The majority of T lymphocytes are polyclonal during the chronic phase of chronic myelogenous leukemia

Clonal analysis of granulocyte-monocyte colony-forming unit cells with the human androgen receptor gene in chronic myeloid leukemia

Coexistence of Philadelphia chromosome-negative (Ph-) progenitors with the Ph+ clone in the early chronic phase of chronic myeloid leukemia (CML) has been documented in previous reports. A different evaluation of methods is needed to justify the clonality of the residual Ph- progenitors. Therefore, the X chromosome inactivation patterns in individual granulocyte-monocyte colony-forming unit (CFU-GM) colonies were studied with the clonality assay for the human androgen receptor gene. A prerequisite for this evaluation was the validation of T-lymphocytes and buccal cells as control cells representing the constitutional lyonization. The percentages of polyclonal CFU-GM cells were determined in 9 Ph+ women with CML and in 5 healthy women. Results of the clonal analysis of CFU-GM colonies were compared with those from reverse transcriptase-polymerase chain reaction analysis of single colonies for BCR/ABL transcripts. Both methods of CFU-GM cell analysis were in agreement regarding the presence of variable proportions (0%-94%) of normal cells in CML. Our results suggest that (a) T-cells and buccal cells have potential for use as controls for the clonal analysis of CML cases and (b) this method can evaluate the frequency of polyclonal/clonal CFU-GM cells in CML cases and is applicable to the analysis of myeloid clonal disorders that lack specific molecular markers.

Efficiency of interphase fluorescence in situ hybridization for BCR/ABL on peripheral blood smears for monitoring of CML patients: a comparison with bone marrow findings

Conventional cytogenetic analysis (CCA) is the standard method for monitoring of the Philadelphia (Ph) chromosome in chronic myeloid leukemia (CML). Evaluation of breakpoint cluster region/abelson murine leukemia (BCR/ABL) fusion using interphase fluorescence in situ hybridization on peripheral blood smears (PB-FISH) might be another approach allowing more frequent and less invasive follow-up investigations. Herein, BCR/ABL fusion gene was assessed on 21 PB smears from 16 CML patients in chronic phase. Results of PB-FISH were compared with those of CCA and interphase FISH on bone marrow aspirates (BM-FISH). PB-FISH analysis was combined with CD3 immunophenotyping that allowed simultaneous investigation of the leukemic status of CD3(+) T lymphocytes and scoring CD3(-) cells for BCR/ABL fusion gene. Moreover, the frequency of BCR/ABL fusion in nonlymphoid PB cells was estimated according to the differential leukocyte counts. The incidence of BCR/ABL(+) fusion signals in CD3(+) T cells of CML patients was 5.3% (SD +/- 1.9) and did not exceed the normal cut-off value of 8%. A significant correlation (P < 0.001) was found between results of PB-FISH and methods of BM analysis (CCA or BM-FISH). Correction of PB-FISH results to include only nonlymphoid or CD3(-) cells reduced the mean of differences and improved agreement between PB-FISH and CCA or BM-FISH methods. The best agreement was noted between CCA and PB-FISH on nonlymphoid cells. On the other hand, results of BM-FISH agreed well with those of PB-FISH on CD3(-) cells. These findings imply that PB-FISH on nonlymphoid or CD3(-) cells is reliable and may replace BM analysis for monitoring of response to treatment in CML patients.

The naive T-lymphocyte compartment is well preserved in patients with chronic myelogenous leukaemia in chronic phase

In chronic myelogenous leukaemia (CML), clonal change occurs in all myeloid and B-cell lineages, but very rarely T-cell lineages. A detailed three-colour cytometric analysis of peripheral lymphocytes was performed in 22 patients with chronic-phase CML (CP-CML). CD45 gating analysis was used to discriminate between lymphocytes and basophils. The peripheral lymphocyte pool was comprised of a significant proportion of naive CD4 cells, defined by a CD4+45RA+ phenotype [47.0 +/- 19.6% (mean +/- SD) of the total CD4+ cells], and naive CD8 cells, defined by a CD8+CD45RA+CD28+ phenotype (35.1 +/- 19.7% of total CD8+ cells), even in patients with long disease duration. The percentage of CD8 naive T cells showed inverse correlation with age, whereas no correlation was observed with disease duration. Possible explanations for the preservation of naive lymphocytes include (1) that the naive T cells differentiated from co-existing normal stem cells or (2) that long-lived naive T cells persisted from the CML onset and expanded peripherally (thymus independent). Either mechanism or a combination of both mechanisms might contribute to maintaining the naive compartment size.

