Immunological and ultrastructural studies in acute biphenotypic leukaemia.

AIMS--To compare the sensitivity of the ultrastructural method to detect myeloperoxidase (MPO) with light microscopy and immunocytochemistry using an anti-MPO antibody; to examine the expression of lymphoid antigens in relation to MPO activity in blast cells from cases of biphenotypic leukaemia. METHODS--Blast cells from 14 cases of biphenotypic acute leukaemia were analysed. Immunological markers were performed by single or double immunofluorescence staining on a flow cytometer. The presence of MPO was determined by light microscopy, electron microscopy on fixed and unfixed cells, and by immunoalkaline phosphatase with an anti-MPO antibody. The immunogold method was applied at the ultrastructural level to assess the expression of lymphoid and myeloid antigens at the same time as the MPO activity. RESULTS--Six of the 14 cases were initially classified as acute lymphoblastic leukaemia (ALL) and eight as acute myeloid leukaemia (AML). MPO activity was shown at the ultrastructural level in 4-99% blasts from all cases. Six of the 14 were MPO negative by light microscopy and three of these were negative with the antibody anti-MPO. Coexpression of lymphoid antigens (CD19, CD10, or CD2) and MPO was shown by the immunogold method in four out of 11 cases; in seven cases the blasts coexpressed myeloid antigens (CD13, CD33) and MPO. CONCLUSIONS--Electron microscopy is more sensitive for showing MPO than light microscopy and immunocytochemistry; the immunogold method combined with MPO used at the ultrastructural level can help to define the cell lineage involved in biphenotypic leukaemia by highlighting the myeloid component defined by MPO.     

Plasma soluble interleukin-2 receptor (sIL-2R) levels in patients with acute leukemia

The plasma soluble interleukin-2 receptor (sIL-2R) level was higher in 137 patients with acute leukemia (1,489 +/- 1,798 U/ml, including 98 cases of acute myeloid leukemia (AML), 1,063 +/- 1,414 U/ml, and 39 cases of acute lymphoblastic leukemia (ALL), 2,561 +/- 2,194 U/ml), compared to 49 normal control subjects, 421 +/- 151 U/ml). The ALL patients showed elevated plasma sIL-2R levels more frequently than the AML patients (92.3% vs 44.9%). No patient with either hypoplastic AML or AML with multilineage dysplasia and only 1 of 13 patients with acute promyelocytic leukemia (APL) had an elevated plasma sIL-2R level. All the My+ ALL patients (15 cases) showed elevated plasma sIL-2R levels. Plasma sIL-2R levels were significantly lower after chemotherapy in the ALL patients, but were not significantly lower in the AML patients. IL-2R was expressed on the leukemic cells in 36 (53.7%) of 67 AML and in 9 (21.4%) of 42 ALL cases. None of the AML M3, M4, M5, M6, or M7 subgroups showed IL-2R expression. The My+ ALL patients (42.9%, 6/14) showed IL-2R expression more frequently than the other ALL subgroups (10.7%, 3/28) (p = 0.025). The plasma sIL-2R level was correlated with the proportion of leukemic cells expressing IL-2R in acute leukemia. However, there were many cases, particularly ALL cases, who had elevated plasma sIL-2R levels without IL-2R expression on their leukemic cells. These results suggest that the plasma sIL-2R level is a valuable marker for monitoring ALL after chemotherapy, particularly in My+ ALL cases, and that the T cell immune reaction to leukemia appears to be much higher in ALL patients than in AML patients.     

The value of the ultrastructural pattern of myeloperoxidase and platelet peroxidase in identification of two blastic cell types during transformation of a chronic myeloproliferative disorder

The value of the ultrastructural pattern of myeloperoxidase (MPO) and plateletperoxidase (PPO) staining is evaluated for the identification of the type of blastic cells during the acute transformation of a chronic myeloproliferative disorder. MPO and PPO are generally accepted as lineage specific markers for the detection of myeloid or megakaryocytic differentiation of the blast cells. The ultrastructural pattern of myeloperoxidase (MPO) and plateletperoxidase (PPO) permitted us to identify two types of blastic cells (one from the myeloid and the other from the megakaryoblastic lineage) in the acute transformation of a chronic myeloproliferative disorders.     

Periodic acid-Schiff reaction and prognosis in lymphoblastic leukaemia.

