Receptors for sheep erythrocytes (E) and erythrocyte-antibody-complement complexes (EAC) on the lymphoblasts of childhood acute lymphoblastic leukemia

Two cell-surface markers, rosette formation with sheep erythrocytes (E-rosette) as a T-cell marker and rosette formation with bovine erythrocyte-antibody-complement complex (EAC-rosette) as a B-cell marker were determined on peripheral blood lymphocytes and lymphoblasts from normal and 89 children with acute lymphoblastic leukemia (ALL). In the majority of the patients (12/15 untreated patients and 6/11 patients in relapse), lymphoblasts exhibited neither E- nor EAC-rosette formation. Lymphoblasts from one untreated patient with mediastinal mass displayed E-(50%) and EAC-rosette formation (15%). In 3 of 11 patients in relapse, lymphoblasts displayed an increase in EAC-rosette formation with progressive disease. In the remaining patients with active disease, a small and variable proportion of lymphoblasts expressed E and/or EAC-rosette formation. In 63 patients in remission, percentages of E- and/or EAC-rosette were similar (p > 0.05) to those of control. The results indicate a wide heterogeneity with respect to expression of lymphocyte membrane markers in lymphoblasts and in normal lymphocytes in patients with active ALL.     

Nucleoside phosphorylase activity in normal and leukemic cells

Nucleoside phosphorylase (NP) activity was assayed in normal peripheral blood lymphocytes, mature and immature thymocytes fractionated by peanut agglutinability, CLL lymphocytes, and ALL lymphoblasts to determine applicability as an enzymatic cell marker. Circulating lymphocytes had the highest activity, immature thymocytes the lowest, and mature thymocytes were intermediate in NP level. This suggests an increase in NP activity with T-cell maturation. CLL lymphocytes showed very low activity, confirming previous reports. However, the NP activity of the lymphoblasts of 40 patients with B, T, and non-B, non-T ALL was similar to that of normal peripheral blood lymphocytes and could not be used to discriminate between these subgroups of ALL.     

Carcinoembryonic antigen (CEA), alphafetoprotein (AFP) alpha and beta subunits of human chorionic gonadotropin (hCG) in cerebrospinal fluid of children with acute lymphoblastic leukaemia

The cerebrospinal fluid (CSF) and plasma levels of CEA, AFP, alpha and beta hCG were determined by radioimmunoassay in 19 children with acute lymphoblastic leukaemia (ALL). CSF in 15 patients at the onset of ALL was examined in the first week after diagnosis and subsequently every two months. In 4 other children in second complete remission of ALL, CSF was examined every two months as well. Elevated values of CEACSF were present in 1/15 patients at the onset of ALL, of AFPCSF 0/15, alpha hCGCSF in 2/15, beta hCGCSF in 2/15 cases. The elevated levels of these markers in CSF became normal in successive lumbar punctures and none of these children developed central nervous system (CNS) relapse in further follow-up. Isolated CNS relapses were diagnosed 13 times in 7 children. Elevated CEACSF levels were found in 6/13 cases (maximum, 25.0 ng/ml) and in one patient CEACSF levels correlated well with pleocytosis. Elevated AFPCSF values were present in 0/13 cases, alpha hCGCSF in 0/13 and beta hCGCSF in 3/13 patients and became normal by the next CSF examination. The determination of CEA, AFP, alpha and beta hCG in plasma did not play a role in monitoring CNS relapse in ALL patients.     

儿童急性淋巴细胞白血病及阿霉素所致Jurkat细胞凋亡时WAVE1表达研究

目的：初步探讨WASP家族Verprolin同源蛋白1（WAVE1）在急性淋巴细胞白血病（ALL）发病中可能的作用及意义。方法：运用逆转录-聚合酶链反应（RT-PCR）半定量法和蛋白质印迹（Western blotting）分别检测40例ALL初治患儿、15例化疗完全缓解半年、4例复发、10例非白血病患儿BMMCs中WAVE1 mRNA和蛋白的表达水平。以不同浓度阿霉素处理Jurkat细胞：①采用MTT法测细胞增殖;②采用流式细胞仪检测细胞凋亡率;③采用RT-PCR和Western blotting检测WAVE1表达。结果：ALL初治和复发患儿BMMCs均有WAVE1 mRNA和蛋白的表达,对照和缓解组BMMCs中mRNA和蛋白低表达或无表达,初治和复发组的WAVE1 mRNA和蛋白的表达表达水平显著高于化疗后缓解组和对照组（P<0.01）。阿霉素明显抑制Jurkat细胞增殖,抑制作用呈剂量时间依赖效应（P<0.05）;阿霉素作用24 h后,细胞凋亡随药物浓度增增高而增加,与对照组相比,差异有显著性(P<0.05);细胞WAVE1 mRNA和蛋白表达水平随阿霉素处理浓度的增高而降低,与对照组比较,差异有显著性(P<0.05)。结论：WAVE1在ALL患儿BMMCs中高表达;WAVE1可能与儿童ALL病程相关,它可能成为动态检测儿童ALL病情的一个新指标。     

