Phenotypic subtypes of leukaemic transformation in chronic myelomonocytic leukaemia

Chronic myelomonocytic leukaemia (CMML) is a haematological disorder with high risk of transformation to acute myeloid leukaemia (AML). To characterize the phenotypic and genomic patterns of CMML progression, we evaluated a cohort of 189 patients with AML evolving from CMML. We found that transformation occurs through distinct trajectories characterized by genomic profiles and clonal evolution: monocytic (Mo-AML, 53%), immature myeloid (My-AML, 43%) or erythroid (Ery-AML, 2%). Mo-AML, characterized by expansion of monoblasts and promonocytes (low CD34, CD117 expression; high CD14, CD33, CD56 and CD64 expression), were defined by SRSF2, TET2 and RAS pathway mutation co-dominance and were more likely to evolve from SRSF2-TET2 co-mutant CMML through emergence/expansion of RAS pathway mutant clones. Conversely, My-AML, characterized by expansion of immature myeloid blasts (high frequency of CD34, CD38, CD117; low frequency of CD14, CD64 and CD56 expression) were less likely to exhibit SRSF2-TET2 co-mutations or RAS pathway mutations and had higher frequency of CEBPA mutations. Ery-AML was defined by complex karyotypes and TP53 mutations. A trend towards improved OS and EFS with hypomethylating agent-venetoclax combination was observed in My-AML, but not Mo-AML. These findings define distinct progression of CMML and set the basis for future studies evaluating the role of phenotype-specific therapeutics.     

Dendritic cells in chronic myelomonocytic leukaemia

Blood dendritic cells (DC) differentiate in vitro via two separate pathways: either directly from blood DC precursors (DCp) or from CD14+ monocytes. In chronic myelomonocytic leukaemia (CMML) abnormal bone marrow precursors contribute to blood monocyte development but DC development has not been studied previously. Monocytes comprised 60% of blood MNC in 15 CMML patients studied, compared with 20% in 16 age-matched controls. The increase in blood monocytes was accompanied by a reciprocal decrease in mean blood DC percentage (from 0.42% of MNC in normal individuals to 0.16% of MNC in CMML patients). Absolute blood DC numbers showed a minimal (non-significant) reduction from 9.8 x 10(6)/l in normal individuals to 7.5 x 10(6)/l in CMML patients. The CD14(low) WCD16+ monocyte subpopulation was not found in CMML patients. After culture in GM-CSF/IL-4, CMML CD14+ monocytes acquired the phenotype of immature monocyte derived DC (Mo-DC) with similar yields to normal blood Mo-DC generation. Addition of TNF-alpha or LPS induced both normal and CMML Mo-DC to express prominent dendritic processes, the CMRF44+ and CD83+ antigens and high levels of HLA-DR, CD80 and CD86. Treatment either with TNF-alpha or LPS increased the allostimulatory activity of normal Mo-DC, but had little effect on the allostimulatory activity of CMML Mo-DC, perhaps reflecting the underlying neoplastic changes in monocyte precursors. We conclude that the blood DC numbers are relatively unaffected in CMML, suggesting discrete regulation of monocyte and DC production.     

Flow cytometry immunophenotypic findings in chronic myelomonocytic leukemia and its utility in monitoring treatment response