Diagnostic bone marrow smears from 132 patients with acute lymphoblastic leukaemia, (ALL) were stained simultaneously by the periodic acid-Schiff (PAS) reaction, and the blast cell positivity was assessed quantitatively. The patients fell naturally into two unequal groups: those with more than 20% PAS-positive blast cells (44 patients) and those with less (88 patients). There was no relation between the degree of positivity and age, sex, or presenting leucocyte count. Actuarial survival studies showed that the group with more than 20% PAS-positive blast cells survived longer, but that this difference assumed statistical significance only after the exclusion of patients over 14 years old and those with high white cell counts at the time of diagnosis. It appears that the PAS reaction can identify long survivors among patients with ALL, but not in the absence of features strongly associated with a poor prognosis.     

Laboratory features of acute myelogenous leukemia in elderly patients

The hematologic features of 103 AML patients older than 60 years(elderly patients) were analysed. Prior to AML a myelodysplastic state was noted in 28% of those patients, 39.3% of patients had a white blood cell count below 3000/microliter, and in 25%, no blast cells were detected in the peripheral blood. Hypoplastic marrows were noted in 25.2%. In regard to the subtypes, M3 was noted less frequently in the elderly patients than in the younger patients. CD34 in blast cells was observed in 53% of patients and dysplastic changes in bone marrow cells other than blast cells were observed in 46% of elderly patients. Chromosomal abnormalities with good and poor prognosis were noted in 3.1% and 25.0% of patients respectively, and the most commonsites for chromosomal abnormalities were chromosomes 5 and 7. MDR1 abnormality was detected more frequently in the elderly patients(68%) than in younger AML patients(38%). We speculated that the laboratory features of the elderly AML patients may be related to the aging of bone marrow and the effects of environmental factors.     

Comparative genomic hybridization in childhood acute lymphoblastic leukemia: correlation with interphase cytogenetics and loss of heterozygosity analysis

We used comparative genomic hybridization (CGH) to study DNA copy number changes in 71 children with acute lymphoblastic leukemia (ALL) including 50 B-lineage and 21 T-ALLs. Forty-two patients (59%) showed genomic imbalances whereby gains were more frequently observed than losses (127 vs. 29). Gains most commonly affected the entire chromosomes 21 and 10 (19.7% each), 6, 14, 18, X (15.5% each), 17 (14.1%) and 4 (11.3%). Highly hyperdiploid karyotypes (chromosome number >50) occurred more frequently in B-lineage than in T-lineage ALL (24% vs. 4.8%). In both cell lineages deletions were mainly detected on 9p (14.1%) and 12p (8.4%), and on 6q in T-lineage ALL (4.2%). These findings were compared with loss of heterozygosity (LOH) of 6q, 9p, 11q, and 12p previously performed in 56 of the 71 patients. Among 54 sites of LOH, CGH revealed losses of the respective chromosome arms in 17 LOH-positive regions (31.5%). G-banding analysis and interphase cytogenetics with subregional probes for 14 loci confirmed the presence of genomic imbalances as detected by CGH. We, therefore, conclude that, in the absence of cytogenetic data, CGH represents a suitable method for identifying hyperdiploid karyotypes as well as prognostically relevant deletions in ALL patients.     

Vascular endothelial growth factor C--a potent risk factor in childhood acute lymphoblastic leukaemia: an immunocytochemical approach

AIMS: To investigate the immunocytochemical expression of vascular endothelial growth factor C (VEGF-C) and its receptors (VEGFR-2 and VEGFR-3) in childhood acute lymphoblastic leukaemia (ALL) blasts and to determine the possible role of this complex in the pathogenesis and prognosis of ALL. METHODS AND RESULTS: Bone marrow samples were taken from 120 children diagnosed with ALL. An indirect immunocytochemical procedure was performed with the use of monoclonal mouse anti-human antibodies against VEGF-C, VEGFR-2 and VEGFR-3 (diluted 1 : 100). The immunocytochemical expression of VEGF-C was confirmed exclusively in the cytoplasm of ALL lymphoblasts (the mean percentage was 36.4 +/- 7.2). It was absent from the cytoplasm of normal haematopoietic cells in the control group. No VEGFR-2 or VEGFR-3 expression was detected in the children of either the study or control groups. The risk of induction failure or leukaemic relapse was found to be significant in all VEGF-C+ patients (P < 0.0001 and P < 0.02, respectively; Fisher's exact test). CONCLUSIONS: The absence of VEGF-C in blast cells predicts long-lasting remission in all leukaemic children. Our findings also suggest that leukaemic cell invasion, following VEGF-C-driven lymphangiogenesis, could be related to a mediating role of this peptide produced by blast cells themselves.     

