Effects of recombinant human G-CSF and GM-CSF on primary human leukemic cells

The effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on primary human leukemic cells were studied. Phagocyte-depleted mononuclear cells containing more than 88% blasts were obtained from peripheral blood of 11 AML and 2 ALL patients and from bone marrow aspirates from 2 ALL patients. The leukemic cells were incubated with these CSF in suspension cultures or in methylcellulose cultures. In suspension cultures, the spontaneous proliferation was observed in 1 M4 patient. RhG-CSF stimulated the leukemic cell proliferation in 5 AML, cases and rhGM-CSF that in 4 AML cases. In methylcellulose cultures, spontaneous colony formation occurred in 3 M4 patients. RhG-CSF and rhGM-CSF stimulated the leukemic colony formation in 8 AML cases. The CSFs had an additive effect in both cultures. Neither CSF induced O2- production or phagocytic activity. From these results, we concluded that both CSFs stimulated the proliferation of leukemic cells without inducing differentiation.     

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.     

Membrane and intracellular platelet-activating factor receptor expression in leukemic blasts of patients with acute myeloid and lymphoid leukemia

Platelet-activating factor (PAF), a phospholipid mediator with a wide range of actions on mature leukocytes, acts through PAF-receptors (PAF-Rs) on the membranes of responsive cells. No results are available concerning the putative presence of PAF-Rs on leukemic blasts. Using multiparameter flow cytometry, we assessed intracellular and membrane PAF-Rs on blast cells of acute myeloid leukemic (AML) and acute lymphoid leukemic (ALL) patients. Membrane PAF-Rs were documented in 7/15 cases of ALL and 0/28 cases of AML. Putative intracellular PAF-Rs were found in blasts of 8/8 ALL and 13/13 AML patients. Vitamin D(3) and dimethyl sulfoxide that induced the expression of PAF-Rs on the membrane of the human promyelocytic leukemia cell line, HL60, failed to induce their expression on the membranes of CD34(+) AML blasts. The lack of membrane PAF-Rs on the membranes of AML blasts confirms that these receptors represent a marker of mature cells and that their membrane induction is a consequence of cell maturation and differentiation.     

Fluorescence in situ hybridization analysis of whole-arm 7;12 translocations in hematologic malignancies

Cytogenetic analysis of one case of acute myeloid leukemia (AML), one of acute lymphoblastic leukemia (ALL), one of refractory anemia with excess of blasts (RAEB), and one of acute mixed lineage leukemia (AMLL) with unbalanced 7;12 translocations mapped the breakpoints to the centromeres on both chromosomes. The rearrangements were interpreted as the whole-arm translocations der(7;12)(q10;q10) in the AML and ALL and der(7;12)(p10;q10) in the RAEB and AMLL. However, further analysis by metaphase and/or interphase fluorescence in situ hybridization (FISH) showed centric fusion only in the AML and ALL. In the RAEB and AMLL, centromeric material from chromosome 7 but not from 12 was present in the derivative chromosome. Whereas the t(7;12) resulted in loss of 12p in all four cases, the corresponding chromosome 7 imbalances differed—monosomy for 7q in the RAEB and AMLL and monosomy for 7p in the AML and ALL. Six hematologic neoplasms with unbalanced whole-arm or near-centromeric 7;12 translocations and seven dic(7;12) with juxtacentromeric breakpoints have been reported previously: 2 AML, 1 RAEB in transformation, and 10 ALL. All karyotypically informative cases had loss of 12p material. All but one of the cases with combined 7p and 12p deletion were ALL, whereas all cases with 7q and 12p loss showed myeloid differentiation. No particular clinical, morphologic, or immunophenotypic features seem to characterize ALLs with t(7;12). AMLs with an unbalanced t(7;12), often together with 5q deletions, might be associated with previous genotoxic exposure and poor prognosis.     

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.     

Cytokine-driven differentiation of blasts from patients with acute myelogenous and lymphoblastic leukemia into dendritic cells

