Novel T-cell receptor δ gene rearrangement involving a recombining element located 2.6 kb 3′ from the Vδ2 gene segment

In this study, we describe a novel T-cell receptor δ (TCRδ) gene rearrangement observed in acute myeloid leukemia with coexpression of T-lymphoid antigens (Ly+AML) and in peripheral blood leukocytes (PBL) from one out of ten healthy donors. The rearrangement was identified by Southern blot analysis using a joining region (Jδ1) specific probe and amplified by polymerase chain reaction (PCR) with a variable region (Vδ2) and Jδ1 specific primers. The nucleotide sequence analysis of an atypical 3000 bp PCR product allowed localization of the breakpoint within the TCRδ gene locus, 2.6 kb 3′ from the Vδ2 gene segment. A regular Dδ2–Dδ3–Jδ1 joining was found at the 3′ end of the breakpoint, indicating that the rearrangement was mediated by the VDJ recombinase, but no TCRδ gene segment was detected at the 5′ end. Analysis of the germline sequence 3′ from the breakpoint revealed an isolated recombination signal sequence (RSS) capable of initiating a rearrangement. The RSS motif described by us is the second TCRδ recombining element (δRec2). The δRec2(Dδ)Jδ1 recombination is a rather rare event and can be found in acute leukemia and in PBL from healthy individuals. Most likely, the nonfunctional δRec2(Dδ)Jδ1 rearrangement is a transient step during the VDJ recombination. It may potentially lead to deletion of the δRec2(Dδ)Jδ1 complex and either to direct joining of a Vδ region to one of the downstream Jδ regions or to a rearrangement of the TCR gene.     

Heterogeneity of V52 TCR 8 Gene Rearrangements in Acute Myeloid Leukemia

In a previous study, we described the occurrence of T-cell receptor (TCR)δ gene rearrangements in 9/100 acute myeloid leukemia (AML) cases. In this study, we further characterized these rearrangements by Southern Blot hybridization using a Vδ2 specific probe and polymerase chain reaction (PCR). Southern Blot analysis revealed that rearrangements involved the Vδ2 gene segment in four patients. Interestingly the restriction fragments detected by the Vδ2 probe differed markedly in size. PCR analysis revealed a complete Vδ2(Dn)Jδ1 gene rearrangement, an incomplete Vδ2Dδ3 rearrangement and a large amplification product, which cannot be explained with normal VDJ recombinatorial processes, in one case each. Furthermore although Vδ2 and Jδ1 were rearranged, no comigration of rearranged fragments was observed and no PCR product was obtained in one case.

Obtained results in AML differ from findings in acute lymphoblastic leukemia (ALL) of B-cell lineage, where a more homogeneous pattern of rearrangements has been described. This heterogeneity might be related to the illegitimate occurrence of TCRδ gene rearrangements in AML.     

Prognostic Significance of Immunoglobulin and T Cell Receptor Gene Rearrangements in Patients with Acute Myeloid Leukemia: Taiwan Experience

We investigated the prognostic significance of lymphoid antigen receptor gene rearrangement in patients with newly diagnosed acute myeloid leukemia (AML). Thirty-nine patients were included in the study. Clonal gene rearrangement of immunoglobulin heavy chain (IgH) and T cell receptor β chain (TCRβ) was found in leukemic cells in 11 (28.2%) and 10 (25.6%) patients, respectively. Five (12.8%) had both IgH and TCRβ gene rearrangements. Three of the seven (42.9%) B-lymphoid marker-positive and eight of the 32 (25%) B-lymphoid marker-negative patients had clonal IgH gene rearrangements. Five of the 11 (45.5%) T-lym-phoid marker-positive and 5 of the 28 (17.9%) T-lymphoid marker-negative patients had clonal TCRβ gene rearrangements. All patients were treated with similar regimens. The complete remission rate (62.5% vs 65.296, p=1.000) and median survival (13 vs 14 months, p=4.366) were similar in patients with and without clonal IgH or TCRβ gene rearrangements. In conclusion, while clonal rearrangements of IgH or TCRβ genes were found in AML patients, they did not appear to effect the prognosis.     

Rearrangements of T-cell receptor delta, gamma and beta genes in acute myeloid leukemia coexpressing T-lymphoid features.