Cytokine production in whole blood cell cultures of patients with B-lineage acute lymphoblastic leukemia. The influence of granulocyte-macrophage colony-stimulating factor

We investigated the levels of 6 different cytokines in the sera of 10 newly diagnosed patients with B cell lineage acute lymphoblastic leukemia (ALL) and detected a significant increase in IL-6 and IFN-alpha serum levels in comparison to that of healthy controls. Whole blood cell cultures of 10 ALL patients and 20 control individuals were induced with classical cytokine inducers, such as virus, PHA and LPS, and their ability to produce 9 different cytokines was compared. Blood cells of ALL patients produced significantly less IL-1alpha, IL-1beta, IL-10 and TNF-alpha than control cells and not significanly lower levels of IL-6, but comparable with control levels of IL-2, IL-4. rHuGM-CSF added to cell cultures 24 h before induction significantly enhanced the production of IL-1alpha, IL-1beta and TNF-alpha in controls, but only IL-1alpha and IL-1beta in the blood cell cultures of patients with ALL. GM-CSF did not significantly influence the production of IFN-alpha, IFN-gamma, IL-2, IL-4 and IL-10 in the control cells and the cells of ALL patients. The patients examined differed not only in the expression of CD10 and CD34 antigens on blast cells, but also in the reaction to GM-CSF treatment, which was found as very high standard deviation values. We suppose that these differences can partially explain the different effects of GM-CSF when used to ameliorate neutropenia of ALL patients after chemotherapy and to reduce the incidence of microbial infections.     

A study on the incidence of ABL gene deletion on derivative chromosome 9 in chronic myelogenous leukemia by interphase fluorescence in situ hybridization and its association with disease progression

Fluorescence in situ hybridization for the BCR/ABL rearrangement in 138 bone marrow specimens from 59 Philadelphia(+) (Ph(+)) chronic myelogenous leukemia (CML) patients, 35 Ph(+) acute lymphoblastic leukemia (ALL) patients, and 57 Ph(-) ALL patients was used. Sixteen (27.1%) of the 59 CML patients had deletions of the residual ABL gene on the derivative chromosome 9. During the study period, 32 of the 59 CML patients progressed to blast crisis or accelerated phase. Of these, nine patients had residual ABL gene deletions on the derivative chromosomes 9 and 23 patients had no deletions. The mean duration from first diagnosis to blast crisis or accelerated phase for the nine patients with ABL deletions was 32.8 months, and for the 23 patients without ABL deletions, it was 62.4 months (P = 0.017). The overall survival time for the 16 patients with deletions was 32.8 months, and for the 43 patients without deletions, it was 60.1 months (P = 0.164). ABL deletions were not detected among the 35 ALL patients (17 with major BCR/ABL, 18 with minor BCR/ABL), and it appears that this deletion occurs rarely or not at all in Ph(+) ALL patients, which is in contrast to the CML patients (27.1%). However, we detected two ALL cases with ABL deletion but without BCR/ABL rearrangement among 49 Ph(-) ALL and 66 Ph(-) AML patients. In conclusion, patients with ABL deletions progress to blast crisis or accelerated phase in a significantly shorter time than do those without such deletions. It is therefore suggested that the ABL deletion is an indicator of a poor prognosis in CML.     

Myeloperoxidase gene expression in acute leukemias

Since myeloperoxidase (MPO) is considered to be a critical marker of differentiating acute myelogenous leukemia (AML) from acute lymphocytic leukemia (ALL), the analysis of MPO gene expression may provide further insight into the leukemia classification and the lineage fidelity of leukemia cells. By Northern blot hybridization using full-length MPO cDNA as a probe, approximately 66% of AML cells (3/4 M1 cases, 2/4 M2 cases, 15/15 M3 cases, 11/15 M4 cases, and 2/12 M5 cases) were found to express MPO mRNAs, whereas none of 18 ALL cases did. MPO mRNA was detectable when AML cells contained at least 10% peroxidase-positive cells. APL (M3) cells expressed high levels of mRNA in accordance with heavy staining for peroxidase.     