Eosinophilic Meningitis Preceding Meningeal Relapse in a Child with Acute Lymphoblastic Leukemia: Abnormal Nucleotide Content of Eosinophils

A case of eosinophilk meningitis 2 months before the appearance of lymphoblasts in the cerebrospinal fluid is described in a child with acute lymphoblastic leukemia (ALL). The peripheral blood showed no simultaneous eosinophilia. The child was successfully treated for her CNS relapse, and complete remission was easily obtained. The eosinophils and lymphoblasts disappeared quickly after the administration of intrathecal methotrexate. However, 3¹/₂ years later hypereosinophilia developed in the blood and bone marrow, heralding bone marrow relapse. Simultaneously, meningeal relapse was diagnosed and this time the cerebrospinal fluid showed a mixture of lymphoblasts and eosinophils. Treatment was reinstituted and complete remission was again obtained. Analysis of the blood eosinophils showed abnormal nucleotide patterns. Similar patterns were previously found in the lymphoblasts from other ALL patients.     

Leukemic cell differentiation in childhood leukemias. Analysis by enzyme markers

Enzyme marker analysis has become a valuable tool in leukemia research, especially as a part of the so-called multiple marker analysis which combines several disciplines for characterization of leukemia cells. In this study the qualitative activities of three enzyme markers were determined in leukemic cells from pediatric patients with acute leukemias: acid phosphatase (E.C. 3.1.3.2), carboxylic esterase (E.C. 3.1.1.1) and hexosaminidase (E.C. 3.2.1.30). The leukemia subtypes displayed different types of isoenzyme patterns. No additional isoenzyme was found that was not observed in normal blood cells, nor a single isoenzyme specific for a leukemia subtype.The biochemical profiles illustrated the existence of subsets in cALL, T-ALL and AML.The enzymologic polymorphism and the immunologic heterogeneity seen in leukemia subclasses have led together to an extended classification scheme of leukemias as well as to model schemes of normal hematopoietic cell differentiation. Despite former and constantly published assumptions there are still no specific markers of leukemia cells.Abbreviations acP I-V groups of acid phosphatase isoenzymes, migrating in electrophoresis as a single band, split by IEF into several isoenzymes - ALL acute lymphocytic leukemia - AML acute myelocytic leukemia - AMML acute myelomonocytic leukemia - AUL acute undifferentiated leukemia - B-ALL B-cell-derived acute lymphocytic leukemia - cALL common ALL, ALL with the common phenotype (cALL-A+) - cALL-A common ALL-antigen - c/T-ALL ALL subgroup with blast cells of an intermediate phenotype expressing both—cALL- and T-antigens (cALL-A+, T-Ag+) - Dr antigens coded by the histocompatibility locus D - E sheep-erythrocyte rosette receptor - Est L, M.T.U. Bu groups of esterase isoenzymes, migrating in electrophoresis as a single band, splitted by IEF into several isoenzymes - Hex A form of -hexosaminidase with an acidic isoelectric point - Hex B form with a basic isoelectric point - Hex C electrophoretically more anodic form than form A - Hex I intermediate form, localized between the A and B form - IEF isoelectric focusing - Null-ALL ALL with no detectable immunologic surface marker - pre T-ALL form of ALL with lymphblasts expressing only T-cell antigens (T-Ag+) without an E-receptor (E-) - SmIg surface immunoglobulin - T-Ag T-cell antigen - T-ALL Thymus-derived acute lymphocytic leukemia     

Changes in the vertebrae as an initial symptom of leukemia

Back pain due to vertebral changes as early feature of acute lymphocytic leukemia (ALL) in childhood has been infrequently reported. There are 8 previously described patients with similar clinical and laboratory data, suggesting a biologically unique subset of ALL. Characteristic findings of this rare primary manifestation of leukemia are lack of significant organomegaly or lymphadenopathy, normal or low white blood cell count with predominance of lymphocytes and rarely circulating lymphoblasts, normal platelet count, uric acid and lactate dehydrogenase values. In the following report we make a further attempt to confirm the hypothesis of a subset of ALL, demonstrating two additional patients with characteristic features of ALL presenting with vertebral changes and low leukemic burden.     