In order to investigate the role of T-cell receptor (TcR)-delta and TcR-gamma gene rearrangements and/or deletions in acute myeloid leukemia (AML) coexpressing T-cell-associated antigens (i.e. CD2 and/or CD4 and/or CD7), we examined blasts from a selected group of 56 AML cases (25 children, 31 adults) coexpressing either of these antigens without cytoplasmic CD3 expression. Forty-four typical AML cases (7 children, 37 adults) without T-cell associated antigens were further studied as controls. Germline configuration of the TcR-delta gene was observed in 91 out of the total of 100 AML cases investigated. Eight of nine cases with rearranged or deleted TcR-delta genes coexpressed T-cell-associated antigens. Blast cells of 7/9 cases were classified as FAB M1, two as FAB M2. In six of these cases TcR-gamma gene rearrangements were also detected. TcR-delta alterations were predominantly found in children whose blasts coexpressed T-lymphoid associated antigens (6/25, 24%), but were rarely detected in adult AML with or without coexpression of T-cell antigens (2/31 and 0/37, respectively).     

Lack of correlation between immunoglobulin and T cell receptor gene rearrangements and TdT expression in acute myeloid leukaemia.

Thirty-two cases of acute myeloid leukaemia (AML) were examined for expression of terminal deoxynucleotidyl transferase (TdT) and rearrangements of the genes coding for the immunoglobulin heavy chain and the beta chain of the T cell receptor, in order to establish whether these two forms of lineage infidelity are linked. In 17 cases of AML with greater than or equal to 10% TdT+ cells, three cases showed evidence of gene rearrangement, two having clonal rearrangements in the immunoglobulin gene and one with a rearranged T cell receptor gene. Among 15 AML cases without significant numbers of TdT-positive blasts, three cases had rearrangements in both immunoglobulin and T cell receptor genes, while a fourth case had an immunoglobulin gene rearrangement. No relationship was seen between lymphoid gene rearrangements and expression of the lymphoid surface antigens CD7 and CD10. The lack of association between TdT expression and gene rearrangements does not support the concept of an orderly activation of the recombinase machinery in those cases of AML with features of early lymphoid differentiation.     

Incidence of lineage promiscuity in acute myeloblastic leukemia: diagnostic implications of immunoglobulin and T-cell receptor gene rearrangement analysis and immunological phenotyping

Sixty-nine blood or bone marrow samples from both children and adults with acute myeloblastic leukemia (AML) were investigated to elucidate the frequency of immunoglobulin (IG) and T-cell receptor (TCR)-gene rearrangements. Non-germline configuration for the IG heavy chain (h) gene was detected in the specimens of nine patients of various subtypes according to the French-American-British classification (FAB), including FAB M1, M2, M4 and M5. Rearrangement of the IG kappa chain (k) gene was present in one of these cases which simultaneously revealed a rearranged TCR-beta (b) chain gene. In another two AML samples we found TCR-b gene rearrangements, in one case in combination with an IG-h gene rearrangement. IG-h gene rearrangements were detected in 10 cases, in one case in conjunction with an IG-kappa (k) and TCR-b gene rearrangement. A highly significant correlation between the occurrence of DNA rearrangements of the IG-h locus and nuclear staining with the enzyme terminal deoxynucleotidyl transferase (TdT) and surface expression of the CD 19 and CD 34 antigen could be identified: all 10 TdT positive AML samples rearranged IG-h. Similarly, six out of 69 AML samples exhibited surface expression of CD 19, five of these in combination with CD 34 and all of them rearranged the IG-h gene. The one leukemia with TCR-b gene rearrangement only was TdT positive as well, but did not express CD 19 or CD 34. We conclude that IG-h gene is rearranged in a substantial proportion of AML, strongly associated with a specific immunophenotype (TdT+, CD19+, CD34+), whereas TCR-b gene rearrangement appears more rarely. No positive correlation between occurrence of IG-h and TCR-b gene-rearrangements and one AML FAB-subtype was found, although a clustering of M1 and M4 FAB subtypes in the AML group showing reconstructed IG-h gene became evident.     

Characterization of Philadelphia-chromosome-positive acute leukemia by clinical, immunocytochemical, and gene analysis.

