Usefulness of anti-CD117 in the flow cytometric analysis of acute leukemia

We assessed the diagnostic usefulness of adding anti-CD117 to our existing flow cytometric profile in the analysis of 150 consecutive cases of acute leukemia (de novo or relapsed acute myelogenous leukemia [AML], AML arising in myelodysplastic syndrome, blast crisis of chronic myelogenous leukemia [CML], acute lymphoblastic leukemia, acute unclassifiable leukemia, and biphenotypic leukemia). CD117 was expressed on more than 10% of blasts in 64% of de novo AMLs (42/66), 95% of relapsed AMLs (19/20), 75% of AMLs arising from a myelodysplastic syndrome (6/8), and 25% of myeloid blast crisis in CMLs (1/4). CD117 was not expressed in acute lymphoblastic, acute biphenotypic, or unclassified leukemia or lymphoid blast crisis of CML. The specificity, positive predictive value, sensitivity, and negative predictive value of CD117 for AML were 100%, 100%, 69%, and 62%, respectively. CD117 is a specific marker for myeloblastic leukemias. Sensitivity is greatest in French-American-British M2 and relapsed AML. Intensity of CD117 expression is dim. Despite the high specificity and positive predictive value, the addition of anti-CD117 to our panel did not prove essential for the assignment of blast lineage.     

Immunophenotyping of acute leukemias using paraffin-embedded tissue sections

In a study of 55 patients with either acute lymphoid leukemia (ALL; 25 cases) or acute myeloid leukemia (AML; 30 cases), paraffin-embedded bone marrow particle sections were examined with a panel of monoclonal and polyclonal antibodies reactive toward lymphoid and myeloid-associated antigens, using the alkaline phosphatase-anti-alkaline phosphatase (APAAP) technique. All cases were previously classified according to the French-American-British (FAB) Co-operative Group, and cases of ALL were immunophenotyped by flow cytometry. Results indicated that myeloid-associated antibodies (Mac 387, KP 1 [CD68], antielastase, antilactoferrin, and antilysozyme) did not react with any case of ALL, M1-AML, or M6-AML, whereas at least one of these antibodies reacted with 20 of 21 (95%) cases of M2, M3, M4, and M5-AML. Anti-glycophorin C marked cases of M6-AML, whereas anti-CD3 labeled T-cell ALL. None of the antibodies tested specifically identified cases of B-cell ALL. The authors conclude that use of a selected panel of antibodies on paraffin-embedded bone marrow particle sections may be of value in the diagnosis and immunophenotypic classification of many cases of acute leukemias.     

CD44 and CD27 delineate B-precursor stages with different recombination status and with an uneven distribution in nonmalignant and malignant hematopoiesis

The expression of CD27 and CD44 correlate with the genotype of B-precursor acute lymphoblastic leukemia (ALL). Based on the expression of these antigens, we identified counterparts of TEL/AML1(pos) and TEL/AML1(neg) leukemic cells in nonmalignant bone marrow. Although CD27 is known as a marker of mature memory B cells, we recently showed that CD27 is also expressed by malignant and nonmalignant B precursors. Here, we show that CD27 and CD44 delineate stages of B-precursor development. Well-established differentiation markers showed that the developmental sequence starts from undetermined progenitors, expressing CD44. Upon B-lineage commitment, cells gain CD27 and lose CD44. The CD27(pos)CD44(neg) (CD27 single positive, 27SP) cells are the earliest stage within CD10(pos)CD19(pos) B precursors and express RAG-1 and TDT. These cells correspond to TEL/AML1(pos) ALL (1/4 pediatric B-precursor ALL). The development follows to CD27/CD44 double-positive (27/44DP) stage, 44SP stage and CD27/CD44 double-negative (27/44DN) stage. Before exit to periphery, CD44 is reexpressed. The 27/44DP cells are mostly large and profoundly suppress RAG-1. Despite their presumably high proliferation potential, 27/44DP cells rarely dominate in leukemia. At 44SP stage, which corresponds to TEL/AML1(neg) leukemias, RAG-1 is reexpressed and Ig light chain gene starts to be rearranged.     