We investigated the ability of both acute myelogenous leukemia (AML) and acute lymphoblastic leukemia (ALL) blasts to differentiate into dendritic cells (DC) in vitro. Cytokine-supplemented suspension cultures of leukemic blasts in 98 patients with AML and five patients with ALL (normal karyotype, n = 2; BCR/ABL, n = 3) were performed. Mononuclear cells out of peripheral blood or bone marrow containing between 60% and 90% leukemic blasts were cultured for eight days using different growth factor combinations. The highest yield of CD1a(+)/CD14(-) cells could be obtained with stem cell factor, transforming growth factor-beta, tumor necrosis factor-alpha, GM-CSF, and FLT-3-ligand. In the AML samples the median content of CD1a(+)/CD14(-) cells after eight days of culture was 3.5% (r = 0%-82%). In five informed patients CD1a(+)/CD14(-) cells were sorted by fluorescence-activated cell sorting or immunomagnetic separation. Cytogenetic and polymerase chain reaction analyses showed known primary chromosomal aberrations (monosomy 7 and inversion 16) in the sorted fractions, respectively. Dendritic cells (DC) could be generated out of leukemic blasts in 68% of AML patients. Leukemic DC showed no phagocytosis of latex beads, but stimulated allogeneic naive cord blood-derived T cells more efficiently than did uncultured blasts. In ALL patients the median percentage of CD1a(+)/CD14(-) cells was 1.2% (r = 0.7%-3.8%) after culture. The sorted CD1(+)/CD14(-) fractions were BCR/ABL-negative when analyzed with fluorescence in situ hybridization, indicating their nonleukemic origin. Leukemic DC can be generated out of leukemic progenitors in patients with AML. These cells might become relevant for autologous and allogeneic immunotherapy in selected patients. BCR/ABL-positive lymphoblasts could not be transformed into cells with an early dendritic phenotype with the cytokines used in our experiments.     

Assessment of proliferative activity in leukaemic bone marrow using the monoclonal antibody Ki-67.

AIMS--To investigate proliferative activity in leukaemic and lymphomatous bone marrow infiltrates and to assess the feasibility of transport of specimens among institutions. METHODS--Proliferative activity in bone marrow trephine cryosections from 99 patients with non-Hodgkin''s lymphoma (NHL), 23 patients with acute myeloid leukaemia (AML), 11 with acute lymphoblastic leukaemia (ALL), and two with acute undifferentiated leukaemia (AUL) was investigated. Infiltration was seen in 52 out of 99 cases of NHL on bone marrow cryosections. A score was devised to assess pathological infiltrates in bone marrow trephine cryosections using the monoclonal antibody Ki-67. This method of scoring gave a measure of non-erythroid proliferative activity. RESULTS--Mean Ki-67 positivity in bone marrow infiltrates in 31 low grade B cell lymphomas (Kiel classification) was 0.3% before and 4.7% after treatment, 16.4% in seven high grade B cell lymphomas, and 17.8% in 12 peripheral T cell lymphomas. In 48 cases of NHL, bone marrow cryosections had not been infiltrated, and in all but one case the percentage of Ki-67 positive cells in normal marrow was less than 3%; the remaining case showed coexistent myelodysplasia and 8% bone marrow Ki-67 positivity. In eight cases of common ALL at diagnosis, the mean Ki-67 positivity in marrow cryosections was 24.9%, significantly higher than the 2.4% Ki-67 positivity seen in AML (p < 0.05). One of the two cases of common ALL with less than 1% Ki-67 positivity was refractory to treatment. CONCLUSIONS--Proliferative activity of erythroid elements in the bone marrow varies greatly. Immunostaining of bone marrow cryosections using Ki-67 permits accurate assessment of non-erythroid proliferative activity in lymphomas and leukaemia. High grade B cell lymphomas and peripheral T cell lymphomas invading the marrow have very similar mean proliferative activities. Such levels of proliferation are of the same order as those seen in common ALL, but much higher than those seen in AML.     

Differentiation of monocytes into CD1a- dendritic cells correlates with disease progression in HIV-infected patients

Monocyte differentiation into dendritic cells (DCs) depends on microenvironmental conditions. In this study, the capacity of human monocytes to differentiate into mature DCs and their ability to induce an antiviral immune response was investigated in HIV-infected patients. In healthy subjects, monocytes differentiate into CD1a+ DCs in the presence of granulocyte macrophage colony-stimulating factor and interleukin (IL)-4 and matured in the presence of lipopolysaccharide. Here, we found that in 30% and 45% of HIV-infected white and African subjects, respectively, monocytes gave rise to a homogeneous CD1a* DC population. In the patients who gave rise only to the CD1a* DCs, this population spontaneously produced IL-10 but not IL-12, and induced a T helper 2-like immune response when cultured with human T cells isolated from cord blood mononuclear cells. In patients with monocytes differentiated into CD1a* DCs, a high percentage of HIV-specific CD4 T cells producing IL-4 were seen in the peripheral blood. Furthermore, differentiation of monocytes into DCs with CD1a* phenotype correlated with low CD4 T-cell counts and high viral loads in HIV-infected subjects. These results suggest that the differentiation of monocytes into CD1a* DCs may be a phenotypic marker associated with progression of the disease.     