Philadelphia chromosome (Ph') was detected at presentation in 10 out of 110 patients with acute lymphoblastic leukemia (ALL) and five of 168 patients with acute myelogenous leukemia (AML). Two other ALL patients who had studies at relapse were also included in the analyses. One of the 12 Ph'-positive (Ph+) ALL patients had simultaneous expression of myeloid-associated antigen on the leukemic blasts, while all the five AML patients coexpressed markers of lymphoid cells. Double labeling of the cells with myeloperoxidase and CD10 on three Ph+ AML cases showed that most leukemic blasts expressed either myeloperoxidase activity or CD10 but not both. Cross-lineage gene rearrangements of T-cell receptor (TCR) beta-chain gene were detected in three of the eight Ph+ ALL patients tested. All the four Ph+ AML cases studied showed immunoglobulin heavy chain gene rearrangements, and three of them also had simultaneous rearrangements of TCR beta-chain gene. The results revealed that Ph+ acute leukemia in this study belonged either to ALL or mixed lineage leukemia, and none was pure AML. This finding is contrary to that of acute blast crisis of chronic myelogenous leukemia in which the majority of patients had myeloid transformation. Rearrangements of bcr were detected in four of the 10 Ph+ ALL and three of the four Ph+ AML patients tested. No significant difference was noted in the clinical or hematologic manifestations among Ph+ leukemia with or without bcr rearrangements.     

Surface marker analysis and karyotype distinguish acute biphenotypic leukemia from acute myelogenous leukemia expressing terminal deoxynucleotidyl transferase

Surface phenotyping by flow cytometry and cytochemical study were used to identify 15 adult patients with acute leukemia displaying ambiguous phenotypes. Differences were found in the blast cell karyotype and immunoglobulin gene rearrangements of terminal deoxynucleotidyl transferase (TdT)-positive acute myelogenous leukemia (AML) and biphenotypic leukemia expressing B lymphoid and myeloid markers. The karyotypic abnormalities, t(9;22) and t(4;11), were noticed in acute biphenotypic leukemia, and were consistently associated with rearrangement at the immunoglobulin locus. Furthermore, coexpression of CD19/CD20 and either myeloperoxidase or myeloid surface markers were predictive of finding the t(9;22) or t(4;11) karyotype. Patients with TdT-positive AML, on the other hand, were less likely to show rearrangement at the immunoglobulin locus, and did not have the t(9;22) or t(4;11). Instead, a variety of nonrandom karyotypic abnormalities were seen, including trisomy 13. Unlike common AML, the majority of TdT-positive cases demonstrated an abnormal karyotype with duplications and/or deletions present in all cases. In no instance was trisomy 8, t(8;21), t(15;17), or any other isolated translocation identified. The authors therefore suggest that immunophenotyping, when combined with cytochemical analysis of TdT and myeloperoxidase or Sudan black B, may aid in the characterization of subgroups of atypical acute leukemia, such that alternate approaches to therapy can be evaluated.     

急性髓系白血病细胞表面同时表现淋系抗原的临床及免疫学分析

目的 探讨淋系抗原在急性髓系白血病细胞上的表达及意义。方法 采用间接免疫荧光法检测182例急性髓系白血病细胞的免疫表型。根据FAB亚型和免疫标志将病例分为2组：伴淋系相关抗原的急性髓细胞性白血病(Ly^ AML),不伴淋系相关抗原的急性髓细胞性白血病(Ly^-AML)。结果 182例AML中有64例表达淋系抗原(33％), CD7^ 在AML中表达率为54．7％,M0中阳性率最高100％,M1次之78％。Ly^ AML组的白细胞、血小板数高于Ly^-AML,有显著性差异。Ly^ AML,组与Ly^-AML组的诱导缓解率及临床特征无显著性差异。Ly^ AML组和Ly^-AML组比较,平均缓解期较短。结论 CD7^ AML与AML-M0、M1有着密切的关系。可以看作是一个独特的临床亚型。Ly^ AML较之Ly^-AML,具有不同的临床特征和短CR期。Ly^ AML的出现可以作为危险因子中的一个因子来选择更合适的化疗也许是必要的。     

Rearrangement of immunoglobulin and T cell antigen receptor genes in acute myeloid leukemia with lymphoid-associated markers

