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CD34 selections from myeloma peripheral blood cell autografts contain residual tumour cells due to impurity, not to CD34 + myeloma cells
Author(s) -
Willems P.,
Croockewit A.,
Raymakers R.,
Holdrinet R.,
Van Der Bosch G.,
Huys E.,
Mensink E.
Publication year - 1996
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1046/j.1365-2141.1996.d01-1677.x
Subject(s) - cd34 , progenitor cell , flow cytometry , cell sorting , bone marrow , minimal residual disease , multiple myeloma , microbiology and biotechnology , stem cell , biology , haematopoiesis , pathology , cancer research , immunology , medicine
Malignant cells in haemopoietic autografts can contribute to post‐transplant relapse. Engraftment of myeloma patients with CD34 + peripheral blood progenitors selected from total autografts reduces the number of tumour cells infused by 2.7–4.5 logs. Residual tumour cells detected in CD34 + selected cells may be due to selection impurity or the existence of malignant CD34 + progenitors. In three patients we evaluated the CD34 purity and tumour load of total autografts, CD34 + progenitors selected with immunomagnetic beads and highly purified CD34 + progenitors obtained in two rounds of selection (combining magnetic with flow cytometry activated cell sorting) to determine the cause of residual tumour cells in CD34 selections. Using allele‐specific oligonucleotides (ASO) complementary to the unique Ig heavy chain sequence (CDRIII region) of the malignant clone, semi‐quantitative ASO‐PCR was capable of detecting one malignant cell in 10 4 –10 5 normal white blood cells. Selection of CD34 + cells from bone marrow (BM) with approximately 20% malignant plasma cells resulted in a 1.4 log reduction of tumour burden. Using two‐colour flow‐cytometry we observed CD34 − , BB4 + malignant plasma cells contaminating this CD34 selection. Prior to sorting, peripheral blood cell autografts (PBCA) contained approximately 0.1% malignant cells. Selection of >99% pure CD34 + cells using immunomagnetic beads (Dynal) resulted in an approximate 2 log reduction of malignant cells, but residual tumour cells were still detectable. ASO‐PCR detected no malignant cells in >99.9% pure CD34 + peripheral blood progenitors obtained with two rounds of selection (combining magnetic with flow cytometry activated cell sorting). We conclude that CD34 + malignant cells are not detectable in myeloma PBCA and that residual tumour cells in CD34 selections are due to contaminating CD34‐negative cells.