Analysis of the distribution of CAG repeats and X-chromosome inactivation status of HUMARA gene in healthy female subjects using improved fluorescence-based assay

We investigated the polymorphic CAG-repeat distribution and the X-inactivation status of the human androgen receptor (HUMARA) gene in 58 female Japanese volunteers. Polymerase chain reaction amplification was performed using a fluorescent-dye-labeled primer under conditions specific for GC-rich targets, and fragments were analyzed. To estimate the length of these fragments, FAM-labeled (blue fluorescent) products were simultaneously compared with ROM-labeled size markers (red) that were created by sequencing various HUMARA fragments. The number of polymorphic CAG repeats of HUMARA in 116 alleles from 58 female subjects ranged from 15 to 28. Of the 58 volunteers, 51 (88.0%) were heterozygous. In 96% of the heterozygous female subjects, the allelic differences were no greater than 6 repeats. X-chromosome inactivation was calculated as the ratio of the area of the smaller peak to the sum of the areas of the smaller and larger peaks. The average ratio was 0.38 (range, 0.09-0.50). Preferential use of 1 allele, by more than 75% (ratio. <0.25). was observed in 5 volunteers (10.9%). The clonal nature of a patient with chronic myelogenous leukemia was easily identified. This method is sensitive enough to discriminate a difference of 1 triplet repeat.

Therapy-related changes of CD20+ and CD45RO+ lymphocyte subsets in chronic myeloid leukemia (CML): an immunohistochemical and morphometric study on sequential trephine biopsies of the bone marrow

Little information exists about the amount of CD45RO+-T- and CD20+-B-lymphocytes in the bone marrow of patients with Philadelphia chromosome-positive chronic myelogenous leukemia (Ph1+-CML) at presentation or regarding corresponding changes during therapy. On the other hand, quantification of this cell compartment seems to be imperative for two reasons: first, the presumed association of immunocompetent lymphocyte subsets in the expansion of the leukemic cell clone; and second, a speculated relationship with the complex generation of myelofibrosis. Therefore, an immunohistological and morphometric study was performed on 219 representative trephine biopsies of the bone marrow derived from 70 patients with repeated examinations during the course of Ph1+-CML. For the identification of the different lymphocyte populations, the monoclonal antibodies UCHL-1 (CD45RO) and L26 (CD20) were applied on formaldehyde-fixed and decalcified specimens. In comparison to a control group and calculated per hematopoietic cells, the CML bone marrow showed about a 50% decrease in the total amount of lymphocytes. Determination of CD45RO+ and CD20+ subsets revealed a significant enhancement during treatment. Because of the different intervals (range, 10 to 25 mo) between first and last biopsy in the various therapeutic groups, results had to be modified by considering dynamic features. This calculation included changes of the lymphocyte subpopulations related to time. Contrasting the CD45RO+ lymphocytes, a relevant increase in the CD20+ subset could be observed after interferon-a treatment or corresponding combination regimens. No significant correlations were found between fiber density at onset (first biopsy) or development of fibrosis and lymphocyte proliferations in the course of CML. Our results are in keeping with the finding that a proper immune response consistent with an increased lymphocyte growth seems to be associated with a regression of the clonally-transformed cell population. Opposed to a repeatedly discussed pathomechanism, we failed to demonstrate any quantitative relationships between the extent of lymphocyte proliferations and occurrence or progression of myelofibrosis.

BCR/ABL− CD34+HLA-DR−Progenitor Cells in Early Chronic Phase, But Not in More Advanced Phases, of Chronic Myelogenous Leukemia Are Polyclonal

Chronic myelogenous leukemia (CML) is characterized by the Philadelphia (Ph) translocation and BCR/ABL gene rearrangement which occur in a pluripotent hematopoietic progenitor cell. Ph-negative (Ph−) hematopoiesis can be restored in vivo after treatment with -interferon or intensive chemotherapy, suggesting that normal stem and progenitor cells coexist with the Ph+ clone. We have previously shown that Ph− progenitors are highly enriched in the CD34+HLA-DR− fraction from early chronic phase (ECP) CML patients. Previous studies have suggested that the Ph-translocation represents a secondary clonal hit occurring in an already clonally mutated Ph− progenitor or stem cells, leaving the unanswered question whether Ph−CD34+HLA-DR- progenitors are normal. To show the clonal nature of Ph−CD34+HLA-DR− CML progenitors, we have compared the expression of BCR/ABL mRNA with X-chromosome inactivation patterns (HUMARA) in mononuclear cells and in CD34+HLA-DR+ and CD34+HLA-DR− progenitors in marrow and blood obtained from 11 female CML patients (8 in chronic phase and 3 in accelerated phase [AP] disease). Steady-state marrow-derived BCR/ABL mRNA−, CD34+HLA-DR−progenitors had polyclonal X-chromosome inactivation patterns in 2 of 2 patients. The same polyclonal pattern was found in the progeny of CD34+HLA-DR− derived long-term culture-initiating cells. Mobilization with intensive chemotherapy induced a Ph−, BCR/ABL mRNA−and polyclonal state in the CD34+HLA-DR−and CD34+HLA-DR+ progenitors from 2 ECP patients. In a third ECP patient, polyclonal CD34+ cells could only be found in the first peripheral blood collection. In contrast to ECP CML, steady-state marrow progenitors in late chronic phase and AP disease were mostly Ph+, BCR/ABL mRNA+, and clonal. Further, in the majority of these patients, a Ph−, polyclonal state could not be restored despite mobilization with intensive chemotherapy. We conclude from these studies that CD34+HLA-DR− cells that are Ph− and BCR/ABL mRNA− are polyclonal and therefore benign. This population is suitable for autografting in CML.