Impact of cellular CD71 (transferrin receptor 1) expression in Egyptian acute leukemia: correlation with clinicopathologic features

Cellular transferrin receptor 1 (CD71) has been identified as a proliferation marker. Inferior outcome with higher expression was observed in many solid tumors. This study objected to assess the expression of CD71 in patients with acute leukemia and to address its prognostic significance and relations to clinicopathologic features. The study included 34 acute myeloid leukemia (AML) and 64 acute lymphoblastic leukemia (ALL) newly diagnosed cases from Mansoura Oncology Center. CD71 was analyzed on blast cells by flow cytometry. CD71 expression was significantly elevated in both AML and ALL. Antigen expression apparently increased in T-ALL, while in AML there was a trend toward a gradual increase of antigen expression in relation to maturation evidence of myeloid subtypes. CD71 expression correlated positively with total leukocyte count in ALL cases and negatively with platelet count in AML cases. In ALL, higher CD71 expression was associated with higher relapse rate and was an independent prognostic factor of overall survival (HR 1.8; 95 % CI 1.2–4.1). In conclusion, CD71 is overexpressed in acute leukemia; it predicts adverse clinical outcome in ALL. In addition, CD71 antagonism could be a possible therapeutic target in acute leukemia.     

多参数流式细胞术鉴别诊断单核细胞相关性白血病的意义

目的：用多参数流式细胞术（FCM）鉴别诊断单核细胞相关性白血病（MLIL）。方法：采用CD45／SSC散点图设门多参数流式细胞术分析179例白血病细胞CD14及其它相关抗原的表达情况。结果：CD14在179例白血病中的表达，AML25．6％（30／117），CML5．9％（1／17）。CMML100％（3／3）；ALL、CLL、AUL、BAL CD14都阴性。117例AML中，AML-M4 CD14阳性占75．0％（15／20），AML-M5a 22．2％（2／9），AML-M5b 92．9％（13／14）。CD14在AML-M4／M5的阳性率无明显差异（P=0．486），而AML-M5a／M5b中有显著性差异（P〈0．001）。AML-M0、M1、M2、M6、M7中CD14全部阴性。在AML组中CD14的表达与CD117、CD34呈负相关。与CD64、HLA-DR、CD4、CD36、CD15、CD11b呈正相关。在CD45／SSC、CD71／CD33、CD15／CD11b散点图中M4／M5的粒细胞和单核细胞克隆位点明显不同。结论：CD14对单核细胞相关性白血病具有高特异性，敏感性不足；联合其它抗体不但可以区别单核细胞相关性白血病，而且可以鉴别AML-M4／M5亚型；CD45／SSC、CD71／CD33、CD15／CD11b三幅散点图有助于鉴别粒细胞和单核细胞克隆。     

CD64在急性白血病免疫分型中的意义

目的探讨CD64在急性白血病免疫分型中的意义。方法应用直接荧光标记法,经流式细胞术对116例急性髓系白血病(AML)和70例急性淋巴细胞白血病(ALL)进行免疫表型的检测。结果 AML组CD64的表达阳性率明显高于ALL组(41.4%vs 2.9%,P<0.01)。CD64在M5和M4的表达阳性率最高,分别为77.1%和55.6%。CD64的阳性表达率在M0(0)、M1(0)、M2(7.9%)明显低于M3(47.1%)、M4与M5(P<0.01)。各亚型CD64阳性病例中,M4、M5的CD64阳性细胞表达率分别为(62.5±24.7)%、(68.7±25.9)%,均明显高于M2(28.3%±5.7%)、M3(34.3%±6.3%)(P<0.01)。CD64对诊断AML的灵敏度优于CD14,其特异度优于CD117、CD33及CD13。虽然CD64诊断M4\M5的特异度较CD14稍差(82.5%vs 100%),但是灵敏度高于CD14(69.8%vs 41.5%)。结论 CD64可作为辅助诊断AML的髓系标志抗原,有助于提高M4/M5的检出率及其与其他AML亚型的鉴别诊断。     