Minimal requirements for the diagnosis, classification, and evaluation of the treatment of childhood acute lymphoblastic leukemia (ALL) in the "BFM Family" Cooperative Group.

Minimal requirements and their rationale for the diagnosis and the response to treatment in childhood acute lymphoblastic leukemia (ALL) were defined in the recently instituted "BFM-Family"-Group, in which the German, Austrian, Dutch, Italian, Belgian, French and Hungarian childhood leukemia study groups cooperate. ALL is defined as > or = 25% lymphoblasts in the bone marrow; for confirmation of the diagnosis and classification the criteria of the French-American-British (FAB) criteria are retained. For determination of the extent of the disease at diagnosis or relapse the criteria by the Rome Workshop [1986] are recommended: An obligatory panel of monoclonal antibodies for immunophenotyping was defined, as well as criteria for precursor B-ALL and T-ALL. Cytogenetic studies may support the diagnosis and subtyping, and are essential to identify certain patients with a high risk of treatment failure (f.i. t(9;22), t(4;11)). The role of molecular genetics for the diagnosis and the characterization of leukemia and the value of its clinical application needs further elucidation. Relapse was defined as recurrence of evident leukemia in the blood, bone marrow (> or = 25% lymphoblasts) or at any other site (to be confirmed by histological examination). Bone marrow involvement combined with extramedullary relapse was defined as > or = 5% lymphoblasts in the bone marrow.     

Minimal requirements for the diagnosis,classification, and evaluation of the treatment of childhood acute lymphoblastic leukemia (ALL) in the “BFM family” cooperative group

Minimal requirements and their rationale for the diagnosis and the response to treatment in childhood acute lymphoblastic leukemia (ALL) were defined in the recently instituted “BFM-Family”-Group, in which the German, Austrian, Dutch, Italian, Belgian, French and Hungarian childhood leukemia study groups cooperate. ALL is defined as ≥ 25% lymphoblasts in the bone marrow; for confirmation of the diagnosis and classification the criteria of the French-American-British (FAB) criteria are retained. For determination of the extent of the disease at diagnosis or relapse the criteria by the Rome Workshop [1986] are recommended: An obligatory panel of monoclonal antibodies for immunophenotyping was defined, as well as criteria for precursor B-ALL and T-ALL. Cytogenetic studies may support the diagnosis and subtyping, and are essential to identify certain patients with a high risk of treatment failure (f.i. t(9;22), t(4;11)). The role of molecular genetics for the diagnosis and the characterization of leukemia and the value of its clinical application needs further elucidation. Relapse was defined as recurrence of evident leukemia in the blood, bone marrow (≥ 25% lymphoblasts) or at any other site (to be confirmed by histological examination). Bone marrow involvement combined with extramedullary relapse was defined as ≥ 5% lymphoblasts in the bone marrow. © 1992 Wiley-Liss, Inc.     

Abnormal lymphocyte function in childhood leukemia

Lymphocyte function was evaluated in 26 untreated children with acute lymphoblastic leukemia (ALL) and 5 patients with acute myelogenous leukemia (AML) by stimulation with phytohemagglutinin (PHA) in dose- and time-response studies. The response to PHA correlated positively with the percentage of lymphocytes (r = + 0.786) and negatively with the percentage of lymphoblasts (r = ? 0.728). Sixteen patients with a WBC < 20,000/cu mm (51 ± 5% lymphocytes, 28 ± 7% lymphoblasts, and 39 ± 20% T cells) responded normally (81,156 ± 8,229 cpm) on the fourth or fifth day of culture. Ten patients with a WBC > 20,000/cu mm (10 ± 3% lymphocytes, 88 ± 4% lymphoblasts and 18 ± 28% T cells) had a significantly lower response to PHA on these days (13,609 ± 5,568 cpm). Six of the ten high-WBC patients had a delayed peak response on the sixth or seventh day of culture. This abnormal response to PHA is similar to that which has been described in patients with chronic lymphatic leukemia and is at least partially due to the dilution of a normal lymphocyte population by the proliferation of a population of non-PHA-responsive lymphoblasts. The remaining four high-WBC patients had flat PHA dose- and time-response curves and a poorer clinical course. Two of them had T-cell leukemia. The absence of response to PHA in these children may characterize a group of patients with acute lymphoblastic leukemia who are immunodeficient at the time of diagnosis and may reflect the presence of a unique population of lymphoblasts with suppressor activity.     

