performed using a CliniMACS device.

The median T-cell depletion was 3.9 log (range 3.5-4.1 log). The recovery of the gammadelta and NK cells was 92% and 80%, respectively. The recovery of CD34+ stem cells from the mobilized donors was 66%.

This method had no negative influence on the in vitro colony formation of stem cells, and transplantation of alphabeta-depleted cells into NOD-SCID IL-2 common gamma chain knockout (NOD-scid IL2r (null)) mice resulted in a rapid engraftment of human myeloid and lymphoid cells. This method will allow large-scale depletion of alphabeta T cells from mobilized peripheral blood in clinical trials.