Ten cases of adult acute myeloid leukemia (AML) displaying lymphoid-associated markers CD7 and/or terminal deoxynucleotidyl transferase (TdT) have been investigated for rearrangement of immunoglobulin and T cell antigen receptor beta and gamma genes. Two of six TdT+ cases had clonally rearranged Ig genes, whereas six of eight CD7+ AMLs, including three that were TdT+, had a germ line configuration of both immunoglobulin and T cell receptor beta and gamma genes. A single case of CD7+ TdT- AML had clonal rearrangement of all three genes. These results indicate that expression of TdT and/or CD7 is not accompanied by gene rearrangement in most cases of adult AML. A minority of cases, displaying lymphoid-associated phenotypic markers and accompanying gene rearrangement, may represent a distinct subgroup of AML that arises from a rare, primitive stem cell, possessing extensive multilineage potential.     

Detection of acute leukemia cells with mixed lineage leukemia (MLL) gene rearrangements by flow cytometry using monoclonal antibody 7.1.

Translocations involving 11q23 are among the most common genetic abnormalities in hematologic malignancies, occurring in approximately 5-10% of acute lymphoblastic leukemia (ALL) and 5% of acute myeloblastic leukemia (AML). In 11q23 translocations, the mixed lineage leukemia (MLL) gene on chromosome 11, band q23, is usually disrupted. The human homologue of the rat NG2 chondroitin sulfate proteoglycan molecule, as detected by the monoclonal antibody (moab) 7.1, was shown to be expressed on leukemic cells with MLL rearrangements of children with acute leukemia. We further investigated the reactivity of the moab 7.1 on 533 cell samples of adults (n = 215) and children (n = 318) with acute leukemias (271 AML, 217 B-lineage ALL, 37 T-lineage ALL, eight CD7+ CD56+ myeloid/natural killer cell precursor acute leukemias) by flow cytometry. In AML, 38 samples were positive for moab 7.1 ('20%-cut-off-level'). These moab 7.1-positive AML cases revealed a myelomonocytic-differentiated immunophenotype with coexpression of the NK cell marker CD56 in 33 of 38 cases. Two of eight cell samples of the recently described CD7+ CD56+ myeloid/natural killer cell precursor acute leukemia entity reacted with moab 7.1. In ALL, 35 samples mostly of the pro-B-ALL subtype (33 pro-B-ALL, one common-ALL, one pre-B-ALL) were positive for moab 7.1. 58 (81%) of 72 samples with MLL rearrangements were positive for moab 7.1 including 28/31 with a t(4;11), 16/17 with a t(9;11), 3/5 with a t(11;19), and 2/6 with a del(11)(q23). All moab 7.1-positive ALL (n = 34) and childhood AML (n = 17) cases revealed MLL rearrangements as detected by Southern blot analysis and RT-PCR. However, 11 adults with AML, and one adult with moab 7.1-positive CD7+ CD56+ myeloid/natural killer cell precursor acute leukemia were negative for MLL rearrangements as proved by Southern blot analysis. We conclude that moab 7.1 is a sensitive but not entirely specific marker for the identification of 11q23-associated AML and ALL by flow cytometry in children and adults.     

Multiparameter analysis of acute mixed lineage leukemia: correlation of a B/myeloid immunophenotype and immunoglobulin and T-cell receptor gene rearrangements with the presence of the Philadelphia chromosome translocation in acute leukemias with myeloid morphology