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic/myeloproliferative neoplasm, characterized by persistent monocytosis. Due to the lack of unique surface markers expressed by neoplastic monocytes and the frequent CD34‐negative blast immunophenotype, the diagnostic value of flow cytometric immunophenotyping (FCI) in CMML is rarely studied. In this study, by using a multicolor FCI assay, we assessed bone marrow (BM) immunophenotypical alterations in 118 CMML patients and follow‐up BM samples in 35 of these patients. The median BM monocytes as determined by FCI were 14% (1–63%), correlated with morphologic count (P = 0.0004). FCI alterations in monocytes were observed in 96% and granulocytes in 83% of cases. The percentage of CD34⁺ myeloblasts by FCI was low [median 0.6% (0.02–12.6%)], but exhibiting frequent aberrancies [median 6 (2–12)]. CD34⁺ B‐cell precursors were absent in 93% of cases. In 35 patients with follow‐up BM samples assessed, the CD34⁺ myeloblasts showed persistent FCI aberrancies in all 29 patients treated with hypomethylating agents and 3 patients on observation, but became normal in 3 patients following stem cell transplant. In conclusion, CMML exhibit numerous FCI alterations in monocytes, granulocytes, and more profound/frequent in CD34⁺ myeloblasts. These findings provide solid evidence for using FCI as an ancillary test in CMML diagnosis and also, in assessment of treatment responses.     

Incorporating flow cytometry and next-generation sequencing in the diagnosis of CMML. Are we ready for prime?

In the last version of the WHO classification of myeloid malignancies, flow cytometry and molecular investigation are listed as potentially useful, yet non-essential diagnostic tools in hard-to-recognize chronic myelomonocytic leukemias (CMML). Flow recognition of CMML was initially based on an increase in the fraction of peripheral blood, CD14⁺,CD16^- classical monocytes ≥94% of total monocytes. An associated inflammatory disease can preclude the detection of classical monocyte fraction increase by inducing accumulation of CD14⁺,CD16⁺ intermediate monocytes. In such a situation, decrease in the Slan⁺,CD14^low,CD16⁺ non-classical monocyte fraction below 1.7% still supports CMML diagnosis. This robust, two-step flow cytometry assay identifies CMML with a very high sensitivity. Otherwise, detection of one or several acquired gene mutations with high variant allele frequency supports the diagnosis of CMML, oligomonocytic CMML or clonal monocytosis of clinical significance. Together, recent investigations support integration of flow cytometry analysis of peripheral blood monocyte subsets and new generation sequencing of a panel of 20–30 recurrently mutated genes in the diagnostic work-up of CMML.     

Plasmacytoid dendritic cells proliferation associated with acute myeloid leukemia: phenotype profile and mutation landscape

Neoplasms involving plasmacytoid dendritic cells (pDC) include blastic pDC neoplasms (BPDCN) and other pDC proliferations, where pDC are associated with myeloid malignancies: most frequently chronic myelomonocytic leukemia (CMML) but also acute myeloid leukemia (AML), hereafter named pDC-AML. We aimed to determine the reactive or neoplastic origin of pDC in pDC-AML, and their link with the CD34+ blasts, monocytes or conventional DC (cDC) associated in the same sample, by phenotypic and molecular analyses (targeted next-generation sequencing, 70 genes). We compared 15 pDCAML at diagnosis with 21 BPDCN and 11 normal pDC from healthy donors. CD45low CD34+ blasts were found in all cases (10-80% of medullar cells), associated with pDC (4-36%), monocytes in 14 cases (1-10%) and cDC (two cases, 4.8-19%). pDC in pDC-AML harbor a clearly different phenotype from BPDCN: CD4+ CD56– in 100% of cases, most frequently CD303+, CD304+ and CD34+; lower expression of cTCL1 and CD123 with isolated lymphoid markers (CD22/CD7/CD5) in some cases, suggesting a prepDC stage. In all cases, pDC, monocytes and cDC are neoplastic since they harbor the same mutations as CD34+ blasts. RUNX1 is the most commonly mutated gene: detected in all AML with minimal differentiation (M0-AML) but not in the other cases. Despite the low number of cases, the systematic association between M0-AML, RUNX1 mutations and an excess of pDC is puzzling. Further evaluation in a larger cohort is required to confirm RUNX1 mutations in pDC-AML with minimal differentiation and to investigate whether it represents a proliferation of blasts with macrophage and DC progenitor potential.     