Study of tumor cells sensitivity in patients with acute leukemia to cytokines and their combined use with drugs in vitro by MTT analysis

MTT analysis has yielded data on the sensitivity of leukemia cells isolated from 64 patients with acute leukemia to the cytokines G-KSF?, GM-KSF, interferon-alpha 2b and their combined use with drugs, such as cytosar, vepeside, doxorubicin, vincrastine, L-asparaginase. The mean in vitro survival of leukemia cells in children with acute lymphoblast cell leukemia (ALCL) was 1.9 times less than that in acute myeloblast cell leukemia (AMCL) (p < 0.001), that in new cases of ALL was 2.3 times less than in relapses (p = 0.024). The stimulating effect of GM-KSF on the survival rates of leukemia cells was seen in 64.7% of patients with AML. That of GM-KSF was recorded in 21.4% of cases. The survival of lymphoblast cells isolated from children with ALL did not differ greatly in the absolute majority of cases (by more than 30%) in the presence of growth factor in the medium. The cytotoxicity of XII with medium growth factor decreased in most cases. However, some cases (more frequently in AML than ALCL) displayed a higher cytotoxicity of XII, particularly cytosar in the presence of G-KSF and GM-KSFG; LC50 of Ara-C decreased by 30% or more in the presence of growth factor in 36% of patients. Incubation with interferon alpha 2b caused a reduction in the survival of leukemia cells, which was more pronounced in children with ALL. Interferon-alpha 2b caused an increase in the cytotoxic effect of XII on leukemia cells in ALL to a greater extent; cytosar, vepeside, and doxorubicin enhanced the effect by 1.47, 1.39, and 2.35 times, respectively.     

Leu-M1 antigen expression in acute leukaemias

Leu-M1 is a differentiation antigen present in human myelomonocytic cells. Seventy-seven acute leukaemias were retrospectively stained with anti-Leu-M1 using the immunoperoxidase technique on Bouin-fixed paraffin-embedded sections. The subjects were 44 acute lymphoblastic leukaemias (ALL) and 33 acute myeloid leukaemias (AML) previously characterized by cytochemical and immunologic (cell suspension) methods. Leu-M1 was positive in all the AML and in half of the ALL cases. These results suggest that Leu-M1 does not allow differentiation between AML and ALL. For the ALL cases Leu-M1 was positive in 15/28 B-cell types, 4/12 T-cell type and 3/4 'null'-cell type cases. Thus, this antibody is of no assistance in defining types B, T, or 'null' in ALL. Leu-M1 was also studied on paraffin sections of 34 high grade malignant lymphomas. The antibody was negative in all 13 B-cell lymphomas (lymphoblastic: 6; immunoblastic: 7) and in all 4 'null' cell lymphomas. It was positive in 4/9 peripheral T-cell type, the other T-cell lymphomas (lymphoblastic: 5; immunoblastic: 3) remaining negative. Thus, Leu-M1 may be positive in T-cell lymphomas but it is negative in B-cell lymphomas and is always negative in B or T lymphoblastic types. It seems that lymphoblasts are Leu-M1 negative in non-Hodgkin's lymphoma and may be Leu-M1 positive in leukaemias.     

The proportion of abnormal karyotypes in acute leukemia samples related to method of preparation

Bone marrow and peripheral blood were studied from 200 patients with acute leukemia [109 with acute myeloid leukemia (AML), 91 with acute lymphoblastic leukemia (ALL)] who had samples cultured for varying times and who had a mixture of chromosomally abnormal and normal cells. The mean percentage of abnormal metaphase cells increased with culture time. The peak was reached at 48 hours and declined slightly after 72 hours in culture for ALL patients. The mean percentage of abnormal cells increased up to 72 hours in culture for AML patients. In 68 patients (31 AML and 37 ALL), cytogenetic data were available from samples processed with both direct preparations and culture methods. The percentage of abnormal cells increased after culture in 49 patients (23 AML and 26 ALL), while it decreased or remained at the same level in 19 patients. For AML patients, the mean percentage of abnormal cells was significantly different between direct (38%) and cultured preparations (63%), (p less than 0.001). Seven of 9 patients with AML who showed a greater than 50% increase in abnormal cells after culture had either a t(8;21), t(15;17), or abnormalities involving 11q23. The two patients who showed a significant decrease in abnormal cells both had a translocation involving 11q13. Compared with ALL, more AML patients showed greater than 80% abnormal bone marrow metaphase cells at diagnosis or at relapse.     

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.     

