血液肿瘤患者FLT3/ITD基因突变的检测及临床意义

目的检测血液肿瘤患者FLT3/ITD基因突变,探讨其突变的临床意义。方法2001—2005年对南方医科大学南方医院血液科332例血液肿瘤患者,采用聚合酶链反应(PCR)方法检测FLT3/ITD基因突变。结果FLT3/ITD基因突变阳性率分别为急性髓性白血病(AML)22.3%(23/103)、慢性髓性白血病急变期(CML-BC)6.5%(2/31)、骨髓增生异常综合征(MDS)5.6%(2/36)和急性淋巴细胞白血病(ALL)2.6%(2/76)。而慢性髓性白血病慢性期(CML-CP)、慢性淋巴细胞白血病(CLL)、多发性骨髓瘤(MM)和非霍奇金淋巴瘤(NHL)均未发现FLT3/ITD基因突变。FLT3/ITD基因突变阳性AML患者外周血WBC计数及骨髓白血病细胞比例显著高于FLT3/ITD基因突变阴性AML患者(P<0.05),FLT3/ITD基因突变阳性AML患者完全缓解后18个月内累计复发率(63.6%)显著高于FLT3/ITD基因突变阴性AML组(27.7%)(P<0.05)。结论FLT3/ITD基因突变检测对血液肿瘤预后有一定意义;FLT3/ITD基因突变AML患者预后差。     

Non-Hodgkin's lymphoma and other nonhepatic malignancies in Swedish patients with hepatitis C virus infection

The aim of this study was to evaluate the association between hepatitis C virus (HCV) infection and non-Hodgkin's lymphoma (NHL), multiple myeloma (MM), thyroid cancer (TC), chronic lymphatic leukemia (CLL), acute lymphatic leukemia (ALL), and Hodgkin's lymphoma (HL). A Swedish cohort of 27,150 HCV-infected persons notified during 1990-2000 was included in the study. The database was linked to other national registers to calculate the observation time, expressed as person-years, and to identify all incident malignancies in the cohort. The patients were stratified according to assumed time of previous HCV infection. The relative risk of malignancy was expressed as a standardized incidence ratio (SIR)-the observed number compared to the expected number. During 1990-2000 there were 50 NHL, 15 MM, 14 ALL, 8 TC, 6 CLL, and 4 HL diagnoses in the cohort. Altogether, 20 NHL, 7 MM, 5 TC, 4 CLL, 1 ALL, and 1 HL patient fulfilled the criteria to be included in the statistical analysis. The observation time was 122,272 person-years. The risk of NHL and MM was significantly increased in the stratum with more than 15 years of infection (SIR 1.89 [95% CI, 1.10-3.03] and 2.54 [95% CI, 1.11-5.69], respectively). The association was not significant in TC or CLL. In conclusion, we report the incidence of several malignancies in a nationwide cohort of HCV-infected persons. Although the delayed diagnosis of HCV probably has resulted in an underestimation of the risk, this study showed a significantly increased risk of NHL and MM.     

A single monoclonal antibody identifies T-cell lineage of childhood lymphoid malignancies

Immunophenotyping studies with monoclonal antibodies have revealed the heterogeneity of childhood acute lymphoblastic leukemia (ALL) and non- Hodgkin's lymphoma (NHL). The lymphoid malignancies of T-cell lineage are particularly heterogeneous and, until now, no single monoclonal antibody has been found to identify all cases of T-ALL and T-NHL. A monoclonal antibody, 4H9, recognizes an antigen of 40,000 molecular weight on normal and malignant T cells. Thirty-six cases of childhood T- ALL and T-NHL were tested, and in all cases, the malignant blast cells were reactive with 4H9, whereas malignant cells from 61 cases of non-T ALL and NHL were not reactive with 4H9. Monoclonal antibody 4H9 is a sensitive and specific reagent for the identification of childhood T- cell ALL and NHL and should be extremely useful in immunophenotyping studies of lymphoid malignancies.     