Aberrant expression of the major sialoglycoprotein (CD43) on the monocytes of patients with myelodysplastic syndromes

 CD43, a sialylated glycoprotein expressed on the surface of most hematopoietic cells, has been implicated in cell adhesion and signaling. The reduced expression of this antigen in patients with WiscottAldrich syndrome, in which progressive immunodeficiency is a major problem, raised the question whether abnormal expression of this molecule could affect the susceptibility to infections in patients with myelodysplastic syndromes (MDS). We studied the expression of this antigen on the monocytes of ten patients with chronic myelomonocytic leukemia (CMML) and compared the results with 67 patients suffering from other MDS syndromes and with 18 healthy individuals. We chose this series as it plays an important role in MDS patients where in most cases the neutrophils are defective. We also examined the following antigens as indicative of activation and adhesion of the monocytes in these patients: CD11b, CD18, CD35, CD38, CD44, CD69. We found decreased expression of CD43 on the monocytes of the RA, RAS, RAEB, and RAEB-t patients compared with the CMML and controls. The other activation molecules studied were found to be upregulated, suggesting the existence of activated monocytes in these patients. The increased levels of soluble vascular cell adhesion molecule in these patients suggest vascular endothelial activation in the absence of infection. Further experiments are needed to investigate the significance of CD43 downregulation in these patients, its role in cell adherence and tissue migration, and the correlation of the phenomenon to the increased susceptibility to infections observed in these patients. Received: 9 April 1999 / Accepted: 21 September 1999     

Increased subpopulations of CD16(+) and CD56(+) blood monocytes in patients with active Crohn's disease

BACKGROUND: Circulating monocytes may be subdivided according to the presence or absence of the Fcgamma receptor CD16 and the neural cell adhesion molecule CD56. Monocytes classified into these subpopulations are characterized by distinct phenotypic and functional features. We hypothesized that patients with active Crohn's disease differ in their peripheral monocyte subpopulations. METHODS: Using flow cytometry we investigated the expression of CD16 and CD56 on circulating monocytes in 11 patients with active Crohn's disease and 11 controls. These monocyte subpopulations were then analyzed for expression of the chemokine receptor fractalkine, CX(3)CR1, and the monocyte chemoattractant protein-1, CCR2. RESULTS: We found a median 3.7-fold increase in the number of CD16(+) monocytes related to the population with high expression of the pattern recognition receptor CD14 compared to that in the controls (P < 0.001). By studying the percentage of monocytes expressing CX(3)CR1, and their relative fluorescence intensity (RFI), we found significant differences, with both the highest percentage and the highest RFI in the CD14(low)CD16(+) subpopulation, whereas the CD14(high)CD16(+) subgroup represented an intermediate population. Inversely, CCR2 expression was highest in the populations with high expression of CD14, whereas the CD14(low)CD16(+) subpopulation showed the lowest percentage and the lowest RFI for CCR2. We found the percentage of CD14(+)CD56(+) monocytes in patients with active Crohn's disease to be increased 2.7 times compared to the controls (P = 0.011). CONCLUSIONS: These results show that subsets of peripheral monocytes with a more mature phenotype are expanded in patients with active Crohn's disease.     

Chromosome aberrations are restricted to the CD56+, CD3− tumour cell population in natural killer cell lymphomas: a combined immunophenotyping and FISH study

Natural killer (NK) cell lymphomas are a newly recognized entity of non-Hodgkin's lymphoma with a highly aggressive clinical course and strong association with Epstein-Barr virus (EBV) infection. Although no recurrent chromosome aberrations have been identified in NK-cell lymphoma, deletions of 6q and trisomy 7 have been described repeatedly in this type of lymphoma. In this study we attempted to determine the immunophenotypes of tumour cells with certain chromosome aberrations, i.e. deletions of 6q and trisomy 7, in three cases of NK cell lymphomas by means of combined immunophenotyping and fluorescence in situ hybridization (FISH). In all three cases clonal chromosome aberrations were detected only in CD56+ cells but not in CD3+ or CD5+ cells. However, not all CD56+ cells were shown to contain these chromosome aberrations. Double immunophenotyping combined with FISH confirmed that the chromosome aberrations occurred only in CD56+CD3- cells. This study indicates that chromosome aberrations in NK-cell lymphomas are restricted to the CD56+, CD3- and CD5- cell population and that NK-cell lymphomas are indeed derived from mature true NK cells and not from T lymphocytes.     