Combination assay of IAP and ADA in hematologic malignancies

We measured the levels of adenosine deaminase (ADA) and immunosuppressive acid protein (IAP) in 10 patients with acute myeloid leukemia (AML), 5 with acute lymphoblastic leukemia (ALL), 8 with chronic myeloid leukemia (CML), 7 with myelodysplastic syndrome (MDS), 5 with malignant lymphoma (ML), 3 with multiple myeloma (MM) and one with adult T cell leukemia. On admission, the level of IAP was abnormally high in all cases of AML and ALL 50% of CML cases, 71.4% of MDS cases, 60% of ML cases and none of MM cases. ADA was elevated in all cases of ALL, 77.8% of AML and CML cases, 57.1% of MDS cases, 60% of ML cases and 33.3% of MM cases. In 7 patients with AML, the level of IAP returned to normal when they achieved complete remission. On the other hand, the level of ADA had already returned to normal even during induction therapy. ADA showed a positive correlation with the absolute number of peripheral blasts and lactic dehydrogenase both in AML and ALL. These results suggest that ADA indicates the activity of leukemia and IAP indicates the immunocompetence of the host.     

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.     

Effects of IL-7 on human lymphocytes.

Interleukin-7 (IL-7) is known as a growth factor for pre B-cell and mature T-cells in human. But in leukemic cells, IL-7 effect is variously reported. To investigate the effect of IL-7 on the cells of childhood acute leukemia we used 3H-Thymidine assay. Twelve Acute lymphoblastic leukemia (ALL), seven T-ALL and three Acute myelogenous leukemia (AML) were involved in this study. Two out of twelve ALL and three out of seven T-ALL bone marrow (BM) cells were stimulated by IL-7 in 3H-Thymidine incorporation. In normal and AML BM cells, IL-7 had no stimulatory activity as in various leukemic cell lines. Two normal peripheral blood T-cells responded to IL-7 dose dependently. We have seen the effect of IL-7 to stimulate T-lineage cells but, for precise conclusion, further study using more purified samples will be needed.     

Utility of white blood cell suspect flags and histogram pattern in the detection of acute leukemia by Advia-60 automated hematology analyzer

Blood samples from patients with acute leukemia, when analyzed with automated hematology counters, tend to introduce inaccuracies in the automated differential count and can cause diagnostic confusion without providing definite clues to the presence of abnormal cells. We designed this study to assess the utility of white blood cell (WBC) flags and histogram pattern generated by Advia-60 automated hematology analyzer in the recognition and categorization of acute leukemia. Data printouts of 31 newly diagnosed cases of acute leukemia, 22 with acute myeloid leukemia (AML) and 9 with acute lymphoblastic leukemia (ALL) were reviewed. All cases of AML and ALL generated the WBC suspect blastflag M2 associated with two of the non blast suspectflags G1 and G2. Among the cases of AML, 95.5% of the WBC histogram patterns were definitive of the presence of abnormal cells and were indicative of the myeloid nature of cells. Only 44.4% of the histograms in the cases of ALL could be definitive of the presence of abnormal cells and 33.3% were indicative of their lymphoid nature. Significantly, 55.5% of the histograms in ALL were normal. The false positives for both AML and ALL were 10.5% when only WBC flagging was considered and were reduced to 0.05% when the flags were combined with histogram patterns for interpretation. Combined flagging and histogram recognition can be of aid in identifying cases of acute leukemia and the morphologist can then assess these samples further. This ensures that cases of acute leukemia, especially in high output laboratories, are not inadvertently missed.     

Characterization of HLA-DR antigens on leukaemic cells.

A large series of leukaemias (1,512 cases) and leukaemic cell lines (40) have been tested for selective expression of a monomorphic HLR-DR determinant using a monoclonal antibody (DA2). Relatively mature myeloid leukaemias (APML, CGL) and erythroid leukemias are DR-, in contrast to most (72% leukaemias of myeloid precursors (e.g. AML) which are DR+. Non-T ALL are DR+ but T (thymic) ALL are invariably DR-. In contrast to the latter, some leukaemias with mature T cell phenotypes are DR+. Leukaemias or lymphomas of B cells and B cell precursors (e.g. pre-BALL) are invariably DR+, whereas myeloma or plasma cell leukaemias are DR-. This pattern of selective expression appears to closely parallel that seen in normal haemopoietic differentiation. Biochemical features of HLA-DR structures on leukaemic cells have been compared with the known features of B cell derived DR molecules and in one case ALL compared with an autologous (EBV transformed) B cell line. Most leukemic cells showed the same general alpha and beta two chain structure. However, B cell line and most chronic leukaemias showed the presence of an extra band of molecular weight 30,000 daltons (p30) with an intermediate electrophoretic mobility on SDS-PAGE between that of the alpha and beta DR chains. In acute leukaemias and leukaemic cell lines (i.e. immature cells) p30 was not seen unless short labelling times were used. Two dimensional NEPHGE/SDS-PAGE under appropriate labelling conditions showed that the pattern of spots obtained from an ALL line (Nalm-6) and its autologous EBV transformed partner (B85) were similar though not identical. Pulse chase labelling of Nalm-6 and B85 showed that the turnover rate of p30 relative to DR alpha and beta chains, differed in the two lines.     