BCR/ABL− CD34+HLA-DR−Progenitor Cells in Early Chronic Phase, But Not in More Advanced Phases, of Chronic Myelogenous Leukemia Are Polyclonal

Chronic myelogenous leukemia (CML) is characterized by the Philadelphia (Ph) translocation and BCR/ABL gene rearrangement which occur in a pluripotent hematopoietic progenitor cell. Ph-negative (Ph−) hematopoiesis can be restored in vivo after treatment with -interferon or intensive chemotherapy, suggesting that normal stem and progenitor cells coexist with the Ph+ clone. We have previously shown that Ph− progenitors are highly enriched in the CD34+HLA-DR− fraction from early chronic phase (ECP) CML patients. Previous studies have suggested that the Ph-translocation represents a secondary clonal hit occurring in an already clonally mutated Ph− progenitor or stem cells, leaving the unanswered question whether Ph−CD34+HLA-DR- progenitors are normal. To show the clonal nature of Ph−CD34+HLA-DR− CML progenitors, we have compared the expression of BCR/ABL mRNA with X-chromosome inactivation patterns (HUMARA) in mononuclear cells and in CD34+HLA-DR+ and CD34+HLA-DR− progenitors in marrow and blood obtained from 11 female CML patients (8 in chronic phase and 3 in accelerated phase [AP] disease). Steady-state marrow-derived BCR/ABL mRNA−, CD34+HLA-DR−progenitors had polyclonal X-chromosome inactivation patterns in 2 of 2 patients. The same polyclonal pattern was found in the progeny of CD34+HLA-DR− derived long-term culture-initiating cells. Mobilization with intensive chemotherapy induced a Ph−, BCR/ABL mRNA−and polyclonal state in the CD34+HLA-DR−and CD34+HLA-DR+ progenitors from 2 ECP patients. In a third ECP patient, polyclonal CD34+ cells could only be found in the first peripheral blood collection. In contrast to ECP CML, steady-state marrow progenitors in late chronic phase and AP disease were mostly Ph+, BCR/ABL mRNA+, and clonal. Further, in the majority of these patients, a Ph−, polyclonal state could not be restored despite mobilization with intensive chemotherapy. We conclude from these studies that CD34+HLA-DR− cells that are Ph− and BCR/ABL mRNA− are polyclonal and therefore benign. This population is suitable for autografting in CML.

Specific depletion of alloreactive T cells in HLA-identical siblings: a method for separating graft-versus-host and graft-versus-leukaemia reactions

Accumulating evidence indicates that alloreactive donor T cells confer both graft-versus-host (GVH) and graft-versus-leukaemia (GVL) reactivity following allogeneic bone marrow transplantation. We have developed a method to deplete alloreactive donor T cells with an immunotoxin targeting the alpha chain of the IL-2 receptor. In patients with chronic myeloid leukaemia and their HLA-identical sibling donors, we measured donor helper T-lymphocyte precursor frequencies (HTLPf) against recipient peripheral blood mononuclear cells (PBMNC; donor versus host), recipient leukaemia cells (donor versus leukaemia) and third-party PBMNC, before and after the depletion. In seven pairs there was a 4.3-fold reduction of donor-versus-host HTLPf (P=0.017), without a significant change in the donor frequencies against third party (P=0.96). In eight further donor-recipient pairs, immunotoxin-depleted donor versus patient PBMNC HTLPf 4.5-fold (mean 1/155,000 before and 1/839,000 after depletion, P=0.007). There was a smaller non-significant 1.8-fold reduction in donor-versus-leukaemia HTLPf from 1/192,000 to 1/334,000 (P=0.19). These results suggest that selective T-cell depletion can significantly deplete donor anti-host reactivity while conserving anti-leukaemia reactivity in HLA-matched donor-recipient pairs.