Stimulation of growth of human malignant lymphoma and lymphoid leukemia cells in vitro

Summary We have analyzed cultures of malignant lymphoma cells and cells from patients with acute lymphoid leukemia in methylcellulose for their ability to from colonies. Clonogenic growth was examined in the presence or absence of fetal calf serum (FCS), platelet-poor plasma (PPP), medium conditioned by phytohemagglutininstimulated leukocytes (PHA-LCM), or irradiated allogeneic bone marrow stroma cells. Cells from 25 lymphoma patients — 17 with non-Hodgkin's lymphoma (NHL), eight with Hodgkin's disease (HD) — and from 19 patients with acute lymphocytic leukemia (ALL) were investigated. We show that colony growth can be obtained in a minority of cases (in 3 NHL, 5 HD, and 2 ALL) and that the use of FCS and allogeneic irradiated stroma cells may be required for optimal colony formation.This work was supported by theDeutsche Forschungsgemeinschaft (Str 250/2-2).     

自体外周血干细胞移植治疗血液恶性肿瘤231例临床观察

目的观察自体外周血干细胞移植(APBSCT)治疗血液恶性肿瘤的疗效。方法2001年3月至2007年2月对第三军医大学新桥医院231例血液恶性肿瘤患者施行APBSCT,其中急性淋巴细胞白血病(ALL)45例,急性髓性白血病(AML)34例,非霍奇金淋巴瘤(NHL)100例,霍奇金淋巴瘤(HD)31例,多发性骨髓瘤(MM)21例,观察临床疗效和并发症。结果除1例ALL外,230例患者移植后造血功能均快速重建。ALL首次完全缓解(CR1)28例患者中无病存活(DFS)13例,带病存活4例,死亡11例;ALL二次缓解(CR2)17例患者中DFS3例,带病存活4例,死亡10例。AMLCR120例患者中DFS11例,带病存活3例,死亡6例;AMLCR214例患者中DFS6例,带病存活2例,死亡6例。NHLCR159例患者中DFS43例,带病存活7例,死亡9例;NHLCR230例患者中DFS18例,带病存活5例,死亡7例;NHL未缓解(NR)11例患者中DFS2例,带病存活4例,死亡5例。HDCR110例患者中DFS10例;HD部分缓解(PR)15例患者中DFS12例,带病存活3例;HD疾病复发(RE)6例患者中DFS3例,带病存活2例,死亡1例。MM21例患者中DFS7例,带病存活6例,死亡8例。结论APBSCT是一种安全有效的血液肿瘤治疗方法。     

Leukemia-associated antigens in ALL.

A cytotoxic common ALL antiserum (CALLA) specific for leukemic cells of most patients with non-T-cel- acute lymphoblastic leukemia (ALL) and of some patients with chronic myelogenous leukemia (CML) in blast crisis has been reproducibly prepared using cell lines for absorption. CALLA reacts with leukemic cells of 110 of 134 patients (82%) with non-T-cell ALL; 1 of 71 (1%) patients with acute myelogenous leukemia (AML); 2 of 7 patients (29%) with chronic myelogenous leukemia in blast crisis; 7 of 92 patients (8%) with other hematologic malignancies; and with the leukemic cell lines Laz 221 and NALM-1. It does not react with the normal hematopoietic cells, B- or T-cell lines, or cells from 26 patients with T-cell ALL that were tested. CALLA reactivity and periodic acid Schiff (PAS) staining correlate poorly, with CALLA reacting with cells from 86% (64 of 74) of patients with PAS-positive and 76% (29 of 38) of those with PAS-negative non-T-cell ALL. In these patients, CALLA reacts with cells from 89% of those under age 12 (78 of 88); 74% of those aged 12--20 (20 of 27); and 58% of those over 20 (11 of 19). Using only CALLA and antisera specific for Ia-like and T-cell antigens, we can now distinguish most cases of ALL from AML and other hematologic malignancies.     

Serum ferritin in hematologic malignancies

Serum ferritin was measured in a variety of hematologic malignancies at presentation, in remission following therapy, and in relapse. Ferritin was strikingly increased in all acute leukemias at presentation and in relapse, in the blastic crisis of CML, and in smouldering leukemia. Remission in both ALL and ANLL was associated with a reduction of serum ferritin, and this normalization was a function of remission duration. In the malignant lymphomas serum ferritin was related to tumor histology. Highest levels were found in Hodgkin disease and histiocytic lymphoma, normal levels in lymphocytic lymphoma, and intermediate levels in mixed histiocytic-lymphocytic lymphoma. In all cases, remission was associated with normalization of serum ferritin. These correlations suggest that serum ferritin measurements may be of clinical usefulness in the initial evaluation and in the assessment of response to therapy in patients with acute leukemia and malignant lymphoma.     

