Small number of HTLV-1-positive cells frequently remains during complete remission after allogeneic hematopoietic stem cell transplantation that are heterogeneous in origin among cases with adult T-cell leukemia/lymphoma.
Allogeneic hematopoietic stem cell transplantation (allo-HSCT) can provide long-term remission for patients with adult T-cell leukemia/lymphoma (ATLL) caused by human retrovirus, human T-lymphocyte virus (HTLV-1). To understand how HTLV-1-positive cells including ATLL cells were suppressed by allo-HSCT, we examined HTLV-1 provirus load and residual ATLL cells in peripheral blood of transplant recipients using PCR-based tests. We found that the copy number of HTLV-1 genome, called provirus, became very small in number after allo-HSCT; however, in most cases, provirus did not disappear even among long-term survivors. Tumor-specific PCR tests demonstrated that most of HTLV-1-positive cells that remained long after transplantation were not primary ATLL cells but donor-derived HTLV-1-positive cells. We also found a case having very low amount of residual disease in peripheral blood even long after transplantation. There was only one recipient in whom we failed to show the presence of HTLV-1 genome and antibody against HTLV-1 even with an extensive search, which strongly suggested the elimination of HTLV-1 after allo-HSCT. These results demonstrated that after allo-HSCT the small amount of residual HTLV-1-positive cells were heterogeneous in origin and that long-term disease control for ATLL could be obtained without the complete elimination of HTLV-1.
Yamasaki
R
R
Molecular Medicine Unit and Hematology, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Miyazaki
Y
Y
Moriuchi
Y
Y
Tsutsumi
C
C
Fukushima
T
T
Yoshida
S
S
Taguchi
J
J
Inoue
Y
Y
Matsuo
E
E
Imaizumi
Y
Y
Imanishi
D
D
Fujimoto
T
T
Tsushima
H
H
Honda
S
S
Hata
T
T
Tsukasaki
K
K
Tomonaga
M
M
D000328:Adult; D018380:Hematopoietic Stem Cell Transplantation; D015368:Human T-lymphotropic virus 1 / Q000302:isolation & purification*; D006801:Humans; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000473:pathology / Q000628:therapy*; D016133:Polymerase Chain Reaction; D012074:Remission Induction; D014019:Tissue Donors; D014184:Transplantation, Homologous; D019562:Viral Load