Terminal deoxynucleotidyl transferase‐positive cells in trephine biopsies following bone marrow or peripheral stem cell transplantation reflect vigorous B‐cell generation

Abstract

Bone marrow of adult patients after BMT/SCT is capable of initiating vigorous precursor B-cell generation, which is not seen in untransplanted adults. However, the increase of immature B cells was variable in our study. Only in two young adult patients did it reach the magnitude of B-cell generation seen in infantile bone marrow where immunocompetent B cells are produced normally. A marked increase in number of immature B cells post-transplant may mimic B-cell acute lymphoblastic leukaemia (B-ALL). This is a potential problem in patients transplanted for B-ALL itself. Since reactive and neoplastic B-cell precursors share the same immunophenotype in paraffin-embedded tissue, additional tools, particularly molecular techniques, may have to be employed to establish the correct diagnosis.

Multi-color immune-phenotyping of CD34 subsets reveals unexpected differences between various stem cell sources

“…Woolthuis et al 38 reported a loss of quiescence and impaired function of CD34 + /CD38 low cells 1 year after autologous stem cell reinfusion. These reports are in line with our observation of a significant increase of CD133 dim MLP and CD133 − BLP in BM1y, which was also described by Wolf et al 39 BM biopsies 1 year after transplantation are usually only performed after allogeneic, but not after autologous transplantation. However, Bhatia et al 40 examined BM of Non-Hodgkin and Hodgkin lymphoma patients 0.5-3 years after autologous PBSC reinfusion.…”

Non-Neoplastic TdT-Positive Cells in Bone Marrow Trephines with Acute Myeloid Leukaemia before and after Treatment Express Myeloid Molecules

“…Another aspect of our study was to find out if the TdTpositive cells are increased or decreased after therapy: we expected an increase in TdT-positive non-neoplastic cells after treatment, because of the therapy-associated bone marrow depletion with the resulting need for regeneration [10] . Surprisingly, a decrease in these cells after therapy was detected at similar frequency as an increase.…”

“…Some authors have investigated TdT-positive cells in bone marrow biopsies from patients with acute leukaemia focussing on the separation of haematogones from tumour cells of ALL [11] . According to their results, TdT-positive cells were defined as haematogones (normal precursor B cells), which reflect the vigorous B cell generation after treatment [10] . Other authors described primitive lymphoid progenitors in bone marrows with a T lineage reconstruction potential [12] .…”

“…Haematogones are more abundant in children than in adults [8,9] . Con ditions of significant bone marrow suppression or B cell dysfunction in adults including multi-agent chemotherapy, bone marrow transplantation and infections are linked with increased haematogones [10] . Using an antibody panel including TdT in our daily diagnostic routine, we could observe that a proportion of patients with AML have increased TdT-positive non-neoplastic cells at time of diagnosis as well as after therapy often without an additional expression of CD20, CD10 or CD19.…”

Bone Marrow B cell Precursor Number after Allogeneic Stem Cell Transplantation and GVHD Development

“…Increased BM precursor B cell numbers have been found after HSCT [17], but examinations of BM aspirates in GVHD have been inconclusive [15]. Decreased frequency of B cell precursors in BM aspirates using flow cytometry before, during, and after development of acute GVHD (aGVHD) and cGVHD have been observed, but given the variability of sample cellularity and composition, these studies are difficult to interpret [15, 18, 19].…”