Comprehensive flow cytometry phenotype in acute leukemia at diagnosis and at relapse

Li X, Du W, Liu W, Li X, Li H, Huang S‐A. Comprehensive flow cytometry phenotype in acute leukemia at diagnostic and at relapse. APMIS 2010; 118: 353–59. Multiparameter flow cytometry (MFC) plays a vital role in the detection of minimal residual disease (MRD) and diagnosis of relapse in acute leukemia. However, application of a limited panel of antibodies in MFC leads to high rates of false‐negative and false‐positive results. Thirteen patients with acute lymphoblastic leukemia (ALL) and 12 patients with acute myeloid leukemia (AML) were immunophenotyped by MFC at diagnosis and at relapse using a comprehensive panel of monoclonal antibodies (McAbs) to 27 antigens and CD45/SSC gating. In 23 of 25 patients (92.3%), changes in at least one of progenitor‐associated, myeloid and lymphoid antigens between diagnosis and relapse were observed. Antigen changes were observed in 92 of 239 antigens (38.5%) expressed in 25 patients, in 49 of 117 antigens (41.9%) expressed in 13 ALL patients, and in 43 of 122 antigens (35.2%) expressed in 12 AML patients. Phenotypic changes were characterized by the expression of cross‐lineage antigens. The intralineage change was observed in the majority of patients. However, myeloid lineage shift was identified by MFC in two patients with T‐ALL. Multiple panels of three or more McAbs are likely to be required in the monitoring of MRD and diagnosis of relapse in acute leukemia by MFC.     

CD117在急性白血病中的表达及临床意义

目的探讨CD117在急性白血病中的表达及其临床意义。方法应用CD45/SSC设门,直接荧光标记法,经流式细胞术对73例急性髓系白血病（AML）和47例急性淋巴细胞白血病（ALL）进行CD117的检测。结果对照组、ALL及AML3组CD117的表达阳性率差异有统计学意义（χ2=41.681,P﹤0.01）。AML组CD117的表达阳性率（58.9%）明显高于对照组（0）及ALL组（8.5%）。CD117/CD34的共表达率ALL组明显低于AML组（4.3%vs45.2%,P﹤0.05）。AML组CD117＋患者的CR率为60.5%,CD117-患者为76.7%,两者比较差异无统计学意义（P〉0.05）;而CD117＋/CD34＋患者的CR率为54.5%,明显低于CD117-/CD34-患者的CR率（88.2%,P﹤0.05）。结论 CD117可作为辅助诊断AML的髓系标志抗原,CD34＋/CD117＋可作为进一步排除ALL的指标。CD117＋/CD34＋可能是AML中一类预后不良的特殊亚型,可以作为AML预后判断的指标之一。     

流式细胞术在我院急性白血病免疫分型中的应用

目的探讨本实验室所用13种单抗对白血病免疫分型的应用价值。方法应用流式细胞术（FCM）使用13种单抗对99例急性白血病进行免疫分型,与形态学分型相比较。结果使用13种单抗从99例急性白血病中分出髓系白血病（AML）59例、淋系白血病（ALL）27例、混合型（MAL）5例、未分化型（AUL）2例,诊断率达93.9%（93/99）。AML中各抗原表达情况：CD13〉CD33〉CD14、CD7〉CD2、CD19〉CD10〉CD5〉CD20,其中多表达CD13、CD33;ALL中各抗原表达情况：CD19〉CD13〉CD10〉CD20〉CD33〉CD5〉CD7〉CD2、CD14,其中CD10、CD13、CD19、CD20表达率较高。免疫分型与形态学分型结果相比较,AML二者的吻合率为90.5%（57/63）、ALL二者的吻合率为76.5%（26/34）;其中1例M0免疫分型为B/M混合、1例M1免疫分型为T/M混合、1例M2a免疫分型为T/M混合、1例L1免疫分型为B/M混合、1例L2免疫分型为T/B混合、1例L2免疫分型为Ly＋-AML、2例L2免疫分型为AUL;1例形态学为浆细胞白血病的免疫分型为AML、1例淋单混合型白血病CD7、CD13、CD14阳性。结论白血病细胞、免疫分型各具特征,形态学相同的白血病免疫分型未必相同,形态学不同的白血病免疫分型未必不同;本实验室所选单抗组合基本能满足白血病的免疫分型,对于一些混合型和未分化型白血病的诊断亦能明确。     

