Purine metabolism in childhood acute lymphoblastic leukemia: biochemical markers for diagnosis and chemotherapy

Adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), 5'nucleotidase (5'NT), ecto-5'NT, hypoxanthine-guanine phosphoribosyltransferase(HGPRT), adenine phosphoribosyltransferase(APRT), adenosine kinase(AK), AMP deaminase (AMPD) and adenylate kinase(AdKin) activities were assayed in leukemic cells from bone marrow and/or peripheral blood of 43 newly diagnosed children with acute lymphoblastic leukemia(ALL). These enzyme activities have been investigated in relation to some immunological markers. ADA activity was higher in E-rosette positive leukemia(E+ ALL), while HGPRT, APRT, PNP, 5'NT, ecto-5'NT and AdKin activities were found to be lower in E+ ALL as compared to E- ALL. In common ALL (cALL) antigen positive leukemia, mean ADA activity was significantly lower as compared to cALL- leukemia, whereas PNP, 5'NT, ecto-5'NT and AdKin activities were significantly higher. cALL cells with cytoplasmic immunoglobulin M(IgM) heavy chains were found to have mean 5'NT activities twice as high as cALL cells lacking cytoplasmic IgM heavy chains. In two patients who had surface immunoglobulins on their cell membranes, low 5'NT activities were found. When measuring enzyme activities after 2-4 days of prednisone monotherapy, only mean ADA and HGPRT activities decreased in non-B, non-T ALL. These decreases were not significant in T-ALL patients. Mean enzyme activities in the leukemic cells of five patients with relapse were comparable to those in newly diagnosed patients, except for 5'NT, which was found to be within the activity range of control peripheral blood lymphocytes. It is concluded that ADA and AdKin activities are suitable as markers for E+ ALL and cALL+ leukemias respectively. 5'NT might help to distinguish between cALL cells having and lacking pre-B characteristics. Since 5'NT activity may also be decreased in B-ALL, it is not suitable as a T-ALL marker. Enzymes of purine metabolism in leukemic relapse need further investigation.     

Enzymological studies in chronic lymphocytic leukemia

Adenosine deaminase (ADA), 5'nucleotidase (5'NT), ecto-5'NT, purine nucleoside phosphorylase (PNP), hypoxanthine-guanine phosphoribosyltransferase (HGPRT), adenine phosphoribosyltransferase (APRT), adenosine kinase (AK), AMP-deaminase (AMPD) and adenylate kinase (AdKin) activities were assayed in peripheral blood lymphoid cells from 20 patients with B-cell type chronic lymphocytic leukemia (CLL). Significantly decreased mean activities of ADA, 5'NT, ecto-5'NT, PNP and AMPD were observed when comparing B-CLL lymphoid cells with control peripheral blood lymphocytes (PBL). AK and AdKin activities however, were found to be higher in B-CLL. Relatively wide ranges of ADA and 5'NT activity were observed. In patients with paraproteinaemia, 5'NT activity was found to be relatively high and in the range of the activities in normal PBL. ADA activity seemed to be slightly higher in patients without paraproteinaemia. No correlation could be found between the enzyme activities and the number of cells rosetting with sheep erythrocytes or bearing surface immunoglobulin (sIg). A relationship was suggested between 5'NT activity and Ig production.     

5′nucleotidase,adenosine deaminase and purine nucleoside phosphorylase activities in acute leukaemia

Three enzymes concerned in purine degradation, 5′nucleotidase (5′NT), adenosine deaminase (ADA) and purine nucleoside phosphyorylase (PNP) have been measured biochemically in the bone marrow or peripheral blood blasts from 75 patients with acute leukaemia, from 18 patients with blast crisis of chronic granulocytic leukaemia and in the bone marrow and peripheral blood lymphocytes from 14 normal donors. Characteristic patterns among the different sub-types of acute leukaemia have been detected, with high ADA, low 5′NT and PNP in Thy-ALL, high 5′NT and ADA in c-ALL, high PNP and low ADA in AML. The cells in CGL blast transformation resembled the enzymatic pattern of either AML or c-ALL respectively. However, no significant correlation was found between any pair of enzymes in any group of leukaemia, normal bone marrow or peripheral blood lymphocytes studied here.     