Morphological, immunological, cytogenetic, and molecular features of 28 cases of acute mixed lineage leukemia (AMLL), defined by the co-expression of lymphoid and myeloid cell surface antigens, were correlated in a multiparameter study. These 28 cases were identified in a series of 260 consecutive acute leukemia cases occurring predominantly in adults and were subdivided into 18 cases of AMLL with myeloid morphology and cytochemistry (AMLL-AML) and 10 cases of AMLL with lymphoid morphology and cytochemistry (AMLL-ALL). A lack of correlation was observed between the expression of B- or T-cell associated antigens with the presence of the expected immunoglobulin (Ig) or T-cell receptor (TCR) gene rearrangements in the AMLL cases with myeloid morphology. Only three of the 18 total AMLL-AML cases, each co-expressing B- and myeloid-associated cell surface antigens (B/My), had Ig heavy chain gene rearrangements with or without rearrangements of TCR genes. Ig light chain genes remained in the germline configuration. Strikingly, these three cases were the only AMLL-AML cases in our series to have the Philadelphia (Ph) chromosome translocation t(9;22)(q34;q11), suggesting that a significant percentage of acute leukemias with myeloid morphology and gene rearrangements may be Ph+ AMLL. The fact that three of the 10 B/My AMLL-AML cases in our series were Ph+ suggests that there may be an increased frequency of Ph chromosome, a translocation associated with a poor prognostic outcome, in B/My AMLL-AML occurring in the adult population. Although most AMLL cases with lymphoid morphology had Ig and TCR gene rearrangements associated with a variety of immunophenotypes and karyotypes, two Ph+ AMLL-ALL cases had many similar features (B/My immunophenotype; IgH with or without TCR rearrangements; Ig light chain genes germline) to their Ph+ AMLL-AML counterparts. However, the Ph+ AMLL-ALL cases differed from the Ph+ AMLL-AML cases by the expression of a more mature B-cell lineage immunophenotype and by their additional cytogenetic changes.     

Clinical Significance of Co-expression of Aberrant Antigens in Acute Leukemia: A Retrospective Cohort Study in Makah Al Mukaramah,Saudi Arabia

Background: Aberrant phenotypes in acute leukemia have variable frequency and their prognostic andpredictive relevance is controversial, despite several reports of clinical significance. Aims: To determinethe prevalence of aberrant antigen expression in acute leukemia, assess clinical relevance and demonstrateimmunophenotype-karyotype correlations. Materials and Methods: A total of 73 (40 AML and 33 ALL) newlydiagnosed acute leukemia cases presenting to KAMC, Kingdom of Saudi Arabia, were included. Diagnosis wasbased on WHO criteria and FAB classification. Immunophenotyping by flow cytometry, conventional karyotypingand fluorescence in situ hybridization for gene rearrangements were performed. Results: Aberrant antigens weredetected in 27/40 (67.5%) of AML and in 14/33 (42.4%) in ALL cases. There were statistically significant higherTLC in Ly+ AML than in Ly-AML (p=0.05) and significant higher blast count in ALL with aberrant antigensat presentation and day 14 (p=0.005, 0.046). There was no significant relation to clinical response, relapse freesurvival (RFS) or overall survival (p>0.05), but AML cases expressing ≥2 Ly antigens showed a lower medianRFS than those expressing a single Ly antigen. In AML, CD 56 was expressed in 11/40. CD7 was expressed in7/40, having a significant relation with an unfavorable cytogenetic pattern (p=0.046). CD4 was expressed in 5/40.CD19 was detected in 4/40 AML associated with M2 and t (8; 21). In ALL cases, CD33 was expressed in 7/33and CD13 in 5/33. Regarding T Ag in B-ALL CD2 was expressed in 2 cases and CD56 in 3 cases. Conclusions:Aberrant antigen expression may be associated with adverse clinical data at presentation. AML cases expressing≥2 Ly antigens may have shorter median RFS. No specific cytogenetic pattern is associated with aberrant antigenexpression but individual antigens may be related to particular cytogenetic patterns. Immunophenotype-karyotypecorrelations need larger studies for confirmation.     

成人急性髓细胞性白血病免疫表型与细胞遗传学及临床特征的关系

背景与目的:新的WHO分类已迅速应用于白血病的诊断。依据多个系相关抗原的表达,多参数高分辨流式细胞术可准确地识别白血病细胞的系列来源和分化阶段,而且某些抗原表达与细胞遗传学改变和预后密切相关。本研究旨在探讨初治成人急性髓细胞性白血病(acutemyeloidleukemia,AML)的免疫表型特征,并对其与FAB分类、细胞遗传学和临床表现的关系进行分析。方法:采用多参数高分辨流式细胞术对96例成人AML患者骨髓进行免疫表型分析,染色体G显带技术对其中的73例进行核型分析。结果:AML患者中,某些免疫表型特征与FAB分类具有相关性,包括M3中缺乏表达HLA鄄DR、CD34和CD56,但CD2的表达增加;M2中CD19、M5中CD14和CD56的表达增加,而M0中未见MPO的表达。本组AML核型异常率为54.8%,其中CD22、CD56和TdT的表达与核型异常有显著性相关。10例t(8;21)改变仅见于M2中,并高表达CD15、CD19、CD34和CD56,但未见CD2和CD7表达。7例伴t(15;17)的M3患者中未见淋系抗原的表达。此外,CD4和TdT抗原的表达与患者年龄、CD7和CD14的表达与外周血白细胞计数、CD4、CD14和CD56的表达与血小板计数等均有显著性正相关。结论:AML患者免疫表型与细胞遗传学的相关性提示AML抗原的异常表达可能与基因的异常改变密切相关。白血病免疫表型的检测有助于     