A phase 1 trial of donor lymphocyte infusions expanded and activated ex vivo via CD3/CD28 costimulation

Donor lymphocyte infusions (DLIs) induce potent graft versus tumor (GVT) effects for relapsed chronic myelogenous leukemia (CML) after allogeneic stem cell transplantation (SCT) but are disappointing for other diseases. Disease resistance can occur if donor T cells are not appropriately activated in vivo. Ex vivo T-cell activation might overcome disease-induced anergy and augment GVT activity. We performed a phase 1 trial of ex vivo-activated DLI (aDLI) for 18 patients with relapse after SCT. Activated donor T cells are produced through costimulation with anti-CD3- and anti-CD28-coated beads. Patients with aggressive malignancies received induction chemotherapy, and all patients received conventional DLI (median, 1.5 x 10(8) mononuclear cells/kg) followed 12 days later by aDLI. Activated DLI was dose escalated from 1 x 10(6) to 1 x 10(8) CD3+ cells per kilogram in 5 levels. Seven patients developed acute graft versus host disease (GVHD) (5 grade I-II, 2 grade III), and 4 developed chronic GVHD. Eight patients achieved complete remission, including 4 of 7 with acute lymphocytic leukemia (ALL), 2 of 4 with acute myelogenous leukemia (AML), 1 with chronic lymphocytic leukemia (CLL), and 1 of 2 with non-Hodgkin lymphoma (NHL). Four complete responders relapsed while 4 remain alive in remission a median 23 months after aDLI. Overall, 10 of 18 remain alive 11 to 53 months after aDLI. Adoptive transfer of costimulated activated allogeneic T cells is feasible, does not result in excessive GVHD, and may contribute to durable remissions in diseases where conventional DLI has been disappointing.     

Mixed-lineage leukemia revisited: acute lymphocytic leukemia with myeloperoxidase-positive blasts by electron microscopy

Seven adult patients with untreated acute lymphocytic leukemia (ALL) who manifested 5% to 40% myeloperoxidase (MPO)-positive blasts by electron microscopy (EM) are reported. Six patients had an L2 morphology, and one had an L1 morphology by the French-American-British (FAB) classification. The immunophenotype was T cell in four patients. Molecular analysis showed rearrangement of the immunoglobulin JH in four patients, three of them also having rearrangement of the T-cell receptor beta or gamma. Induction chemotherapy with vincristine-doxorubicin-dexamethasone (VAD) produced a complete remission in five of six patients (83%). Our findings suggest the existence of a previously undescribed subtype of mixed-lineage leukemia, which by morphology and immunophenotype often appears as T-cell ALL but exhibits MPO-positive blasts by EM.     

Significance of minimal residual disease in lymphoid malignancies

Modern treatment protocols lead to complete remission (CR) in a considerable proportion of patients with lymphoproliferative disorders. However, many of these patients ultimately relapse, implying that achievement of a clinical CR is compatible with significant amounts of residual malignant cells. Cytogenetic, molecular and immunological techniques that are more sensitive than morphology are increasingly used to assess and quantify minimal residual disease (MRD). Immunological marker analysis allows the detection of aberrant or unusual immunophenotypes, PCR techniques target fusion regions of chromosome aberrations and clone-specific immunoglobulin and T-cell receptor gene rearrangements. The rationale underlying MRD studies is to improve measurement of treatment response, to provide independent prognostic information and to optimise therapeutic strategies. In acute lymphoblastic leukemia (ALL), the MRD based evaluation of initial response to front-line therapy emerged as a highly relevant diagnostic tool, particularly in childhood ALL, where MRD has been shown to be an independent prognostic factor allowing a precise risk group classification. In patients with chronic lymphocytic leukemia (CLL) and non-Hodgkin's lymphoma (NHL) the prognostic significance of MRD is still a matter of debate, as the majority of patients remain MRD positive after conventional treatment. This phenomenon has changed with the implementation of new treatment modalities, such as application of monoclonal antibodies, where a significant proportion of patients with NHL converts to MRD negativity and experiences prolonged remission. Whether this molecular remission will translate into a superior overall survival is currently the goal of ongoing prospective studies.     