Overexpression of CD73 in epithelial ovarian carcinoma is associated with better prognosis, lower stage, better differentiation and lower regulatory T cell infiltration

Objective

The purpose of the current study was to evaluate survival outcome according to the expression status of CD73 in patients with epithelial ovarian cancer.

Methods

A total of 167 patients with epithelial ovarian cancer were enrolled in the current study. For each patient, a retrospective review of medical records was conducted. Immunohistochemical staining for CD73, CD8, FoxP3, and CD68 was performed using tissue microarray made with paraffin embedded tissue block.

Results

Among the enrolled patients, 29.9% of patients (n=50) showed negative expression for CD73, whereas 70.1% of patients (n=117) showed positive expression for CD73. The CD73 positive group showed better prognosis compared to the CD73 negative group (5-year overall survival of CD73 positive group, 73.0%; that of CD73 negative group, 50.1%; p=0.023). CD73 was more frequently expressed in mucinous adenocarcinoma and clear cell carcinoma compared to serous or endometrioid adenocarcinoma. In addition, CD73 overexpressions were more frequently detected in patients with known good prognostic factors, i.e., low stage, well/moderate differentiation, negative peritoneal cytology, no lymphovascular involvement, and no macroscopic residual tumor after debulking surgery. There was significantly more infiltration of regulatory T cells in the CD73 negative group compared to the CD73 positive group.

Conclusion

Good prognosis in patients with overexpression of CD73 may be due to that overexpression of CD73 was more frequently observed in epithelial ovarian cancer patients with known good prognostic factors. Therefore, this result means that favorable differentiation and stage have more influence on survival outcome than adverse effect of CD73 per se.     

5-aza-2'-deoxycytidine therapy in patients with acute leukemia inhibits DNA methylation

The effect of 5-aza-2'-deoxycytidine (5-AZA-dCyd) on methylation of DNA in blood leukemic cells from patients with lymphoid and myeloid leukemia was investigated. After treatment with continuous infusion of 5-AZA-dCyd (1.0 mg/kg/h) the blood leukemic cells were isolated and incubated in vitro with [6-3H]deoxycytidine and the incorporation of radioactivity into 5-methylcytosine and cytosine of DNA determined. 5-AZA-dCyd produced greater than 70% inhibition of DNA methylation in the leukemic cells. The antileukemic action of 5-AZA-dCyd may be related to the inhibition of DNA methylation.     

Purine degradative enzymes in circulating malignant cells of patients with chronic B cell neoplasia

Previous reports have shown that the purine degradative enzymes adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP) and ecto-5'-nucleotidase (5'NT), play an important role in the normal development of lymphocytes and that investigations of these enzymes are of value in defining subsets of lymphoid malignancies of T-cell origin. Pharmacological inhibition of one of these enzymes has been found to be an effective treatment for a few lymphatic neoplasia. We have studied the activities of the above enzymes in the circulating malignant cells of 25 patients with B-chronic lymphatic leukemia (B-CLL), four patients with B prolymphocytic leukemia (PLL), seven patients with leukemic centrocytic lymphoma (CC), 18 patients with hairy cell leukemia (HCL) and 16 patients with immunocytoma (IC). For comparison, the blasts of nine patients with 'common' acute lymphatic leukemia (cALL) and normal T (n = 12) and B (n = 8) cells were simultaneously investigated. Despite morphologic similarity, the leukemic cells of the chronic B cell malignancies demonstrate different enzyme patterns. B-CLL is characterized by very low activities of all the enzymes ADA, PNP and 5'NT. In the cells of HCL the highest values of PNP are found. The leukemic cells of IC are characterized by low levels of ADA but moderate levels of PNP and high levels of 5'NT. Thus some of the entities of B malignancies show typical enzyme patterns which might be of importance in defining maturation stages of the disease. The differences in these enzyme patterns can also be made use of in therapy with enzyme inhibitors such as deoxycoformycin.     