Review of phenotypic markers used in flow cytometric analysis of MGUS and MM,and applicability of flow cytometry in other plasma cell disorders

Flow cytometric immunophenotyping is considered an indispensable tool for the diagnosis, classification and monitoring of disease in monoclonal gammopathies. The clinical sensitivity of flow cytometry is comparable with advanced molecular methods. Clinical application of flow cytometry in monoclonal gammopathies has various dimensions, such as differential diagnosis of malignant plasma cell disorder from reactive plasmacytosis, identifying the progression risk in monoclonal gammopathy of undetermined significance (MGUS) and asymptomatic multiple myeloma (MM), and minimal residual disease detection. Flow cytometry‐based clonality assessment with immunophenotyping encourages and enables the most stringent method of diagnosis and follow‐up. The objective of this review is to update the malignant plasma cells phenotypic profile of MGUS and MM. The most comprehensive antigens, such as CD19, CD27, CD28, CD45, CD56 and CD117, play a significant role in the characterization of normal and malignant plasma cells. Several research groups described the putative phenotype of myeloma cell progenitors, but no remarkable suggestion could be made because of disparity. This review also focuses on the association of malignant phenotypic markers and chromosomal aberrations that identify the specific prognostic features in monoclonal gammopathies.     

Intracellular cytokine profile of cord and adult blood monocytes.

Cord blood (CB) transplantations are associated with low graft-versus-host disease (GVHD). The pathophysiology of GVHD involves interaction and activation of different cell types, as lymphocytes and monocytes, and results in a cascade of cytokine production. After antigen or mitogen stimulation, CB monocytes release lower levels of cytokines than adult blood (AB) monocytes. In this study, the detection of intracellular IL-1 beta and TNF-alpha produced by monocytes was evaluated in response to tuberculin PPD to investigate whether the reduced capacity of CB monocytes to secrete cytokines could be related to an impaired functional activity and to a particular phenotypic profile. Results showed that the percentage of CD64(+)monocytes producing intracellular IL-1 beta and TNF-alpha was significantly lower in CB and that the phenotypic profile of CB monocytes producing these cytokine (CD64(+)CD14(+)) was different to that of AB monocytes (CD64(+)CD14(+), CD64(+)CD33(+) and CD64(+) CD45RO(+)). These results suggest that the lower capacity of CB monocyte populations to produce IL-1 beta and TNF-alpha might be due to a functional immaturity of CB monocytes at the cellular level as reflected by the different phenotypic profile of CB monocytes.     

Phenotypic and functional characteristics of circulating monocytes of elderly persons

Aging is associated with impairment of immune functions. Age-dependent alterations in T-cells are well known. Although the pivotal role of monocytes in immune regulation by their production of proinflammatory and inhibitory cytokines is acknowledged, limited information is available on monocyte changes in aging. The present study focused on phenotypic changes in circulating monocytes in elderly subjects and in the level of cytokines they produce. The results demonstrated a significant expansion of CD14dim/CD16bright circulating monocytes in elderly. In contrast, the majority of circulating monocytes of healthy young individuals were CD14bright/CD16dim. The CD14dim/CD16bright monocytes are considered to have phenotypic evidence for activation. Furthermore, significant increases of constitutive production of monocytic cytokines including interleukin (IL)-1beta. IL-1 receptor antagonist, and IL-6 by nonstimulated monocytes from elderly was also indicative of activation. This was also observed when monocytes from elderly were cultured with autologous lymphocytes. However, after stimulation, significantly lowered IL-1beta production was observed and IL-6 and IL-10 tended to be higher in the elderly. Collectively, these results indicate that monocytes of aged individuals, in contrast to a younger population exhibit in vivo activation as well as imbalanced production of cytokines. Such age-related alterations in monocytes may contribute to impaired immune competence of aging.     