Molecular Structure of the Rearranged T-Cell Gamma Chain Gene in a Human Leukemia Which Expresses Its Product

The gamma gene product is a component of the second T-cell receptor. We report a new case of acute lymphoblastic leukemia bearing a CD3+ CD4- CD5+ CD7+ CD8- WT31- immunophenpotype that expresses the gamma peptide. Immunoprecipitation studies using an anti Cγ heteroantisera showed two different bands of 40 and 60 Kd. Southern analysis revealed Cγ1 utilization in the productive rearrangement. The demonstration of Vδ-Jδ1 rearrangement in this leukemia suggests that the 60 Kd band could correspond to the product of the delta gene. The utilization of the Jγ1.3 exon in this leukemia suggests that the T lymphocytes that undergo leukemic transformation are derived from a population different from the circulating γ/δ lymphocytes, that preferentially use the Jγ1.2 (JγP) exon.     

Immunological classification of acute myeloblastic leukemias: relevance to patient outcome.

Immunophenotyping is a major tool to assign acute leukemia blast cells to the myeloid lineage. However, because of the large heterogeneity of myeloid-related lineages, no clinically relevant immunological classification of acute myeloblastic leukemia (AML) has been devised so far. To attempt at formulating such a classification, we analyzed the pattern of expression of selected antigens, on blast cells collected at AML diagnosis. Patients were eligible if they had a first diagnosis of de novo AML and a sufficient number of blast cells for proper immunophenotyping. The relative expression of CD7, CD13, CD14, CD15, CD33, CD34, CD35, CD36, CD65, CD117, and HLA-DR were analyzed by cytometry in a test series of 176 consecutive AML cases. Statistical tools of clusterization allowed to remove antigens with overlapping distribution, leading us to propose an AML classification that was validated in a second AML cohort of 733 patients. We identified five AML subsets (MA to ME) based on the expression of seven antigens within four groups (CD13/CD33/CD117, CD7, CD35/CD36, CD15).-MA and MB-AML have exclusively myeloid features with seldom extramedullary disease and rare expression of lymphoid antigens. No cases of acute promyelocytic leukemia (APL) were observed within MB AML. MC AML have either myeloid or erythroblastic features. MD AML have more frequently high WBC counts than other subsets, which were related to the expression of CD35/CD36 and CD14 and to monoblastic differentiation. ME AML lack CD13, CD33, and CD117 but display signs of terminal myeloid differentiation. Specific independent prognostic factors were related to poor overall survival in each immunological subset: CD34+ (P<3 x 10(-4)) in MA AML, CD7+ in MB AML, non-APL cases (P<0.03) in MC AML, CD34+ (P<0.002) and CD14+ (P<0.03) in MD AML, CD14+ in ME AML (P<0.01). The inclusion of seven key markers in the immunophenotyping of AML allows a stratification into clinically relevant subsets with individual prognostic factors, which should be considered to define high-risk AML populations.     