Induction of differentiation and inhibition of DNA methylation in HL-60 myeloid leukemic cells by 5-AZA-2'-deoxycytidine

The effects of 5-AZA-2'-deoxycytidine (5-AZA-CdR) on the induction of morphological and biochemical differentiation and inhibition of DNA methylation of human HL-60 myeloid leukemic cells were investigated. 5-AZA-CdR at concentrations of 0.1-1 microgram ml-1 for 48-h exposure produced significant morphological differentiation of HL-60 leukemic cells to a more mature phenotype, augmented the cell surface marker (OKMI) for mature granulocytes/monocytes and also increased the superoxide anion production. Under these same conditions 5-AZA-CdR inhibited the synthesis of 5-methylcytosine in DNA suggesting that there is a correlation between the induction of differentiation and inhibition of DNA methylation. At concentrations of 5-AZA-CdR that inhibit DNA methylation there was a marked decrease in colony-formation suggesting that the antileukemic action of this analog is related to the methylation of DNA.     

Phenotyping of acute myelomonocytic (AMMOL) and monocytic leukemia (AMOL): association of T-cell-related antigens and skin-infiltration in AMOL

Leukemic blast cells in 25 cases of AMMOL (13 cases) and AMOL (12 cases) were positive for My7 (CD13) and My4 (CD14), while only 44% reacted with LeuM3 (another CD14 MoAb). T-cell-related antigens were detected in 44% of the cases (CD2, 24%; CD4, 12%; CD7 36%). The expression of LeuM3 and TcrAg on blast and monocytic cells was mutually exclusive, with three cases expressing neither LeuM3 nor TcrAg. All six patients with myeloperoxidase negative AMOL and the TcrAG+/LeuM3- phenotype had leukemic skin infiltrations.     

Formation of cytosine arabinoside-5'-triphosphate in cultured human leukemic cell lines correlates with nucleoside transport capacity

The accumulation of cytosine arabinoside-5'-triphosphate (ara-CTP), the activities of nucleotide-metabolizing enzymes and the nucleoside transport capacity were examined in eleven human leukemic cell lines differing in phenotype. The highest amount of ara-CTP was accumulated in T-acute lymphoblastic leukemia cells (T-ALL), followed by myeloid leukemia cell lines (AML), and the least accumulation was observed in common acute lymphoblastic leukemia (c-ALL) and B-acute lymphoblastic leukemia cells (B-ALL). The levels of enzymes involved in ara-C metabolism (deoxycytidine kinase, pyrimidine monophosphate kinase and deoxycytidylate deaminase) did not correlate with ara-CTP accumulation. The sensitivity of the leukemic cell lines to ara-C, which was measured in terms of decrease of clonogenic survival, correlated with the amount of ara-CTP formed. Moreover, the nucleoside transport capacity, estimated from the binding of the radiolabeled nucleoside analogue, [3H]nitrobenzylthioinosine, showed a good correlation with ara-CTP accumulation. The mean numbers of nucleoside-binding sites in T-ALL cells were significantly greater than in B-ALL cells. We conclude that the cellular nucleoside transport capacity is the most important factor for the formation and accumulation of ara-CTP in the cells.     