Aplastic presentation of acute lymphoblastic leukemia: evidence for cellular inhibition of normal hematopoietic progenitors

Childhood acute lymphoblastic leukemia (ALL) may rarely present with blood and bone marrow findings suggestive of aplastic anemia. Although numerous examples of ALL presenting with this phenomenon have been reported, there is no accepted explanation for the pathogenesis of this preleukemic hypoplasia. We report a case of a child with ALL whose initial presentation was characterized by pancytopenia and bone marrow hypoplasia and who had repeated episodes of pancytopenia at times of systemic relapse. In vitro coculture experiments demonstrated that the leukemic cells from this patient were inhibitory for the growth of myeloid, erythroid, and megakaryocytic progenitor cells from normal peripheral blood. This inhibitory effect exhibited a dose-dependent relationship with the number of added lymphoblasts and persisted when the lymphoblasts were irradiated to prevent leukemic cell growth. Inhibitory activity was not present in media conditioned by the growth of the patient's lymphoblasts, nor was it present in lymphoblasts from three other children with ALL with similar immunophenotype but without marrow aplasia. These data suggest that the aplastic presentation of ALL may be attributable to inhibitory properties intrinsic to the leukemic cells rather than to other host factors.     

Ratio of methotrexate to folate uptake by lymphoblasts in children with B-lineage acute lymphoblastic leukemia: a pilot study

PURPOSE: Methotrexate (MTX) remains one of the most effective drugs for the treatment of children with acute lymphoblastic leukemia (ALL). Because MTX and 5-methyltetrahydrofolate (5CH3THF) share uptake and metabolic pathways, the efficacy of MTX is likely to depend not only on its metabolism but also on how well folate is accumulated by lymphoblasts. The authors' goal was to compare in vitro folate and antifolate uptake in B-lineage lymphoblasts from patients who remained in continuous complete remission (CCR) and those in whom relapse occurred. PATIENTS AND METHODS: Twenty-four children with B-lineage ALL were studied at diagnosis (n = 20) or relapse (n = 4). Lymphoblasts obtained by bone marrow aspiration were incubated for 24 hours in vitro with 0.05 microM 5CH3[3H]THF or 1 microM [3H]MTX. RESULTS: As of July 1999, 16 patients studied at diagnosis remained in CCR at a median follow-up of 45 months after achieving remission. Two of the patients studied at relapse are in second CCR; the remaining two died from progressive disease. The median uptake of neither [3H]MTX nor 5CH3[3H]THF differed significantly between the 16 patients in first CCR studied at diagnosis and the 4 patients studied at relapse. However, the median ratio of [3H]MTX:5CH3[3H]THF uptake differed significantly for patients who remained in first CCR versus patients studied at relapse. CONCLUSIONS: The uptake of [3H]MTX in relation to 5CH3[3H]THF by leukemic lymphoblasts in vitro may correlate positively with treatment outcome in children with B-lineage ALL. A larger study of homogeneously treated patients is necessary to confirm these results.     

Relapse in childhood acute lymphoblastic leukemia after elective cessation of initial treatment: Failure of subsequent treatment with cyclophosphamide,cytosine arabinoside,vincristine and prednisone (COAP)

Although the majority of children with acute lymphoblastic leukemia (ALL) can electively stop treatment after 21/2–5 years of continuous disease-free remission, 20–25% of those patients relapse after discontinuation of therapy. We treated 15 patients whose disease recurred after stopping treatment. Fourteen of them attained complete remission, but the median duration of disease-free survival was only 11 months. In this population, the site of initial relapse, bone marrow or testicle, did not influence subsequent outcome. Patients who relapsed within six months of stopping initial therapy had shorter second remissions than those who relapsed after six months. We conclude that the combination chemotherapy utilized in this study was inadequte for the control of relapsed ALL. Future programs will have to use different drug combinations or bone marrow transplantation.     