Simultaneous evaluation of terminal deoxynucleotidyl transferase and myeloperoxidase in acute leukemias using an immunocytochemical method

The classification of acute leukemia is important for the selection of optimal therapy. Classification often rests on morphologic, cytochemical, and immunologic criteria, and the marker enzyme terminal deoxynucleotidyl transferase (TdT) has been considered to be a reliable indicator of lymphoblastic leukemias. Because TdT-positive cells sometimes are seen in leukemias otherwise identified as myeloblastic, the authors evaluated blasts identified as myeloid by the presence of myeloperoxidase (MPO) for the simultaneous expression of TdT. The blasts in the bone marrow aspirate or peripheral blood of unselected patients with hematologic malignancies were evaluated and 60 cases are shown. The French-American-British system and, in some patients, cytochemical and immunologic studies were used to classify the leukemias. The authors demonstrated that blasts simultaneously contained MPO and TdT in 29% of patients with acute myeloblastic leukemia and 3% of patients with acute lymphocytic leukemia (ALL). This finding supports the hypothesis that TdT is an expression of cell primitivity rather than a marker for lymphoblastic cells.     

Value of monoclonal anti-myeloperoxidase (MPO7) for diagnosing acute leukaemia.

The expression of myeloperoxidase (MPO) was studied in 100 cases of acute leukaemia (83 with acute myeloid leukaemia (AML) and 17 acute lymphoblastic leukaemia (ALL) by both a conventional cytochemical method and the immunocytochemical antiperoxidase (APAAP) technique using the monoclonal antibody MPO7. In each case the staining was evaluated by light microscopical examination (percentage of positive cells). Of the 83 cases of AML, 78 (93.9%) were positive for MPO7 compared with 70 (84.3%) by cytochemistry. Antibodies against the myeloid markers CD13 and CD33 were positive in 71 (85.5%) and 70 (84.3%) cases, respectively. Importantly, all cases of ALL were negative for both MPO7 and cytochemical MPO staining even when they were positive for CD13 and CD33. These results indicate that the anti-myeloperoxidase antibody MPO7 is the most sensitive and specific reagent for the diagnosis of AML and should therefore be included in routine immunophenotyping panels.     

Myeloperoxidase expression in acute myeloid leukemia helps identifying patients to benefit from transplant

Purpose

Despite extensive study, the use of allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia (AML) vary considerably. The decision of which of these options to choose is complex and depends on both clinical and molecular variables as well as the availability and histocompatability of donor stem cells. So far there is no clear explanation on whether the expression of myeloperoxidase (MPO) relates to the prognosis of AML.

Materials and Methods

We retrospectively analyzed the prognostic significance of the MPO expression in the 140 patients with diagnosed AML treated at a single institution.

Results

In our study, MPO expression was associated with disease-free survival (DFS) and transplant was beneficial to overcome a negative prognostic effect of MPO-negative at diagnosis based upon the result that the DFS in patients received transplants are not significant between the MPO-positive group and MPO-negative group although DFS in all patients was different according to MPO expression.

Conclusion

MPO expression at diagnosis helps to choose therapy for each AML patient and can differentiate AML patients who need transplantation.     

急性淋巴细胞白血病患者FGFR3表达对循环内皮细胞增殖的影响

目的:了解急性淋巴细胞白血病(ALL)患者成纤维细胞生长因子受体3(FGFR3)表达对循环内皮细胞(CECs)增殖的影响。方法:通过RT-PCR法检测44例ALL患者骨髓中FGFR3 mRNA表达,分成FGFR3~+组及FGFR3~-组进行Kaplan-Meier生存分析。利用免疫磁珠结合流式细胞术分离计数CECs,对比两组CECs数量、表面抗原表达、生长曲线及集落生成数的差异。免疫荧光组化染色测定CECs表面FGFR3表达水平。结果:44例核型正常ALL患者中FGFR3 mRNA表达阳性率为43.2%,T-ALL组的FGFR3表达高于B-ALL组(P0.05)。19 d骨髓原始细胞比例≥5%的患者FGFR3表达升高(P0.05)。FGFR3阳性组的总生存率明显低于阴性组(P0.05)。分离出的CECs高表达CD31、CD144、VEGFR-2和CD146,基本不表达CD45。与FGFR3阴性组相比,阳性组CECs数量、CD133的阳性率及集落生成数均增多(P0.05)。体外培养中,FGFR3阳性组与阴性组相比,生长曲线3个时点上的细胞数差异有统计学显著性(P0.05)。19例ALL-FGFR3~+患者CECs表面均能检测到FGFR3表达,阳性率为29.00%±15.71%。结论:致癌基因FGFR3对ALL患者CECs的增殖有促进作用,可能具备了抗肿瘤及抗血管生成的双重靶点身份,可以为今后的分子治疗提供更多的选择。     