Terminal deoxynucleotidyl transferase in acute myeloid leukaemia

Between January 1980 and May 1981, 1966 marrow or blood samples from leukaemia patients were tested for terminal deoxynucleotidyl transferase (TdT) using nuclear immunofluorescence. The cells were also tested with a panel of immunological markers including monoclonal antibodies. Of 869 TdT positive cases detected, 555 were diagnosed as ALL and 32 as blast crisis of CGL; 226 were provisionally diagnosed as ‘acute leukaemia’ and finally diagnosed as ALL partly on the basis of immunological data; 56 TdT⁺ cases were provisionally diagnosed as acute non-lymphocytic or myeloid leukaemia; 266 cases of AML and 177 cases of CGL in blast crisis were TdT negative.Eleven of the above ‘AML’ cases were anti-cALL⁺ as well as TdT⁺ and were re-diagnosed and treated successfully as cALL. The remaining 45 were anti-cALL negative and finally diagnosed and treated, at least initially, as AML. Eleven of these cases had only 5–10% TdT⁺ cells which could have been normal, non-myeloid cells. Twenty cases had 11–50% TdT⁺ cells and 14 cases had 50–100% TdT⁺ cells. Of these latter two groups, details on 28 patients were available for evaluation. Three cases on review had no definitive myeloid cytochemistry and were haematologically AUL with a null-ALL phenotype (TdT⁺ DR⁺ cALL^?). In 14 cases there was a large overlap (>75%) of the proportion of cells with myeloid cytochemistry (Sudan black, peroxidase or esterases) and TdT; individual blast cells were therefore expressing these markers concurrently. In the remaining cases, mixtures of TdT negative myeloid and TdT⁺ (lymphoid?) cells may have co-existed although this was not proven unequivocally. Twenty-two cases of newly diagnose TdT⁺ ‘AML’ received induction chemotherapy for AML (DAT regime) and only six (37%) obtained a complete remission.It is concluded that TdT positive ‘myeloid’ leukaemias do occur, albeit infrequently (approx. 5%) and may have a relatively poor prognosis.     

Relation of 5'-nucleotidase and phosphatase activities with immunophenotype, drug resistance and clinical prognosis in childhood leukemia.

Ecto-5'-nucleotidase (ecto-5'NT) catalyzes the extracellular dephosphorylation of nucleotides like IMP. Cytoplasmic 5'NT (cyto-5'NT) and non-specific (e.g. acid- and alkaline) phosphatases (AP) regulate the intracellular degradation of nucleotides. High NT and AP activities might cause a resistance to the thiopurines 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG). We studied the relation between these enzymes and immunophenotype, drug resistance and prognosis in 77 children with acute lymphoblastic leukemia (ALL). Enzyme activities were assessed radiochemically; in vitro drug resistance was measured with the MTT assay. AP activities were higher in T-ALL and B-ALL than in precursor B-ALL. Cyto-5'NT activity was very low in all phenotypes and accounted for a significant proportion of total IMPase activity only in the very immature CD10- c mu- precursor B-ALL. CD10+ ALL cases with high ecto-5'NT activities showed a trend (p = 0.065) for a lower probability of continuous complete remission than those with a low activity. Ecto-5'NT activity was not related to in vitro drug resistance to 6-TG. A weak correlation was found between in vitro 6-TG resistance and cyto-5'NT and AP activities. We conclude that high ecto-5'NT activities do not cause a resistance to 6-thiopurines in childhood ALL. Some patients have high cyto-5'NT and AP activities associated with 6-thiopurine resistance.     

