Generation of alloreactivity-reduced donor lymphocyte products retaining memory function by fully automatic depletion of CD45RA-positive cells.

BACKGROUND AIMS

For patients needing allogeneic stem cell transplantation but lacking a major histocompatibility complex (MHC)-matched donor, haplo-identical (family) donors may be an alternative. Stringent T-cell depletion required in these cases to avoid lethal graft-versus-host disease (GVHD) can delay immune reconstitution, thus impairing defense against virus reactivation and attenuating graft-versus-leukemia (GVL) activity. Several groups reported that GVHD is caused by cells residing within the naive (CD45RA) T-cell compartment and proposed use of CD45RA-depleted donor lymphocyte infusion (DLI) to accelerate immune reconstitution. We developed and tested the performance of a CD45RA depletion module for the automatic cell-processing device CliniMACS Prodigy and investigated quality attributes of the generated products.

METHODS

Unstimulated apheresis products from random volunteer donors were depleted of CD45RA cells on CliniMACS Prodigy, using Good Manufacturing Practice (GMP)-compliant reagents and methods throughout. Using phenotypic and functional in vitro assays, we assessed the cellular constitution of CD45RA-depleted products, including T-cell subset analyses, immunological memory function and allo-reactivity.

RESULTS

Selections were technically uneventful and proceeded automatically with minimal hands-on time beyond tubing set installation. Products were near-qualitatively CD45RA depleted, that is, largely devoid of CD45RA T cells but also of almost all B and natural killer cells. Naive and effector as well as γ/δ T cells were greatly reduced. The CD4:CD8 ratio was fivefold increased. Mixed lymphocyte reaction assays of the product against third-party leukocytes revealed reduced allo-reactivity compared to starting material. Anti-pathogen responses were retained.

DISCUSSION

The novel, closed, fully GMP-compatible process on Prodigy generates highly CD45RA-depleted cellular products predicted to be clinically meaningfully depleted of GvH reactivity.