Ethanol and Natural Killer Cells. I. Activity and Immunophenotype in Alcoholic Humans

The human lymphocyte fraction with the greatest fresh killing activity against K562 targets is phenotypically the CD3⁻CD19⁻CD56⁺ subset There have been reports of reduced natural killer (NK) activity in human alcoholics, but overall consistency is lacking and phenotypic monitoring has been inadequate to allow reliable estimates of changes in the active cell fractions. We have evaluated a range of cell surface markers and fresh NK activity in controls and alcoholics, and now report abnormalities in both phenotype and function in some alcoholics, but a normal profile in others. Patients without evidence of active liver disease (AWLDs) tend to have normal fresh basal activities and phenotypic profiles. Patients with alcoholic liver disease (ALDs) have fewer Lin⁻ lymphocytes that are CD56⁺. Three of 14 ALDs assayed in the present work had absent NK activity, whereas others were activated. In normal controls and in AWLDs, the presence of monocytes in the lytic assay consistently inhibits lysis; but, in some patients with ALD, the presence of monocytes is stimulatoty to NK activity. In alcoholics as one group, there is a statistically significant dative increase in a novel Lin⁻ subset of unknown function; this subset has a phenotype of Lin⁻CD56⁻CD45RO⁺.     

Pleural involvement in the course of chronic myelomonocytic leukemia and the development of multiple colonic perforation due to leukemic infiltration in the acute leukemia phase

A 68-year-old man with chronic myelomonocytic leukemia (CMML) was initially treated with hydroxyurea with subsequent stable disease. In the time course, he developed bilateral pleuritis accompanied by leukocytosis and spiking fever. Cytologic analysis of the pleural effusion revealed abundant mature granulocytes and monocytes. He was treated with intravenous or oral etoposide with consequent resolution of the pleuritis, indicating the pleural involvement of CMML. Three months later, he developed hepatomegaly and became febrile. One month thereafter, the CMML transformed to acute myeloid leukemia, and the patient developed massive bloody stools associated with epigastric pain and leukocytosis. A gastrofiberscopic examination showed multiple bleeding gastric ulcers. The bleeding ulcers were treated with the clipping procedure; however, the bloody stools continued. Although intravenous etoposide was effective for the leukocytosis and hepatomegaly, the treatment did not improve the bloody stools. The patient finally died of panperitonitis. The autopsy showed multiple ulcers of the transverse colon, some of which were perforated. Microscopically, the ulcerated areas were densely infiltrated with leukemic cells predominantly consisting of immature monocytes and granulocytes. This patient may be the first reported case of CMML complicated by colonic perforation due to leukemic infiltration.     

Phenotypic and functional characteristics of circulating monocytes of elderly persons

Aging is associated with impairment of immune functions. Age-dependent alterations in T-cells are well known. Although the pivotal role of monocytes in immune regulation by their production of proinflammatory and inhibitory cytokines is acknowledged, limited information is available on monocyte changes in aging. The present study focused on phenotypic changes in circulating monocytes in elderly subjects and in the level of cytokines they produce. The results demonstrated a significant expansion of CD14dim/CD16bright circulating monocytes in elderly. In contrast, the majority of circulating monocytes of healthy young individuals were CD14bright/CD16dim. The CD14dim/CD16bright monocytes are considered to have phenotypic evidence for activation. Furthermore, significant increases of constitutive production of monocytic cytokines including interleukin (IL)-1beta. IL-1 receptor antagonist, and IL-6 by nonstimulated monocytes from elderly was also indicative of activation. This was also observed when monocytes from elderly were cultured with autologous lymphocytes. However, after stimulation, significantly lowered IL-1beta production was observed and IL-6 and IL-10 tended to be higher in the elderly. Collectively, these results indicate that monocytes of aged individuals, in contrast to a younger population exhibit in vivo activation as well as imbalanced production of cytokines. Such age-related alterations in monocytes may contribute to impaired immune competence of aging.     