Enhanced myeloid specificity of CD117 compared with CD13 and CD33

The c-kit proto-oncogene encodes a 145 kd tyrosine kinase transmembrane receptor, which plays a key role in haemopoiesis. The c-kit has been classified as CD117 and is especially useful in the differential diagnosis of acute myelogenous leukemia (AML) and acute lymphoblastic leukemia (ALL). We analysed 104 consecutive cases (55 AML, 23 B-cell lineage ALL, three T-cell ALL, 11 blast crisis of chronic myeloproliferative disorders and 12 cases of myelodysplastic syndromes with more than 10% of blasts) referred to our Hospital for immunophenotypic diagnosis and compared the expression pattern of CD13, CD33 and CD117 using the same fluorochrome (phycoerythrin-PE). The recommendations of the EGIL group were followed in order to establish lineage involvement of the blastic population. The threshold used to assign positivity for CD117 was 10%. Bcr/abl, TEL/AML-1 and MLL rearrangements were assessed by molecular methods. CD117 expression was detected in 91% of AML and MDS. All the negative cases corresponded to acute monocytic leukemias. The calculated specificity for myeloid involvement was 0.86 for CD117, 0.36 for CD13 and 0.44 for CD33 (P < 0.005). CD117 was also positive in four cases of ALL. None of these cases showed bcr/abl or MLL rearrangements. In the light of these findings, CD117 expression should yield a higher score, at least one point, in the system currently applied for the diagnosis of biphenotypic acute leukemias (BAL) as its myeloid specificity is greater than that of CD13 and CD33. Moreover, its absence in AML could identify two subgroups of M5b cases. The coexpression of CD117 with cytoplasmic CD79a is often associated with CD7 reactivity, suggesting a stem cell disorder. CD117 should be included on a routine basis for the immunophenotypic diagnosis of acute leukemias.     

Detailed clonality analysis of relapsing precursor B acute lymphoblastic leukemia: implications for minimal residual disease detection

Genetic instability has important implications for detection of minimal residual disease (MRD) when the target is a clonal genetic marker revealed at diagnosis. A successful MRD detection approach requires a stable marker and for lymphoid leukemias clonal rearrangements of immunoglobulin (Ig) and T cell receptor (TCR) genes are commonly used. In the present study, Ig heavy chain (IgH) and TCR (γ and δ) genes were studied in 18 consecutive, relapsing precursor-B ALL patients. At least one clonal rearrangement was found in all cases at presentation (IgH 94%, TCRγ 39% and TCRδ 28%). An altered rearrangement pattern between diagnosis and relapse was demonstrated in 14 patients (78%). At least one stable molecular target was found in 13 out of 18 cases (72%). Clonal differences between diagnostic and relapse samples were explained by: (1) loss of original rearrangements; (2) V_H to DJ_H joining; (3) V_H gene replacement; (4) appearance of new rearrangements. In two cases with apparently new IgH gene rearrangements at relapse extended sequencing of the diagnostic samples revealed minor clonal rearrangements identical to the relapse clones. Interestingly, one patient displayed instability on both the IgH and TCR gene loci, whereas a stable Igκ rearrangement was found at presentation and relapse. These data show that clonal diversity is common in precursor-B ALL and strongly suggest that MRD detection should include multiple gene targets to minimize false-negative samples. Even so, five of our 18 relapse cases (28%) lacked stable clonal markers and should have been unsuitable for MRD detection.     

成人急性髓系白血病的免疫学特点及预后

目的：探讨急性髓细胞白血病（AML）的免疫表型特点。方法：使用淋系和髓系单抗,用间接免疫荧光法对70例原发性AML进行免疫表型分析。结果：所有AML患者的细胞至少被1种髓系单抗标记,各髓系抗原的表达率依次为CD33＞CD13＞CD15。所有M3患者CD9为阳性。16／70例（30％）表达CD34抗原、CD34^ AML组在年龄、外周血象及骨髓原始、幼稚细胞比例等方面与CD34^-组相比较无显著差别,但表达CD34抗原的AML常伴有HLA－DR、CD38、CD7等不成熟细胞表面标记的表达,而较成熟的髓系细胞表面标记CD15则不表达。70例AML中有16例表达淋系抗原,CD4^ 例（13．8％,M2为8．8％,M460％）;CD7^ 9例（16．9％,M1为50％,M218％,M5b16．7％）。CD4^ 的AML患者CD34为低表达,CD33表达。结论：CD9^ 、CD34^-、HLA－DR^-及CD13^ 、CD15^ 是典型M3的免疫表型特点。CD34^ AMLgn AML-M1有着密切的关系,且对化疗反应较差,证明CD34^ 的AML是一组分化程度较差的类型;提示CD7^ 和CD4^ 的AML预后差,CD7^ 的AML的一种独特类型。