The single cell gel electrophoresis: a potential tool for DNA analysis of the patients with hematological malignancies

Single cell gel electrophoresis (SCGE) was used to evaluate the level of DNA damage in peripheral blood (PB), bone marrow (BM), and lymphatic node (LN) cells of patients with acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), chronic myeloid leukemia (CML) and non-Hodgkin's lymphoma (NHL). The level of DNA damage was compared with the level of basal DNA damage in control group, represented by healthy donors. Statistically significant increase of basal DNA damage was found in leukemia/lymphoma cells of patients suffered from AML, CML, ALL of T-cell subtype (T-ALL), and NHL, however, no difference in basal DNA damage was found in patients with ALL of early B-cell subtype (B-ALL) and CLL in comparison to control group. The mean basal DNA damage increased in the order CLL相似文献   

Relapse risk in patients with malignant diseases given allogeneic hematopoietic cell transplantation after nonmyeloablative conditioning

Allogeneic hematopoietic cell transplantation (HCT) after nonmyeloablative conditioning for hematologic malignancies depends on graft-versus-tumor effects for eradication of cancer. Here, we estimated relapse risks according to disease characteristics. Between 1997 and 2006, 834 consecutive patients (median age, 55 years; range, 5-74 years) received related (n = 498) or unrelated (n = 336) HCT after 2 Gy total body irradiation alone (n = 171) or combined with fludarabine (90 mg/m(2); n = 663). Relapse rates per patient year (PY) at risk, corrected for follow-up and competing nonrelapse mortality, were calculated for 29 different diseases and stages. The overall relapse rate per PY was 0.36. Patients with chronic lymphocytic leukemia (CLL) and multiple myeloma (MM) in remission (CR), low-grade or mantle cell non-Hodgkin lymphoma (NHL) (CR + partial remission [PR]), and high-grade NHL-CR had the lowest rates (0.00-0.24; low risk). In contrast, patients with advanced myeloid and lymphoid malignancies had rates of more than 0.52 (high risk). Patients with lymphoproliferative diseases not in CR (except Hodgkin lymphoma and high-grade NHL) and myeloid malignancies in CR had rates of 0.26-0.37 (standard risk). In conclusion, patients with low-grade lymphoproliferative disorders experienced the lowest relapse rates, whereas patients with advanced myeloid and lymphoid malignancies had high relapse rates after nonmyeloablative HCT. The latter might benefit from cytoreductive treatment before HCT.     

Infectious complications after autologous hematopoietic stem cell transplantation: comparison of patients with acute myeloid leukemia,malignant lymphoma,and multiple myeloma

It is yet undetermined whether patients with different hematological malignancies have different propensities to infectious complications after high-dose chemotherapy (HDC) and autologous hematopoietic stem cell transplantation (HSCT). We retrospectively analyzed 136 cycles of HDC and autologous HSCT in 114 patients with acute myeloid leukemia (AML, 24 cycles), non-Hodgkin's lymphoma/Hodgkin's disease (NHL/HD, 55 cycles), and multiple myeloma (MM, 57 cycles) with respect to early infectious complications. Median duration of neutropenia was longer in patients with AML and NHL/HD than in patients with MM (11 days vs 8 days) and after conditioning including total body irradiation (TBI) compared with chemotherapy only preparative regimens (11 days vs 7 days). Fever requiring antimicrobial therapy was observed in 88 percent of cycles, with fever of unknown origin (FUO) accounting for 60 percent of febrile episodes. There was no proven fungal infection, but one case of probable invasive pulmonary aspergillosis. Microbiologically documented infections were seen in 29 percent and clinically documented infections in 11 percent. Response to first-line empirical antibiotic therapy was better for FUO than for documented infections (70 percent vs 40 percent). Patients with TBI as part of their conditioning regimen had more overall infections than patients without TBI (96 percent vs 82 percent). There were no differences with respect to the type or incidence of infections between patients with AML, NHL/HD, and MM. Patients with different hematological malignancies have similar rates of early infectious complications after HDC and autologous HSCT. TBI may be associated with an increased risk for infections in the early post-transplant period.     

