Immunomagnetic Purging of Marrow and Peripheral Blood Progenitors for Autografting in Patients with Lymphoproliferative Disorders — Selection Efficacy and Engraftment

Abstract

For the diminution of tumor cell contamination in the grafts of patients with acute lymphoblastic leukemia (ALL — 6), multiple myeloma (MM — 6) and non-Hodgkin’s lymphomas (NHL — 3), a negative immunomagnetic selection was applied. Hematopoietic cells were collected from bone marrow (2) and blood (13), after mobilization with cyclophosphamide and G-CSF. Negative selection was performed using an indirect immunomagnetic method by incubation of cells with monoclonal antibodies and subsequently with anti-IgG coated Dynabeads. The following antibodies were used: in T cell ALL — anti CD2, CD3, CD5, CD7, in B cell ALL — anti CD10, CD19, CD20, CD22, in MM — CD10, CD19, CD20, CD22, CD37 and in NHL — anti CD19, CD20, CD22, CD23, CD37. Selection efficacy was as follows: in ALL-T type: 98.0 — 99.9%, in ALL-B type: 97.1 – 99.7%, in MM: 99.5 – 99.9% and in NHL: 97.1 – 100%. The high efficacy of negative selection was connected, however, with the loss of hematopoietic cells and the multipotential/committed progenitors. The recovery of CD34⁺ cells was 74.2% (58.8–85.0%) and for the following progenitors: CFU-blast, CFU-mix, BFU-E, CFU-E, CFU-GM(i4) and CFU-GM(7) in the range from 72.0 to 76.1%. Before transplantation patients received high-dose therapy: in ALL — BuCy-2 + etoposide, in MM — melphalan, and in NHL — dexa-BEAM. Fourteen patients had a complete hematopoietic recovery. The number of granulocytes > 0.5 and >1.0 G/1 was reached after a median of 13 (10 – 24) and 18 (11 – 28) days, respectively. Platelet recovery >20 and >50 G/1 was observed after 21 (11 – 28) and 28 (12 – 45) days, respectively. One patient with T-ALL died at day +23 because of septic shock without any sign of engraftment. We conclude that negative immunomagnetic selection of autografts effectively reduces tumor contamination and does not affect significantly the speed of engraftment in patients with lymphoproliferative disorders.