Adult T cell leukemia with atypical surface phenotypes: clinical correlation

The leukemic cells of 57 patients with adult T cell leukemia (ATL) were analyzed for their immunologic surface markers. Forty-four cases showed normal mature inducer/helper T cell phenotype (typical group: E-RFC+, Leu-1+, 2a-, 3a+ MASO36c-), but the other 13 cases showed unusual surface phenotypes (variant group) and could be subdivided into several groups (V1 to V5). Four cases had absent or low Leu-1 positivity (V1: E-RFC+, Leu-1-, 2a-, 3a+, MASO36c-), while two other cases with low Leu-1 positivity had both Leu-2a and 3a, a characteristic of cortical thymocytes, but were unreactive with MASO36c (V2: E-RFC+, Leu-1-, 2a+, 3a+, MASO36c-). Three cases lacked both Leu-2a and 3a despite having other T cell markers (V3: E-RFC+, Leu-1+, 2a-, 3a-, MASO36c-). The next three cases had low rosette-forming ability with sheep RBCs (V4: E-RFC-, Leu-1- approximately +, 2a- approximately +, 3a+, MASO36c-). Interestingly, one other case showed high reactivity against anti-Leu-7, which is believed to be one of the monoclonal antibodies directed against natural killer cells (V5: E-RFC+, Leu-1+, 2a-, 3a+, 7+, MASO36c-). Clinical and hematologic differences between the typical group and variant group were investigated, and it was found that the variant group (excluding V5) have statistically significant (P less than .002) higher serum lactic dehydrogenase (LDH) activity. The overall survival in the variant group was worse than in the typical group, but it was not quite statistically significant (P = .072). The median survival time was eight months for typical cases and only four months for variant cases; six cases died within two months. The V5 case was unusual not only because the patient's leukemic cells have Leu-7 antigen but also because she survived more than nine years after initial diagnosis. There seems to be some correlation between phenotypic diversity of ATL cells and prognosis.     

Aberrant expression of B203.13 antigen in acute lymphoid leukemia of B-cell origin

The B203.13 monoclonal antibody was developed by immunizing mice with the B/monocyte biphenotypic cell line B1b. During normal hematopoiesis B203.13 is expressed on a fraction of CD34+ cells, while on mature cells it is only present on B-lymphocytes. We tested this antibody as a marker of childhood B-acute lymphoblastic leukemia (B-ALL). Bone marrow aspirates from 139 cases of early B-ALL and 25 controls were studied. About 40% of the B-ALL patients expressed B203.13. In these patients, B203.13 was constantly co-expressed with CD10, but never co-expressed with CD20, contrary to the controls. The CD10(+)/B203.13(+) phenotype was specific to B-ALL, since CD10(+)/CD20(+) cells from common acute lymphoblastic leukemia (c-ALL) did not express B203.13. We concluded that the use of B203.13 in association with CD10 and CD20 provides meaningful information for distinguishing normal residual B-cells from leukemic B-lymphoblasts and that recurrence of a CD10(+)/B203.13(+) phenotype after transplantation may be a very early relapse indicator of early B-acute lymphoblastic leukemia.     

Enhanced production of intracellular ara-CTP after sequential use of methotrexate and 1-beta-D-arabinofuranosylcytosine

Synergistic antiproliferative effect has been proven in vitro when mouse leukemic cells were sequentially treated with MTX and ara-C. The mechanism of this combination effect not well elucidated but the intracellular uptake of ara-C was higher when cells were pre-exposed to MTX. In this experiment, the intracellular ara-CTP was measured by HPLC after MTX and ara-C were sequentially administered to BDF1 mice bearing L1210 leukemic cell, either being sensitive or resistant to MTX. When MTX at the dose of 12 mg/kg was preceded 6 h and 3 h to ara-C at the dose of 25 mg/kg, the intracellular levels of ara-CTP were found to be significantly higher as compared with those of ara-C alone as control group. At 1 h after ara-C, ara-CTP was measured about 165 and 130% of the control levels, respectively, and at 12 h, ara-CTP was over 4 times higher of control level with group of mice to which MTX was preceded 6 h prior to MTX. On the contrary, the enhancement of ara-CTP production was definitely diminished with MTX-resistant cells in the same administrative model. From our present experiment, the time sequential modulation of intracellular ara-CTP production by MTX was reconfirmed in vivo, and this modulation might depend upon the sensitivity of MTX of leukemic cells.     

Myeloid differentiation antigens identify leukemic cell subpopulations with different cell cycle characteristics.