Influence of acute and chronic graft-versus-host disease on relapse and survival after bone marrow transplantation from HLA-identical siblings as treatment of acute and chronic leukemia [published erratum appears in Blood 1989 Aug 15;74(3):1180]

To assess the influence of graft-versus-host disease (GVHD) on recurrent leukemia and survival after allogeneic marrow transplantation, we studied 1,202 patients with acute nonlymphocytic leukemia (ANL), acute lymphocytic leukemia (ALL), and chronic myelogenous leukemia (CML) given unmodified marrow grafts from HLA- identical siblings. Proportional hazards regression models using acute GVHD and chronic GVHD as time-dependent covariates demonstrated a significant association of GVHD with a decreased relative risk (RR, 0.33 to 0.42) of relapse in patients with ANL, ALL, and CML transplanted in advanced disease. Among patients developing either acute or chronic GVHD, treatment failure (that is, mortality or relapse) was decreased in patients with ALL transplanted in relapse (RR = 0.70, P less than .033) and CML in blast crisis (RR = 0.37, P less than .009). This effect was independent of age, sex, preparative regimen, GVHD prophylaxis, or length of follow-up. Five-year actuarial estimates were derived for the subset of 657 patients who survived in remission 150 days after transplant and were at risk for development of chronic GVHD. Among patients with ANL in first remission or CML in chronic phase, GVHD had an adverse effect on survival and no apparent influence on relapse. Among patients with ANL and ALL transplanted in relapse, the probability of relapse after day 150 was 74% without [corrected] GVHD, 45% with acute and chronic GVHD, 35% with [corrected] only acute GVHD, and 34% with only chronic GVHD (P less than .001). Actuarial survival in these four GVHD groups was 25%, 34%, 59%, and 62%, respectively (P less than .009). Among patients with CML in acceleration or blast crisis, the probability of relapse after day 150 was 65% without GVHD and 36% with acute and/or chronic GVHD (P less than .017). We conclude that acute and chronic GVHD were associated with a durable antileukemic effect and improved survival in patients transplanted in advanced stages of ALL and CML.     

Adenosine deaminase and ecto-5''-nucleotidase activities in various leukemias with special reference to blast crisis: significance of ecto-5''-nucleotidase in lymphoid blast crisis of chronic myeloid leukemia

Adenosine deaminase (ADA) and ecto-5'-nucleotidase (5'-N) activities were examined in peripheral leukocytes from patients with leukemias, including nine patients with chronic myeloid leukemia (CML) in blast crisis. Four of none cases of CML in blast crisis were myeloid and the remaining lymphoid morphologically. The diagnosis of CML in lymphoid blast crisis was further contributed by the measurement of terminal deoxynucleotidyl transferase (TdT) activity. In all four cases of lymphoid blast crisis and one of myeloid blast crisis, leukemia cells had high 5'-N activity, while there was a little or no detectable activity in those from four cases of myeloid blast crisis and all of CML in chronic phase. ADA activity was high in seven of nine patients with blast crisis. Taken together, leukemia cells from two cases of lymphoid blast crisis had high ADA and 5'-N activities comparable to those in acute lymphocytic leukemia (ALL) cells. In contrast, the enzyme activities of leukemia cells from all but one patient in myeloid blast crisis were in a range similar to acute myeloid leukemia cells. The implications of these findings are as follows: (1) 5'-N may be used as a new biochemical marker of CML in lymphoid blast crisis. (2) Some lymphoid cells of CML in blast crisis have high ADA, 5'-N, and TdT activities and thus are very similar to ALL cells.     

多种血液肿瘤中NK细胞受体表达差异的临床意义

目的：检测几种血液肿瘤患者中自然杀伤（NK）细胞受体变化，以探究NK细胞功能状态。方法：收集多发性骨髓瘤（MM）患者38例，其中IgG-k型18例、IgG-λ型10例、IgA-k型4例、IgA-λ型6例；非霍奇金淋巴瘤（NHL）患者27例，其中弥漫性大B细胞淋巴瘤18例、边缘区淋巴瘤3例、滤泡性淋巴瘤1例、套细胞淋巴瘤2例、免疫母性T细胞淋巴瘤1例、外周T细胞淋巴瘤2例；慢性髓系细胞白血病（CML）患者10例；30例健康志愿者为正常对照组。通过流式细胞术测定外周血中NK细胞占有核细胞比例，用实时荧光定量聚合酶链反应（RT-qPCR)方法检测NK细胞表面抑制性受体（PD-1）及活化性受体（CD69、NKG2D）的基因表达水平。结果：与正常对照组比较，MM、NHL患者外周血NK细胞占有核细胞比例比较，差异无统计学意义（P均＞0.05）；而CML患者NK细胞占有核细胞数显著减少（P＜0.05）；MM、NHL及CML患者的NK细胞表面活化性受体（CD69、NKG2D）水平较正常对照组明显降低，NK细胞表面抑制性受体（PD-1）表达显著高于正常对照组（P均＜0.05）；MM、NHL及CML患者间受体(PD-1、CD69、NKG2D)表达比较，差异无统计学意义（P均＞0.05）。结论：MM、NHL及CML患者外周血NK细胞表面活化性受体（CD69、NKG2D）水平明显降低，抑制性受体（如PD-1）表达明显增高，提示NK细胞功能耗竭。     

