Purification of human natural killer cells using a clinical-scale immunomagnetic method

Area of Science:

• Immunology
• Cell Therapy
• Transplantation Medicine

Background:

• Allogeneic bone marrow transplantation (BMT) is associated with significant adverse events including infection, graft failure, relapse, and graft-versus-host disease (GvHD).
• Donor leukocyte infusion can mitigate some risks but carries a high risk of T cell-mediated GvHD.
• Natural killer (NK) cells show promise in animal models for preventing or treating these adverse events, suggesting their potential clinical utility.

Purpose of the Study:

• To develop an automated, efficient, and clinical-scale method for purifying human NK cells.
• To assess the feasibility of using NK cells to mitigate adverse events in allogeneic BMT.

Main Methods:

• A two-step immunomagnetic purification process was employed on leukapheresis products.
• CD3+ T cells were depleted first, followed by enrichment of CD56+ NK cells.
• The method was designed for automated, large-scale clinical application.

Main Results:

• The purification method yielded a median of 91.0% pure NK cells with 48.7% recovery.
• Significant depletion of T cells (median 5.3 log) was achieved, minimizing contamination.
• Purified NK cells exhibited approximately five-fold higher natural cytotoxicity compared to unpurified cells, with further enhancement possible via IL-2 stimulation.

Conclusions:

• A scalable, automated method for efficient human NK cell isolation with minimal T and B cell contamination has been established.
• The purified NK cells demonstrate enhanced cytotoxic activity.
• These findings support the potential application of these purified NK cells in preclinical and clinical settings for improving BMT outcomes.