In order to assess the proliferative capacity of leukemic subpopulations and to know whether it can be related to the stage of maturation, the expression of two surface antigens identifying distinct steps of leukocyte differentiation (CD15 and CD34) was studied by flow cytometry in correlation with DNA content in 16 cases of acute myeloid leukemia (AML). The surface markers were studied by indirect immunofluorescence, using the monoclonal antibodies VIMD5 (anti-CD15) and MY10 (anti-CD34). The percentage of cells stained by each antibody and the intensity of staining were heterogeneous. Double-staining showed that a small percentage of cells coexpressed both antigens. A correlation was found between the percentage of cells stained by MY10 and the percentage of cells in S + G2 + M in the whole population (p less than 0.05). The percentage of cells in S + G2 + M was significantly higher in MY10-positive than in MY10-negative cells (p less than 0.005), and also higher in VIMD5-positive than in VIMD5-negative cells (p less than 0.005). In the 14 cases expressing both antigens, the percentage of cells in S + G2 + M was higher in VIMD5-positive than in MY10-positive cells (p less than 0.05), whereas there was no difference between VIMD5-negative and MY10-negative cells. It is concluded that the phenotype heterogeneity observed in leukemic cell populations is associated with differences in proliferative capacities. The subset of leukemic cells with the more mature phenotype (CD15-positive) has the highest proliferative activity.     

Comparison of the antileukemic activity of 5-AZA-2'-deoxycytidine, 1-beta-D-arabinofuranosylcytosine and 5-azacytidine against L1210 leukemia

The antineoplastic activity and effect on DNA synthesis and DNA methylation of 5-aza-2'-deoxycytidine (5-AZA-CdR), 1-beta-D-arabinofuranosylcytosine (ARA-C), and 5-azacytidine (5-AZA-CR) on L1210 leukemic cells were compared. At equimolar concentrations 5-AZA-CdR produced greater growth inhibition and more cytotoxicity against the L1210 cells than either ARA-C or 5-AZA-CR. ARA-C, but not 5-AZA-CdR or 5-AZA-CR, produced a potent inhibition of DNA synthesis in the L1210 cells. 5-AZA-CdR and 5-AZA-CR, but not ARA-C, inhibited DNA methylation with 5-AZA-CdR being a more effective inhibitor than 5-AZA-CR. At maximum tolerated dose, 5-AZA-CdR produced a much greater increase in life span of mice with L1210 leukemia than ARA-C or 5-AZA-CR. These in vitro and in vivo studies indicate that 5-AZA-CdR is a more potent antineoplastic agent against L1210 leukemic cells than either ARA-C or 5-AZA-CR.     

Molecular epidemiology of HTLV-I-associated non-Hodgkin's lymphomas in Jamaica

As part of epidemiologic studies of human T-lymphotropic virus (HTLV)-I-associated malignancies in Jamaica, the authors evaluated 26 patients with non-Hodgkin's lymphoma for the presence of integrated HTLV-I provirus in their malignant cells. Fifteen of 26 patients had integrated provirus. All 15 also were HTLV-I antibody positive. Eleven patients did not have integrated provirus, and all 11 were antibody negative. All of the antibody-positive cases had onset of their disease in adulthood (age range, 21-57 years) as opposed to the broad age range of negative cases (4-66 years). Clinical features which were more common in provirus positive than negative patients included leukemic phase, skin involvement, and hypercalcemia, which are all features frequently seen in HTLV-I-associated adult T-cell leukemia/lymphoma (ATLL). The presence of skin involvement, circulating malignant cells, abnormal liver function tests, or the presence of two or more of these four features were statistically significantly different between virus-positive and virus-negative cases. Although the survival of positive cases (6 months) was shorter than that of negative cases (9 months), this was not statistically significant. The only significant determinant of survival was hypercalcemia, with those who developed hypercalcemia at some point in their disease course, independent of their HTLV-I status, surviving a mean of 5 months as compared to a mean of 17.5 months in those who never became hypercalcemic. The six HTLV-I-positive lymphomas that underwent cell typing were all primarily OKT4 positive, whereas two HTLV-I antibody-negative cases that were typed were B-cell lymphomas.     