The immunophenotype of 325 adult acute leukemias: relationship to morphologic and molecular classification and proposal for a minimal screening program highly predictive for lineage discrimination

Bone marrow cells of 325 adults with acute leukemia were immunophenotyped using a panel of monoclonal antibodies proposed by the European Group for the Immunological Characterization of Leukemias (EGIL). Of these, 97.2% could be assigned clearly to myeloid or lymphoid lineage (254 acute myeloid leukemias [AMLs], 48 B-cell lineage acute lymphoblastic leukemias [ALLs], 14 T-cell lineage ALLs), 1.8% as biphenotypic, and less than 1% as undifferentiated. Immunologic subtyping of ALLs revealed an association between early precursor phenotypes and coexpression of myeloid antigens, particularly CD15/CD65s coexpression and pre-pre-B cell-specific phenotypes and genotypes. The common ALL phenotype was associated with BCR-ABL translocation. Among AMLs, CD2 coexpression was almost exclusively restricted to French-American-British subtypes M3 variant and M4Eo and related molecular aberrations. The most valuable markers to differentiate between myeloperoxidase-negative AML subtypes M0 and ALLs were CD13, CD33, and CD117, typical of M0, and intracytoplasmic CD79a, intracytoplasmic CD3, CD10, and CD2, typical of B cell- or T cell-lineage ALL. Our results confirm excellent practicability of the EGIL proposalfor immunologic classification of acute leukemias. For myeloperoxidase-negative AMLs, we suggest a scoring system based on markers most valuable to distinguish between AML-M0 and ALLs.     

CD80，CD86和ICAM-1在急性白血病细胞上的表达及意义

目的通过流式细胞术检测初诊患者急性自血病细胞上共刺激分子CD80、CD86以及黏附分子ICAM．1的表达，以了解其表达规律。方法通过流式细胞仪检测60例初治急性白血患者白血病细胞上CD80、CD86和ICAM-1的表达率；男37例，女23例，年龄2～85岁，中位年龄28岁；其中ALL20例，AML40例（M16例、M27例、M37例、M415例、M55例）。结果ALL组中的CD86的表达为（32．880±6．665）％，显著高于正常对照（P〈0．01），而CD80与正常BM对照比较无统计学意义；CD80、CD86在AML（M1、M2和M3）细胞上的表达分别为（0．766±0．187）％、（27．210±7．581）％，均显著高于相应的正常骨髓对照（P〈0．01）；在AML（M4和M5）细胞上CD80、CD86的表达与正常对照比较均无统计学意义。ICAM-1在ALL组中的表达与正常BM对照比较无统计学意义；在AML（M1、M2和M3）细胞上（63．820±7．484）％，显著高于相应的正常骨髓对照（P〈0．01）：而AML（M4和M5）细胞上表达为（50．590±7．092）％，显著低于相应的正常骨髓对照（P〈0．01）。结论CD80、CD86和ICAM．1在初治ALL和AML白血病细胞上的表达呈一定变异性，CD86在ALL上呈高表达，CD80、CD86和ICAM-1在AML（M1、M2和M3）上均呈高表达，而ICAM-1在AML（M4和M5）上均呈低表达。     