Dasatinib

Dasatinib is a small-molecule inhibitor of multiple tyrosine kinases, including BCR-ABL, SRC, c-KIT, ephrin A receptor and platelet-derived growth factor-beta receptor kinases, at nanomolar concentrations. In vitro, dasatinib is 325-fold more potent than imatinib against cells expressing wild-type BCR-ABL. The efficacy and tolerability of oral dasatinib has been established in the START phase II trials in adults with chronic myeloid leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-positive ALL) who were intolerant or resistant to imatinib, and optimal dasatinib dosage regimens were identified in phase III randomized trials. In patients with chronic phase CML, the major cytogenetic response rate in the START-C trial (median follow-up 15.2 months) was 59% with dasatinib, and in the randomized START-R trial (median follow-up 15 months), was greater with dasatinib than with high-dose imatinib (52% vs 33%). Major hematologic response rates with dasatinib were 63% in patients with accelerated phase CML (follow-up > or =9 months; START-A trial), 34% in patients with myeloid blast phase CML and 35% in those with lymphoid blast phase CML (follow-up > or =12 months; START-B and START-L trials), and 41% in patients with Ph-positive ALL (follow-up > or =12 months; START-L trial). Based on phase III results, a once-daily dasatinib regimen is considered optimal in chronic phase CML (starting dosage 100 mg once daily), while a twice-daily regimen continues to be recommended in accelerated phase, myeloid blast phase or lymphoid blast phase CML and Ph-positive ALL (starting dosage 70 mg twice daily). Adverse events were frequent in patients treated with dasatinib, but most were mild to moderate in severity. Grade 3/4 adverse events were uncommon and were clinically manageable.     

Periodic acid Schiff reaction in childhood lymphoblastic leukaemia. The Medical Research Council Working Party on Childhood Leukaemia.

AIMS--To assess the prevalence and degree of periodic acid Schiff (PAS) positivity in blast cells from children with lymphoblastic leukaemia (ALL); its association with other disease characteristics; and its clinical importance in predicting the outcome of treatment. METHODS--Marrow slides from entrants to a large United Kingdom multicentre ALL trial (UKALL X) were batch processed and assessed blind for PAS positivity by one morphologist. Patients were classified into groups A, B, and C, corresponding to less than 1% PAS positive cells, 1-10%, and over 10%, respectively. Their PAS pattern was then compared with other clinical and pathological features of ALL and with treatment outcome. RESULTS--Slides from 921 children were examined of which 371 (40%) were categorised as group A, 324 (35%) as group B, and 226 (25%) as group C. There was a clear association between the presence of blast cell vacuoles on Romanowsky staining and PAS positivity. Group A (PAS negative) patients included a disproportionate excess of those with L2 morphology, those under 2 or over 6 years of age, those with an initial white cell count over 50 x 10(9)/l, those with a T or null cell immunophenotype, and those with chromosomal abnormalities other than "high hyperdiploidy". Four years from diagnosis, group C patients had an 8% disease free survival advantage over those in group A (2p = 0.01). This was irrespective of initial white cell count, but not of immunophenotype or the presence of vacuoles. CONCLUSIONS--Strong PAS positivity is a feature of "common" ALL and is particularly associated with blast cell vacuoles. It does occasionally occur in other disease subtypes with or without vacuoles. It predicts a better response to current treatment, but not independently of other cell characteristics.     

The ultrastructure of hybrid acute leukemia: a study of 15 cases

The objective of this study was to investigate the ultrastructural characteristics of hybrid acute leukemia (HAL). Fifteen cases of HAL were studied by transmission electron microscopy (TEM), focusing on organelles and myeloperoxidase (MPO) reaction of leukemic cells. By TEM, 5 out 15 cases of HAL were consistent with immunophenotyping (3 cases of biphenotypic type, and 2 cases of biclonal type with granulocytes and lymphocytes); 2 cases were suspected as HAL. On other hand, 5 cases of HAL were assigned to ALL, and 2 cases were misinterpreted as M5a and 1 as M4b. Most of the blast cells of biphenotypic HAL showed lymphoid features, except some cases containing MPO positive granules in blasts, while a few cases exhibited monocytic or nonspecific features. TEM offers advantages in the diagnosis of biclonal type HAL and biphenotypic HAL positive for MPO. However, it is difficult to differentiate MPO-negative cases of biphenotypic HAL from ALL and a few cases may be misinterpreted as M5 by TEM.     