急性单核细胞白血病M5a和M5b染色体核型及免疫表型的差异

 目的 研究60例急性单核细胞白血病的细胞遗传学、免疫表型和临床特点,分析亚型M5a和M5b之间的差异。方法 采用骨髓直接法和24 h短期培养法制备染色体标本,用G显带技术对60例成年人初发急性单核细胞白血病进行核型分析,用免疫荧光标记法及流式细胞术进行免疫表型检测,同时对其临床资料进行回顾性分析。结果 60例患者中正常核型29例,异常核型31例,其中,正常核型在M5b中出现率高于M5a（P＜0.01）,异常核型中11q23异常和+8染色体在M5a中均较M5b常见（P＜0.01）;单核白血病细胞的免疫表型差异有统计学意义,其中CD68和CD11b在M5a中的表达高于M5b（P＜0.01）;然而,M5a和M5b患者的髓外浸润、外周血白细胞计数、弥散性血管内凝血（DIC）的出现、完全缓解率以及无病生存期（＞1年）之间差异无统计学意义（P＞0.05）。结论 急性单核细胞白血病是一种异质性疾病,其两亚型之间具有各自的细胞生物学特征。     

急性白血病微小残留病检测的临床意义

 目的　探讨应用流式细胞术（FCM）检测急性白血病（AL）患者骨髓微小残留病（MRD）对预测复发及指导治疗的临床意义。方法　选择2005年7月至2008年6月于该院住院经MIC分型确诊的初治获完全缓解（CR）的43例AL患者,应用FCM和单克隆抗体直接荧光标记法检测骨髓MRD,并动态随访。结果　对初次受检MRD阳性患者动态观察骨髓形态学,平均1～3个月复查骨髓1次,所有复发患者均在MRD阳性后4～6个月出现形态学复发。MRD随访结果显示：43例AL患者CR时MRD阴性26例,6例复发,持续阴性20例。CR时MRD阳性17例,10例复发（58.82 %）。4例经加强化疗后MRD转阴达1年以上。43例患者CR时按MRD值水平分为三组,并观察1年复发率。＜1×10-4组和5×10-3～1×10-4组1年复发率差异无统计学意义（P＝0.37）,5×10-3～1×10-4组和＞5×10-3组1年复发率差异有统计学意义（P＝0.02）。结论　应用FCM动态检测MRD对及时预测复发、指导治疗有重要的临床意义。     

An effective,direct immunomagnetic procedure for purging acute lymphoblastic leukemia cells from human bone marrow

The AB4 monoclonal antibody, which recognizes an HLA-DR epitope, was found to bind to a high percentage of malignant blast cells in samples obtained from 27 patients with ALL. These included 11 of 11 cases with c-ALL, 3 of 7 with pre-pre-B, and 8 of 9 cases with pre-B ALL. AB4 was used together with anti CD10 and anti CD19 antibodies and super-paramagnetic particles for developing a direct immunomagnetic procedure for purging human bone marrow of leukemic cells. In model experiments with KM3 cells admixed to mononuclear bone marrow cells, the individual antibodies each removed 2.8–3.1 logs and 3.6–4.1 logs of tumor cells with one and two purging cycles, respectively. In comparison, the efficacy of a mixture of the three antibodies was 4.4 logs with one treatment cycle, and > 5 logs with repeated treatments. Whereas the use of a commercially available anti-HLA-DR antibody resulted in a 90% reduction in the survival of CFU-GMs and normal blast colonies, AB4 had only a moderate effect on the progenitor cells (46% and 30% reduction). In conjunction with autologous transplantation, bone marrow from a patient was purged with the antibody mixture and 50% of the CFU-GMs and 47% of the CD34⁺ cells remained after treatment. The patient showed a normal engraftment, reaching a level of 0.5 × 1071 neutrophils by day 20 and 20 × 107 9/1 platelets by day 30. It is concluded that the antibody cocktail may safely and effectively be used for rapid autograft purging in patients with c-ALL, and also in phenotypically selected cases with other subtypes of ALL. This work was supported by the Norwegian Cancer Society