Non-Hodgkin's lymphomas of low-grade malignancy with particular reference to the lymphocytic lymphomas of B-cell origin (author's transl)]

More than two thirds of all non-Hodgkin's lymphomas (NHL) are of low-grade malignancy. This group comprehends five histological types: lymphocytic, immunocytic, plasmacytic, centrocytic, and centroblastic-centrocytic lymphomas. The lymphocytic lymphomas are second in frequency among the biopsies. The most common lymphocytic lymphoma is the chronic lymphocytic leukemia (CLL). It is characterized by the proliferation of small lymphocytes. The quantity and arrangement of the constantly present paraimmunoblasts and prolymphocytes allow to distinguish three histological subtypes of CLL. CLL, prolymphocytic leukemia, and hairy cell leukemia may be composed of B- or T-cells. Mycosis fungoides, Sézary's syndrome and T-zone lymphomas are T-cell lymphomas. All NHL of low-grade malignancy show a proliferation of small to medium sized lymphoid cells. Some large blast forms may be intermingled among these smaller cells. The inhomogeneity of low-grade malignant lymphomas with regard to the size of predominant cells and the admixture of blast forms determine the higher ("intermediate") degree of malignancy of some types in the group of low-grade malignant lymphomas. The overgrowth of the intermingled blast forms probably leads to the transformation into a lymphoma of high-grade malignancy. This event happens in variable frequency in the various types of low-grade malignant lymphomas. NHL of low-grade malignancy occur almost exclusively in adults, whereas the high-grade malignant lymphomas are found in all age-groups.     

Interleukin-3 receptor alpha chain (CD123) is widely expressed in hematologic malignancies.

BACKGROUND AND OBJECTIVES: The hematopoietic system is controlled by growth factors (cytokines) which can influence cell survival, proliferation, differentiation and functional activation. The study of cytokine receptor expression by flow cytometry could allow us to differentiate between normal and tumoral cells. DESIGN AND METHODS: We analyzed the expression of the interleukin-3 (IL-3) receptor a chain (CD123) in 22 normal samples and in a wide panel of hematologic malignancies using flow cytometry. We found that CD123 was expressed in the myeloid progenitor subpopulation but in contrast, normal lymphoid progenitors lacked CD123. We analyzed the CD123 expression pattern in 64 patients with acute leukemia, 45 with acute myeloid leukemia (AML) and 19 with acute lymphocytic leukemia (ALL) (13 B-cell lineage ALL and 6 T-cell lineage ALL). RESULTS: All the AML cases except two patients with M7 and all the B-cell lineage ALL patients were CD123 positive. In contrast, all the T-cell lineage ALL cases tested were CD123 negative. We also studied the CD123 expression pattern in 122 patients with a B-cell chronic lymphoproliferative disease (B-CLPD). CD123 was positive in three situations: 1) typical cases of hairy cell leukemia showed a specific, strong CD123 expression, 2) a subgroup of atypical chronic lymphocytic leukemia with a marked CD11c expression was also CD123 positive, and finally 3) transformed B-CLPD showed the phenomenon of transition from CD123 negativity to CD123 positivity simultaneuosly with morphologic changes. INTERPRETATION AND CONCLUSIONS: In summary, our data show high expression of IL-3 receptor a chain in hematologic malignancies. Given the high frequency of CD123 reactivity in blast cells in contrast to in normal precursors, this antigen could be applied to the study of minimal residual disease in acute leukemia. CD123 is expressed with a characteristic pattern in cases of hairy cell leukemia.