Increased numbers of tumor-lysing monocytes in cancer patients

Lymphatic infiltration is a well known phenomenon in different tumors including endocrine malignancies. However, little is known about the role of antigen-presenting cells and T cell activation in this context. The aim of our study was to investigate the quantity and function of CD14+/CD56+ monocytes in tumor patients including endocrine malignancies. First, these cells were characterized in peripheral blood of endocrine and non-endocrine cancer patients as well as in tumor tissue samples. Cancer patients had in mean 3.7 times more CD14+/CD56+ monocytes in the peripheral blood compared to healthy controls (p≤0.0001), while the highest frequencies were seen in patients with heavy tumor load. Importantly, these cells additionally expressed several NK cell markers. A proof of CD14+/CD56+ infiltrations into papillary thyroid carcinoma was shown by immunohistochemical analyses. Functional analyses revealed an apoptosis inducing capacity in vitro after IFN-α re-stimulation. Our data indicate the importance of tumor-lysing monocytes in antitumor immunity.     

Impact of immunophenotype on prognosis of patients with myelodysplastic syndromes. Its value in patients without karyotypic abnormalities

The aim of this study was simultaneously to evaluate the potential influence of cytogenetic, immunophenotypic and cell culture studies in the evolution of the myelodysplastic syndromes (MDS) with particular attention to the value of the two latter features in predicting the outcome of those patients in which karyotypic information is normal or not available. A series of 77 newly diagnosed patients with primary MDS were analyzed. Immunophenotypic studies were carried out by flow cytometry in triple color combinations: CD34/CD33/CD38, CD15/CD34/HLADR and HLADR/CD13/CD45. In all, 63% of patients showed a normal karyotype and 37% showed clonal abnormalities. In immunophenotypic analysis, overall 90% of patients displayed phenotypic aberrations and 60% showed two or more aberrations. In univariate analysis, 10 variables had a significant influence on survival: >10% bone marrow (BM) blast cells, >or=peripheral blood (PB) cytopenias, >2% of BM CD34+ cells, >85% of BM myeloid cells, >7% monocytic cells, <49% of neutrophils, a neutrophil/monocytic cell ratio <7, more than three phenotypic aberrations and >80 colony-forming units for granulocytes and macrophages (CFU-GM)/10(5) plated cells. Only the presence of >or=5% of BM blast cells (P=0.001) and cytogenetic subgroups (P=0.008) showed independent prognostic significance by multivariate analysis. In patients lacking cytogenetic information or in which the karyotype was normal additional markers had an independent prognostic value in multivariate analysis: >or=2 phenotypic aberrations (P=0.001) and >or=2 PB cytopenias (P=0.004). In summary, our results show that in patients in whom the karyotype is normal or where an insufficient amount of mitoses is obtained, immunophenotype could help to establish a prognosis.     

A case of chronic myelomonocytic leukemia who developed pericardial effusion during stably controlled leukocytosis

We report a rare case of chronic myelomonocytic leukemia (CMML) with pericardial effusion. After receving the diagnosis of CMML, she had been successfully treated with hydroxycarbamide (HU). However, she was admitted to our hospital due to pericardial effusion. The majority of the cells in the pericardial fluid were monocytes. We made the diagnosis of pericardial involvement with CMML cells and intravenously administered etoposide (100 mg/body daily for 5 days). Although CMML cells disappeared from the peripheral blood, the pericardial effusion still persisted. This case indicates that pericardial effusion is a possible and life-threatening complication in CMML patients despite stably controlled leukocytes.     