Transient myeloproliferative disorder and acute myeloid leukemia in Down syndrome. An immunophenotypic analysis

Immunophenotypic analysis of transient myeloproliferative disorder (TMD) and acute myeloid leukemia (AML) using multiparameter flow cytometry might provide insight into their relationship. We retrospectively analyzed the expression of multiple lymphoid, myelomonocytic, and megakaryocytic antigens on blast proliferations in 18 patients with Down syndrome (DS; AML, 9; TMD, 9). The AMLs and TMDs shared several immunophenotypic characteristics. Blasts in all expressed CD45, CD38, and CD33; most AMLs and all TMDs were CD36+; and the majority expressed CD41 and CD61, suggesting megakaryocytic differentiation. The majority of cases were CD34+, CD14-, and CD64-. There was aberrant expression of the T-cell-associated antigen CD7 in most AMLs and TMDs. CD56 was expressed aberrantly in 5 AMLs and 7 TMDs. The major difference between the disorders was the pattern of expression of myeloid markers CD11b and CD13; each was expressed in 8 AMLs but only 2 TMDs. Blasts were HLA-DR-positive in 3 AMLs vs 7 TMDs. Blasts in TMD and AML in DS have a characteristic immunophenotype distinct from AML in other settings. The immunophenotypic similarities suggest a biologic relationship between the disorders; however, distinct immunophenotypic differences also were observed.     

The value of immunohistochemistry for CD14, CD123, CD33, myeloperoxidase and CD68R in the diagnosis of acute and chronic myelomonocytic leukaemias

Rollins‐Raval M A & Roth C G
(2012) Histopathology  60, 933–942 The value of immunohistochemistry for CD14, CD123, CD33, myeloperoxidase and CD68R in the diagnosis of acute and chronic myelomonocytic leukaemias Aims: In the absence of adequate aspirate films and touch imprints, distinction of chronic myelomonocytic leukaemia (CMML) from acute myeloid leukaemia with monocytic differentiation (Mo‐AML) may be difficult solely on the basis of bone marrow biopsy morphological features. The aim of this study was to evaluate the diagnostic utility of a novel immunohistochemical panel for the diagnosis of acute and chronic myelomonocytic leukaemias in bone marrow biopsies. Methods and results: Immunohistochemical labelling for CD14, CD123, CD33, myeloperoxidase (MPO) and CD68R was assessed in 49 myeloid neoplasms with monocytic differentiation (24 CMMLs and 25 Mo‐AMLs) and compared with that of 15 non‐monocytic acute myeloid leukaemias (NM‐AMLs) and 17 non‐neoplastic controls. More than 20% CD14 immunohistochemistry (IHC)+ cells were seen only in Mo‐AMLs and CMMLs, although Mo‐AMLs showed wide variability and overlapped with other categories. More than 20% CD68R IHC+ cells had the highest sensitivity and specificity for Mo‐AML. Discrepant MPO–/CD33+ expression was specific for Mo‐AML but insensitive. A subset of blasts in Mo‐AMLs and NM‐AMLs were weakly CD123+. Conclusions: A significantly increased number of CD14+ cells raises the possibility of a myelomonocytic neoplasm but does not distinguish between CMML and Mo‐AML. Significantly increased numbers of CD68R IHC+ cells and a discrepant MPO–/CD33+ staining pattern are specific for Mo‐AML but are best utilized in a comprehensive panel.     