Significance of microRNA-16 and bcl-2 expression in T lymphoblastic lymphoma/leukemia and its relation with prognosis北大核心CSCD

Objective: To study the expression of miR-16 and bcl-2 in T lymphoblastic lymphoma/leukemia (T-LBiyALL) and its relationship to prognosis. Methods: 70 cases of T-LBL/ALL with follow-up data were studied by using immunohistochemical EnVision method for CDla,CD3, cCD3, CD7, CD10, CD20, CD23, CD34, CD43, CD45RO, CD99, TDT, MPO, bcl-2 and Ki-67. The expression levels of miR-16 were examined by TaqMan real-time polymerase chain reaction (RT-PCR). Thirty cases of reactive lymph node were selected as control. Results: Among the 70 cases of T-LBL/ALL, the percentages of tumor cells expression of TDT, CD99, CD3, CD7.CD10, CD34, CDla,cCD3, bcl-2, CD45RO and CD43 were 94. 3% (66/70), 94. 3% (66/70), 68. 6% (48/70), 92. 9% (65/70), 32. 9% (23/70), 24. 3% (17/70), 40. 0% (28/70), 51. 4% (36/70), 34. 3 % (24/70), 37. 1 % (26/70), and 48. 6% (34/70). Separately, while tumor cells expression of MPO, CD20 and CD23 was all negative. A figure of Ki-67 expression > 80% was found in 24 cases and ≤ 80% in 46 cases. The expression of miR-16 was up-regulated in T-LBL/ALL, and it was 5. 07 times of the reactive lymph node(P = 0. 001). The high expression group of miR-16 was significantly correlated with longer over survival (P = 0. 041). The prognosis of negative bcl-2 group was better than bcl-2 positive one(P =0. 904). The relationship of miR-16 and bcl-2 was significant P =0. 042, x2=4. 147). Survival multivariate COX proportional hazard regression analysis revealed that the low expression of miR-16 might be a independent poor prognosis factor (P =0.049). Conclusions: While the high expression group of miR-16 has longer OS than that in low expression group. The prognosis of bcl-2 negative was better than bcl-2 positive. miR-16 may be a independent prognosis factor. The relationship of miR-16 and bcl-2 might suggested that gene regulation may be influenced by them.     

ETV6/CBFA2 fusions in childhood B-cell precursor acute lymphoblastic leukemia with myeloid markers.

A translocation resulting in a fusion of ETV6 (TEL) gene at 12p13 and CBFA2 (AML1) gene at 21q22 is variably reported in 16-36% of cases of childhood acute lymphoblastic leukemia (ALL). This t(12;21)(p13;q22) is not detectable by conventional cytogenetic methods and was reported to be associated with B-cell precursor ALL with presumed favorable prognosis. We have examined 18 cases of well characterized childhood B-cell precursor ALL with cytogenetic, immunophenotypic, and clinical data for the presence of the t(12;21) using fluorescence in situ hybridization (FISH). Fourteen of the 18 cases (78%) were positive for fusion ETV6/CBFA2. One of seven adult ALL patients was positive (12% of cells positive in this 21 year old patient). By contrast, no evidence of t(12;21) by FISH was noted in two childhood T-ALL cases and 10 normal bone marrow samples. Twelve of the 14 positive childhood cases had CD13 and/or CD33 expression (myeloid markers) while only one of the four negative cases was CD13 and CD33 positive. Eight of 12 cases positive for t(12;21), and with conventional cytogenetic data, had structural and/or numerical chromosome abnormalities other than the detected t(12;21). One case had relapse with gradual increase in percentage of cells positive for t(12;21) and development of an isochromosome 21 carrying the fusion signals. The data reveal a strong association of t(12;21) with B-cell precursor ALL, especially with myeloid marker expression.     

Hyperglycemia triggers massive neutrophil deposition in brain following transient ischemia in rats

Myeloperoxidase (MPO) immunohistochemistry was used to ascertain the role of polymorphonuclear leukocytes in hyperglycemia-induced accentuation of brain injury after transient ischemia. Rats received 12.5 min of normothermic global cerebral ischemia by bilateral carotid occlusion plus hypotension. Hyperglycemia was induced before ischemia by intraperitoneal dextrose administration. Quantitative MPO immunohistochemistry was performed at 24 h and 3 days postischemia. Brains of normoglycemic-ischemic animals contained almost no MPO activity. By contrast, striking numbers of MPO-positive cells were present in brains studied 24 h after hyperglycemic ischemia, both within pial and parenchymal vessels and within the parenchyma. MPO deposition tended to subside at 3 days. These results indicate that hyperglycemia triggers the early, massive deposition of neutrophils in the postischemic brain--an event that may contribute to exacerbation of injury.