Detection of CD55- and CD59-deficient granulocytic populations in patients with myelodysplastic syndrome

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by absence of CD55 and CD59 from the surface of affected cells. PNH has been associated with myelodysplastic syndromes (MDS). The aim of our study was to estimate the prevalence of the PNH clone in MDS patients by detecting CD55 and CD59 deficiency. We studied 90 MDS patients: 19 patients with RA, 15 with refractory anemia with ringed sideroblasts (RARS), 18 with refractory anemia with excess of blasts (RAEB), 17 with refractory anemia with excess of blasts in transformation (RAEB-t), and 21 with chronic myelomonocytic leukemia (CMML). Twenty healthy individuals were also studied as the control group. We studied the PNH clone on granulocytes of these patients with the aid of flow cytometry. CD55- and CD59-deficient granulocytic populations were detected in 15.5% of MDS patients compared to 2.8% of normal individuals. Among the subgroups of the study, significant difference was present in three cases: (1) between CMML and control, (2) between CMML and RA, and (3) between CMML and RARS. These data indicate a possible association between PNH phenotype and MDS. MDS patients of worse prognosis (CMML) express more strongly the PNH clone compared to those of better prognosis (RA and RARS). Perhaps, the examination of MDS patients for the PNH clone by flow cytometry could provide us with a valuable prognostic tool.     

A clinical study on myelodysplastic syndrome. Report of 64 cases

Systematic clinical and laboratory observations of 64 cases of myelodysplastic syndrome (MDS) were made. The results showed that malignant clone already exists in the bone marrow of patients with MDS. Eighteen cases of them have transformed into AML. The rates of transforming into AML in RAEB, RAEB-T and CMML were markedly higher than that in RA. The courses of MDS which transformed into AML from the various types were different. The transformation in RA was obviously longer than those in RAEB and RAEB-T. Two cases transformed into myelofibrosis. Diagnosis of CMML according to the FAB classification criteria revealed that it has two forms. One shows only increase of mature monocytes and it has no relation with the types of acute leukemia to be transformed. It is considered as a reactive monocytosis. The other form, in addition to increase of mature monocytes, also has increase of a few monoblasts and promonocytes. These are considered as true CMML and usually quickly developed into M4 or M5 which are related with monocytes.     

Patients with high-risk myelodysplastic syndrome can have polyclonal or clonal haemopoiesis in complete haematological remission

The clonality of mature peripheral blood-derived myeloid and lymphoid cells and bone marrow haemopoietic progenitors from 18 females with myelodysplasia (MDS) (five refractory anaemia, RA; one RA with ringed sideroblasts, RARS; three chronic myelomonocytic leukaemia, CMML; four RA with excess of blasts, RAEB; five RAEB in transformation, RAEB-t) was studied by X-chromosome inactivation analysis. Using the human androgen-receptor (HUMARA) assay, we analysed the clonal patterns of highly purified immature CD34⁺38^? and committed CD34⁺38⁺ marrow-derived progenitors, and CD16⁺14^? granulocytes, CD14⁺ monocytes, CD3⁺ T and CD19⁺ B lymphocytes from peripheral blood. In high-risk patients (RAEB, RAEB-t), clonality analysis was performed before and after intensive remission-induction treatment. All patients, except one with RA, had predominance of a single clone in their granulocytes and monocytes. The same clonal pattern was found in CD34⁺ progenitor cells. In contrast, CD3⁺ T lymphocytes were polyclonal or oligoclonal in 14/18 patients. X-chromosome inactivation patterns of CD19⁺B cells were highly concordant with CD3⁺ T cells except for two patients (one RA, one CMML) with monoclonal B and polyclonal T lymphocytes, therefore suggesting a clonal mutation in a progenitor common to the myeloid and B-lymphoid lineages or the coexistence of MDS and a B-cell disorder in these particular patients. After high-dose non-myeloablative chemotherapy, polyclonal haemopoiesis was reinstalled in the mature myeloid cells and immature and committed marrow progenitors in three of four patients achieving complete haematological remission. Therefore we conclude that most haematological remissions in MDS are associated with restoration of polyclonal haemopoiesis.