Bone relapse in acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) can occasionally relapse in unusual extramedullary sites like bone. Here we present a 6.5-year old boy with T cell ALL who developed a swelling in left tibia which was infiltrated with lymphoblasts 7 months after completion of chemotherapy. Bone marrow and cerebrospinal fluid were negative for blasts. This is the first reported case of bone relapse in ALL from India. We discuss the previous cases of isolated bone relapse in ALL reported in English literature     

Cell markers in lymphoma syndrome leukemia in children: a pilot study

Children with acute lymphocytic leukemia (ALL) who have a "lymphoma syndrome" (LySLk) defined by the presence of at least three of the following criteria: a) Hg greater than 10 g/dl, b( lymph nodes greater than 3 cm, c) spleen below umbilicus, d) liver below umbilicus, and e) mediastinal mass, appear to represent a subgroup of ALL. These children have a poor prognosis for survival when treated with standard chemotherapy for ALL. We performed a retrospective review of 21 patients at Children's Memorial Hospital with LySLk diagnosed from Jan 24, 1977 to July 8, 1981 and of the surface markers on their leukemic cells at diagnosis. Surface markers identified included E-rosettes (E), surface immunoglobulin (Slg), and common ALL antigen (cALLA). Four patients were cALLA positive and E-rosette negative; nine patients were E-negative, cALLA negative; six patients were E positive, cALLA negative. In two patients E-rosettes could not be accurately determined because of a low percentage of lymphoblasts in the samples studied. Follow-up data on cALLA-positive and cALLA-negative patients revealed 4/4 cALLA-positive patients with no evidence of disease (NED) at 22 + to 45 + months from diagnosis and 2/16 cALLA-negative patients NED at 19 + and 57 + months. Thus it appears that the majority of children with LySLk have lymphoblasts which are cALLA negative. Patients who meet clinical criteria for LySLk but whose surface markers are E negative, cALLA positive may have a better prognosis and may represent a separate subgroup of patients with ALL and, therefore, should be given therapy appropriate for their prognostic classification by more standard criteria, such as white blood count, age, and sex.     

Chemotherapy with cyclophosphamide,vincristine, cytosine arabinoside,and prednisone (COAP) in childhood acute lymphoblastic leukemia (ALL)

Three groups of children with acute lymphoblastic leukemia (ALL) were treated with intermittent cyclophosphamide, vincristine, cytosine arabinoside, and prednisone (COAP). Group A (no prior relapse) and Group B (prior single-agent relapse) received COAP after 12 months on another chemotherapy regimen. Children in Group C (prior relapse on multiagent regimens) received COAP following A-COAP (asparaginase plus COAP) reinduction. Median disease-free survival after beginning COAP was not reached for Group A, but was only 7 months for Groups B and C. As of November 1976, there were 8 of 15 Group A patients, 1 of 12 Group B patients, and 1 of 28 Group C patients who had remained disease-free from 38 to 60 (median 54.5) months and were off chemotherapy. COAP has activity in childhood ALL. However, effectiveness in markedly diminished in patients with prior bone marrow relapse.     

Value of Routine Bone Marrow Examination for Detection of Bone Marrow Relapse in Children with Standard Risk Acute Lymphoblastic Leukemia

The value of routine bone marrow examination (RBME) in children during and after treatment for standard risk acute lymphoblastic leukemia (SR-ALL) was Investigated. The clinical symptoms and peripheral blood findings at the time of bone marrow relapse of 28 children were reviewed and compared with those of 28 matched controls in continuous complete remission. Five (45%) children with bone marrow relapse during maintenance therapy and six (35%) after cessation of cytostatic treatment were asymptomatic at the time of relapse. Signs indicative of relapse duriny treatment were lymphoblast cells in the peripheral blood, thromhocytopenia, hepatomegaly, anemia, or leukopenia in decreasing order of frequency. Afer cessation of treatment these signs were lymphoblasts in the peripheral blood, hepatomegab, splenomegaly, thrombocytopenia, or leukocytosis. Except for one case with thrombocytopenia, no signs suspicious for relapse were found in the control groups. When each sign was evaluated separately only the presence of lymphoblasts in peripheral blood and hepatomegaly were significant symptoms for relapse after cessation of treatment. The mean percentage of lymphoblasts in the bone marrow at the time of relapse was significant& lower for patients with an unpredicted relapse (46.8%) than patients with clinical and/or laboratory evidence of relapse (79.5 %). When lymphoblasts were present in the peripheral blood the percentage of lymphoblasts in the bone marrow was always more than 40%, both during and after cessation of treatment. These data suggest a relation between clinical and laboratory symptom and progression of the disease. It is concluded that 467% of relapses are detected by RBME in the absence of clinical or laboratory symptoms. This early detection may have a positive prognostic influence with more effective treatment for relapsed ALL.     

