Rapid and effective CD3 T-cell depletion with a magnetic cell sorting program to produce peripheral blood progenitor cell products for haploidentical transplantation in children and adults.
BACKGROUND
Effective T-cell depletion is a prerequisite for haploidentical peripheral blood progenitor cell (PBPC) transplantation. This study was performed to investigate the performance of magnetic cell sorting-based direct large-scale T-cell depletion, which is an attractive alternative to standard PBPC enrichment procedures.


METHODS
PBPCs were harvested from 11 human leukocyte antigen (HLA)-haploidentical donors. T cells labeled with anti-CD3-coated beads were depleted with a commercially available magnetic separation unit (CliniMACS, Miltenyi Biotec) with either the Depletion 2.1 (D2.1, n=11) or the novel Depletion 3.1 (D3.1, n=12) program. If indicated, additional CD34+ selections were performed (n=6). Eleven patients received T-cell-depleted grafts after reduced-intensity conditioning.


RESULTS
The median log T-cell depletion was better with the D2.1 compared to the D3.1 (log 3.6 vs. log 2.3, p<0.05) and was further improved by introducing an immunoglobulin G (IgG)-blocking step (log 4.5 and log 3.4, respectively). The D3.1 was superior to the D2.1 (p<0.05) in median recovery of CD34+ cells (90% vs. 78%) and in median recovery of CD3- cells (87% vs. 76%). The median processing times per 10(10) total cells were 0.90 hours (D2.1) and 0.35 hours (D3.1). The transplanted grafts (directly T-cell-depleted products with or without positively selected CD34+ cells) contained a median of 10.5 x 10(6) per kg CD34+, 0.93x10(5) per kg CD3+, and 11.6x10(6) per kg CD56+. Rapid engraftment was achieved in 10 patients. The incidences of acute graft-versus-host disease were less than 10 percent (Grade I/II) and 0 percent (Grade III/IV).


CONCLUSIONS
The novel D3.1 program with IgG blocking enables highly effective, time-saving large-scale T-cell depletion. Combining direct depletion techniques with standard CD34+ selection enables the composition of grafts optimized to the specific requirements of the patients.
Dykes
Josefina H
JH
Blood Center, the Department of Pediatric Oncology, Lund University Hospital, Lund, Sweden. josefina.dykes@med.lu.se
Toporski
Jacek
J
Juliusson
Gunnar
G
Békássy
Albert N
AN
Lenhoff
Stig
S
Lindmark
Anders
A
Scheding
Stefan
S
D000293:Adolescent; D000328:Adult; D018952:Antigens, CD34; D017252:CD3 Complex; D002648:Child; D002675:Child, Preschool; D006239:Haplotypes; D006412:Hematopoietic Stem Cells; D006650:Histocompatibility Testing; D006801:Humans; D018189:Immunomagnetic Separation; D016130:Immunophenotyping; D008212:Lymphocyte Depletion / Q000379:methods*; D008875:Middle Aged; D036102:Peripheral Blood Stem Cell Transplantation / Q000379:methods*; D014184:Transplantation, Homologous; D016896:Treatment Outcome
D018952:Antigens, CD34; D017252:CD3 Complex