Anti-CD10 immunoperoxidase staining of paraffin-embedded acute leukemias: comparison with flow cytometric immunophenotyping

CD10 is common in B-precursor acute lymphoblastic leukemia (ALL) but is rare in acute myeloid leukemia (AML). However, until recently, analysis for CD10 has generally required fresh or frozen tissue. 56C6 is a monoclonal antibody that is now commercially available for the detection of CD10 in routinely processed paraffin-embedded tissue. Immunoperoxidase stains for CD10 on paraffin-embedded bone marrow core biopsy specimens (B5-fixed, decalcified) and marrow aspirate clots (formalin-fixed) were compared with flow cytometric immunophenotyping for CD10 on fresh cell suspensions in 20 cases of AML and in 30 cases of ALL. CD10 detection by immunohistochemistry agreed with CD10 by flow cytometry in 98% (49 of 50) of acute leukemias. The results matched in 100% (20 of 20) of AML. Five percent (1 of 20) of AMLs expressed CD10. Two of the AMLs with monocytoid differentiation were interpreted as negative for CD10 by flow cytometry, although these had nonspecific dim immunofluorescence for multiple markers, including CD10, and these cases were negative by immunohistochemistry. CD10 detection by immunohistochemistry agreed with CD10 by flow cytometry in 97% (29 of 30) of ALL. Eighty-four percent (21 of 25) of B-precursor ALL and 40% (2/5) of T-lineage ALL expressed CD10 by immunohistochemistry. In 1 case of B-precursor ALL, CD10 was dimly positive in 24% of the blasts by flow cytometry but negative by immunohistochemistry. We conclude that immunohistochemical staining of paraffin-embedded tissue, either B5- or formalin-fixed, is an effective method for the detection of CD10 in acute leukemia. This technique is useful in distinguishing AML from ALL.     

Translocations involving 12p in acute myeloid leukemia: Association with prior myelodysplasia and exposure to mutagenic agents

Six cases of acute myeloid leukemia (AML) with translocations involving 12p are described. The patients were one child age 7 yrs and five adults with an age range of 20–66 yrs (median 46 yrs). In two patients AML followed treatment for acute lymphoblastic leukemia (ALL), in one case after 11 years disease-free survival. Of the remaining four patients, two had been occupationally exposed to possible mutagens and three had a previous myelodysplastic phase. Two patients achieved complete remission; survival for the six cases was between 1 and 24 months (median 6.5 months). The breakpoints in 12p occurred in p11, p12, and p13, indicating that several sites are important in these rearrangements, and it is suggested that t(12; 17)(p 11;q11) is a new nonrandom abnormality in AML.     

Detection of terminal deoxynucleotidyl transferase in acute leukemias using monoclonal antibodies directed against native and denatured sites

Monoclonal antibodies (MoAb) directed against human terminal deoxynucleotidyl transferase (TdT) have been developed recently. The authors evaluated the reactivity of two TdT MoAb, one directed against a native site and the other against a denatured site, in bone marrow samples from patients with acute lymphoblastic leukemia (ALL) and acute myelogenous leukemia (AML). Results were correlated with the immunophenotype and compared with those obtained with an anti-TdT polyclonal antibody (PoAb). The authors found that 39 of the 45 children (87%) with ALL were positive with the anti-TdT PoAb, while only 25 of 45 (56%) were positive using MoAb. In the 41 of 45 cases of ALL for which marker studies were available, there was no relationship between immunophenotype and reactivity with the PoAb or either MoAb. Five cases of AML were studied and two were positive using the PoAb, but none showed staining with the MoAb. The authors' findings demonstrate that, although MoAb may be used to detect TdT in acute leukemia, the two MoAb used do not correlate with immunophenotype and are less sensitive than the PoAb. However, the MoAb appears to demonstrate more specificity for ALL than the PoAb, since it was not reactive in PoAb+ AML.