Benign hematogone-rich lymphoid proliferations can be distinguished from B-lineage acute lymphoblastic leukemia by integration of morphology, immunophenotype, adhesion molecule expression, and architectural features

Distinction of normal B-lymphoid proliferations including precursors known as hematogones from acute lymphoblastic leukemia (ALL) is critical for disease management. We present a multiparameter assessment of 27 bone marrow samples containing at least 25% hematogones (range, 25%-72%) by morphologic review. We used flow cytometry to evaluate B-cell differentiation antigen and adhesion molecule expression and immunohistochemistry on clot sections to evaluate architectural distribution. Flow cytometry revealed that intermediately differentiated cells (CD19+, CD10+) predominated, followed in frequency by CD20+, surface immunoglobulin-positive cells, with CD34+, terminal deoxynucleotidyl transferase (TdT)-positive cells as the smallest subset. Adhesion molecules (CD44, CD54) were expressed more heterogeneously compared with expression in acute lymphoblastic leukemia. Immunohistochemistry revealed that CD34+, TdT-positive cells were dispersed without significant clustering, while CD20+ cells exceeded CD34/TdT-positive cells in 24 of 25 cases. This multidisciplinary study demonstrates that hematogone-rich lymphoid proliferations exhibit a spectrum of B-lymphoid differentiation antigen expression with predominance of intermediate and mature B-lineage cells, heterogeneity of adhesion molecule expression, and nonclustered bone marrow architectural distribution.     

CD79 alpha expression in acute myeloid leukemia. High frequency of expression in acute promyelocytic leukemia.

CD79 alpha is a subunit of an intracytoplasmic protein reported to be specific for B lymphocytes, including immature B lineage cells. To evaluate expression of the CD79 alpha antigen in acute myeloid leukemia (AML), we studied forty-eight cases of AML by paraffin section immunohistochemistry. The cases included four MO, nine M1, nine M2, ten M3, ten M4, and six M5 AMLs using criteria of the French-American-British cooperative group. Eleven cases demonstrated cytoplasmic staining for the CD79 alpha antigen, including one M1, nine M3, and one M5 AML. These CD79 alpha-positive cases represented 5% of all non-promyelocytic AMLs and 90% of all acute promyelocytic leukemias studied. All acute promyelocytic leukemias had the characteristic t(15;17)(q24;q21), including two cases of the microgranular variant (M3v). No other B-lineage-associated antigens were found in the CD79 alpha-positive cases, with the exception of a subpopulation of CD19-positive leukemic cells in one patient. The two non-promyelocytic leukemias that expressed CD79 alpha had no evidence of t(15;17) and did not express any additional B-lineage-associated antigens that might suggest a mixed lineage proliferation. This study demonstrates that CD79 alpha expression in acute leukemia is not restricted to B-lineage acute lymphoblastic leukemias and that CD79 alpha expression is frequently associated with t(15;17) acute myeloid leukemia.     

Two cases of acute lymphoblastic leukemia with cytoplasmic granules

The presence of cytoplasmic granules in blastoid cells of patients with acute leukemia is generally accepted as a useful morphological marker for differentiation of myeloid leukemia from lymphoblastic leukemia. We diagnosed two cases of acute lymphoblastic leukemia(ALL) with cytoplasmic granulation. Surface marker analysis of leukemic cells revealed they were positive for CD10, 19, 20, 33, 34 and HLA-DR. Immunoglobulin gene rearrangement was detected by means of Southern hybridization with an Ig-JH probe for both patients. On the basis of these findings, the patients were diagnosed as having B-precursor ALL. Electron microscopic observation showed no myeloperoxidase activity, so that the granules were considered to be related to autophagolysosomes. This experience demonstrates that the recognition of the presence of granular ALL is necessary for making an accurate differential diagnosis of acute leukemias.     