Cytokinetic studies in children with untreated acute lymphocytic leukaemia (ALL): relationship to "T" cell markers.

"The labelling index (LI), mitotic index (MI) of marrow lymphoblasts and the percent of peripheral blood lymphocytes and lymphoblasts that form rosettes with sheep red cells at 4 degrees C ("T4"), were measured at presentation in 33 children with ALL. There was a significant correlation between LI and MI, but no significant correlations between them and the total white cell count at diagnosis or the "T4" percent. Three patients had greater than 55% "T4" rosettes and showed increased LI and MI, and 2 have relapsed; 12 had less than 20% "T4" rosettes, showed an increased LI (LI greater than 8% in 8 of 12) but not MI, and 5 have relapsed; 18 had 20--55% "T4" rosettes and generally had the lowest LI (LI less than 8% in 11 of 18), and only 3 have relapsed. Our findings suggest that patients with high and low percentage of "T4" rosettes in the peripheral blood have an increased fraction of leukaemic cells in DNA synthesis and have a diminished chance of prolonged remission.     

Methylation pattern of calcitonin (CALCA) gene in pediatric acute leukemia

Disruption of deoxyribonucleic acid (DNA) methylation patterns has emerged as one of the possible origins of leukemogenesis. Calcitonin (CALCA) gene is a hot-spot for gene hypermethylation in acute leukemias. This study aimed to systematically analyze the methylation status of CALCA gene in pediatric acute leukemia using methylation-specific polymerase chain reaction (MSP) and assess its value as a potential prognostic biomarker. The study population consisted of 70 children divided into; 35 acute myeloblastic leukemia (AML) and 35 acute lymphoblastic leukemia (ALL) patients. CALCA gene was found to be hypermethylated in 54.3% of AML and 65.7% of ALL patients. CALCA hypermethylation was neither correlated to any of the clinicopathologic characteristics of patients, standard prognostic factors nor response to induction therapy (P>0.05). Hypermethylated AML and ALL patients displayed poorer clinical outcome when compared with hypomethylated counterparts as evidenced by high relapse and mortality rates with the occurrence of early relapse (P<0.05). The estimated overall and disease-free survival rates at 2.5-years were significantly shorter for hypermethylated patients in both groups (P<0.01). Our results suggest that CALCA gene methylation pattern is an independent prognostic factor in pediatric acute leukemia that could characterize a group of patients with enhanced risk of relapse and death.     

Lymphocytic leukemia in children: prognostic significance of clinical and laboratory findings at time of diagnosis.

Forty-eight children with untreated acute lymphocytic leukemia were evaluated with regard to their clinical presentation and the surface membrane characteristics, mitogen responsiveness, and cytochemical staining features of their lymphoblasts. The presence at diagnosis of 20% or more bone marrow lymphoblasts possessing T-cell surface markers was associated with the development of early relapse and death. Age, sex, initial peripheral leukocyte count (WBC), lymph node enlargement or the presence of hepato- or splenomegaly bore no statistically significant relationship to the patient's lymphoblast type, and only a WBC in excess of 10(5)/microliter correlated with a poor prognosis. Leukemic T-cells were found to be periodic acid-Schiff negative from nearly all patients, helping to distinguish such patients from the larger group of children whose leukemic cells were PAS positive, but negative for T-cell membrane features. In those patients who had multiple relapses, the surface membrane characteristics, staining features, and mitogen responses of their lymphoblasts remained constant. This suggests that relapse occurs in the same clone of malignant cells present at diagnosis and that the above features may be reliably used to evaluate and classify patients beyond the time of diagnosis.