Epithelial membrane antigen (EMA) or MUC1 expression in monocytes and monoblasts

AIMS: Epithelial membrane antigen (EMA) or MUC1 belongs to a heterogeneous group of heavily glycosylated proteins and is expressed in most normal and epithelial neoplastic cells. EMA is also expressed in plasma cells, anaplastic large cell lymphoma (Ki-1 antigen), malignant histiocytosis and erythroleukaemia. In 1996, Cheong et al. (Hematology 1996; 1: 223) demonstrated the positive expression of EMA in monoblasts. Since there were very few useful markers for differentiating subtypes of acute myeloid leukaemia with a monocytic component from the those without, a study was conducted to evaluate the prevalence of EMA expression and its relationship with known markers for monocytic-macrophage lineage (CD11c, CD14 and intracellular CD68) in monocytes and monoblasts. METHODS: EMA detection was performed by flow cytometry in monocytes and monoblasts. EMA expression was compared with other known markers of monocytic-macrophage lineage (CD11c, CD14 and intracellular CD68). Samples of purified monocytes were obtained from 20 healthy volunteers. Twenty-two cases of monocytic AML (M4 and M5) were studied and controls were selected from 20 cases of acute lymphoblastic leukaemia (ALL) and 18 cases of non-monocytic AML (M0, M1, M2, M3, and M7). RESULTS: EMA was shown to be expressed strongly on the surface of all purified monocytes. EMA expression was observed on blast cells in 18/22 (81.8%) cases of AML M4 and M5, but not in that of non-monocytic AML or ALL. In this study EMA monoclonal antibody has demonstrated a strong association (P<0.001) with all the other known markers of monocytic-macrophage lineage in acute leukaemia subtypes. EMA had also shown 100% specificity and 81.8% sensitivity in the diagnosis of AML M4 and M5. CONCLUSIONS: The monoclonal antibody EMA (clone E29) is a useful marker in the classification of acute myeloid leukaemia and can be used as a supplementary analysis for the diagnosis of acute leukemia with monocytic involvement.     

Immunophenotyping of acute lymphoblastic leukemia in pediatric patients by three-color flow cytometric analysis.

Immunophenotyping of acute lymphoblastic leukemia (ALL) in children using three-color flow cytometry was carried out at Chulalongkorn Hospital, Bangkok, Thailand. Of 38 patients with acute lymphoblastic leukemia, 65.8% were identified as common ALL, 15.8% were B-ALL, and 18.4% were T-ALL. Of these 38 cases, there were 4 cases of infantile leukemia. Relapsed cases of leukemia were found most in B-ALL up to 3 out of 6 cases and to a lesser extent in T-ALL (1 of 7 cases) and c-ALL (1 of 25 cases). Our data showed the CD markers expression for common ALL (c-ALL) were CD19+/10+ (100%), CD20+ (24%), CD22+ (100%), HLA-DR+ (70.1%), and CD34+ (58.8%). CD markers expression for B-ALL were CD19+ (100%), CD20+ (33.3%), CD22+ (80%), and HLA-DR+ (80%). CD markers expression for T-ALL were CD3+ (42.9%), CD5+ (100%), CD7+ (85.7%). Myeloid aberrant expressions were found in c-ALL (25-37.5%), B-ALL (20%), and T-ALL (14.3%). The significance of the aberration is discussed. The immunophenotyping classification of ALL as c-ALL, B-ALL, and T-ALL is useful in prognosis and treatment.     

Podocalyxin: a marker of blasts in acute leukemia

Podocalyxin is a CD34 family member expressed by podocytes, vascular endothelium, mesothelium, and a subset of hematopoietic progenitors. Podocalyxin expression was not observed in the hematopoietic cells of normal adult bone marrow samples. However, podocalyxin was expressed by blasts in 30 (77%) of 39 cases of acute myeloid leukemia (AML), 22 (81%) of 27 cases of acute lymphoblastic leukemia (ALL), and 13 (87%) of 15 cases of cutaneous myeloid sarcoma. No correlation with CD34 expression by immunohistochemical analysis was seen. Wilms tumor 1 (WT1) expression was detected in blasts in 17 AML cases (44%) and 21 ALL cases (78%). There was no correlation between WT1 and podocalyxin expression. We conclude that podocalyxin is expressed commonly by blasts in ALL and AML. Analysis of the expression of CD34 and podocalyxin increases sensitivity for the immunophenotypic detection of leukemic blasts compared with the analysis of CD34 alone. Therefore, podocalyxin seems to complement CD34 as a useful hematopoietic blast marker. The physiologic role of podocalyxin in leukemic blasts remains unknown.