Successful carboxypeptidase G2 rescue in delayed methotrexate elimination due to renal failure

We report on an 18.5-year-old woman with osteosarcoma and delayed methotrexate (MTX) elimination due to renal failure after high-dose MTX, in whom rescue with high doses of folinic acid caused intolerable side effects. In this life-threatening clinical situation, the patients was rescued by the administration of recombinant carboxypeptidase G2, a bacterial enzyme that rapidly hydrolyzes MTX into inactive metabolites. This is the first report on the successful clinical use of this alternative catabolic route for the elimination of MTX.

Use of quantitative polymerase chain reaction to monitor residual disease in chronic myelogenous leukemia during treatment with interferon

Interferon-alpha (IFN-alpha) has become a widely used treatment modality in chronic myelogenous leukemia (CML) and was shown to induce complete hematologic responses in about 70% of the patients. In a minority of cases, complete suppression of the Philadelphia (Ph)-positive clone has been observed by cytogenetic investigation or by Southern blot analysis. In most instances, however, analyses by the highly sensitive two-step polymerase chain reaction (PCR) reveal the presence of residual leukemic cells despite continuous treatment. Since PCR positivity has not been associated with an increased risk of disease recurrence, the monitoring of cells carrying the characteristic BCR/ABL rearrangement by qualitative PCR may not facilitate early identification of patients who are likely to relapse. We have therefore employed a quantitative PCR technique to monitor the BCR/ABL mRNA expression levels during the course of treatment in an attempt to assess the response to IFN-alpha at the molecular level and to provide a basis for early detection of progressive disease. Twenty CML patients who received therapy with IFN-alpha in first chronic phase of the disease were enrolled in the study. In addition, we have monitored two CML patients treated with IFN-alpha for relapse after bone marrow transplantation. Thirteen patients who displayed decreasing, constant or fluctuating levels of BCR/ABL expression during an observation period of up to 4 years (mean 25 months) have remained in hematologic remission. Two patients showed an elevation in the marker gene expression upon discontinuation of treatment, but no further increase in BCR/ABL mRNA has been observed after reinitiation of therapy with IFN, and the patients have remained in hematologic remission. In seven patients, quantitative PCR (Q-PCR) analyses revealed increasing expression of the chimeric gene during treatment with IFN-alpha. In all seven cases, the detection of elevated BCR/ABL transcripts by quantitative PCR preceded signs of hematologic or cytogenetic disease progression by up to 8 months (median 6 months). Our data show that quantitative PCR analysis facilitates the monitoring of the response to IFN-alpha therapy and provides an effective diagnostic tool for the timely detection of recurrent disease. The employment of this technique greatly enhances the diagnostic possibilities in the management of chronic myelogenous leukemia.

Detection of tumour cells in peripheral blood and bone marrow from Ewing tumour patients by RT-PCR

The Ewing family of tumours (ET) is characterised at the cytogenetic level by unique chromosome 22 rearrangements. The breakpoints have been cloned and were shown to fuse the EWS gene on chromosome 22 to one of two closely related ETS proto-oncogenes, FLI-I or ERG, which reside on chromosomes II and 21, respectively. The rearrangement results in the expression of chimaeric transcripts, which can be identified by means of reverse transcriptase-polymerase chain reaction (RT-PCR). We applied this method for the monitoring of ET cells circulating in the peripheral blood or infiltrating the bone marrow. The presence of tumour cells could be detected with a sensitivity of I in I x 10(6) nucleated cells. When samples were kept at 4 degrees C, tumour cells could still be identified after 48 hr of storage. Positive RT-PCR signals originated from intact ET cells rather than from free RNA released by ruptured tumour cells. We analysed peripheral blood, bone marrow samples and peripheral blood stem cell collections from 16 ET patients. At diagnosis, bone marrow specimens collected from 6 patients and I peripheral blood specimen tested positive for EWS chimaeric RNA. During therapy tumour cells were detected in bone marrow aspirations obtained from 2 patients. Our results show that ET cells infiltrating the bone marrow or circulating in peripheral blood can be identified by RT-PCR. The clinical implications for the presence of ET cells in samples detected by RT-PCR at diagnosis and during therapy requires further evaluation.

IL-2 inhibits proliferation of K562 cells and reduces accumulation of bcr/abl mRNA and oncoprotein

Cell lines of myeloid origin have been shown to express interleukin-2 receptors (IL-2R). Here, we demonstrate the expression of IL-2R alpha and IL-R beta on the CML blast cell line K562 by FACS analysis and cross-linking assay. Furthermore, we examined the effect of IL-2 on leukemic progenitor growth, employing K562 as a model. Clonogenic growth was assessed after 3 days of culture by colony formation in a serum-free, semi-solid assay system. IL-2 was found to exhibit a dose-dependent suppressive effect on K562 clonogenicity with 48% inhibition of colony formation at 250 U IL-2 and 60% inhibition at 1000 U IL-2. Philadelphia chromosome (Ph)-positive K562 cells possess multiple copies of the bcr/abl fusion gene whose transcript and protein product (p210) is thought to confer growth advantage to CML cells. We therefore investigated IL-2-dependent modulation of bcr/abl mRNA accumulation and p210 protein levels in K562 cells. After 4 h of culture in the presence of IL-2, a 3-15-fold reduction of bcr/abl mRNA accumulation was demonstrated by competitive reverse PCR. Reduction of bcr/abl fusion protein levels was demonstrated at 24 h of IL-2-supplemented cell culture, employing p210 recognizing monoclonal antibodies (mAbs) in FACS analysis. Levels of proliferation marker Ki67 were only marginally affected. We conclude: (1) K562 cells express both IL-2R alpha and IL-R beta; (2) IL-2 inhibits clonogenic growth of K562 in a dose-dependent manner; and (3) IL-2-mediated inhibition of K562 proliferation is preceded by a reduction of bcr/abl mRNA accumulation and p210 protein levels.

Clinical implications of qualitative and quantitative polymerase chain reaction analysis in the monitoring of patients with chronic myelogenous leukemia. The European Investigators on Chronic Myeloid Leukemia Group

Recent progress in the development of diagnostic techniques has greatly facilitated the monitoring of minimal residual disease (MRD) in patients with hematologic neoplasia. The presence of genetic markers, such as the BCR/ABL rearrangement in chronic myelogenous leukemia (CML), has allowed highly sensitive detection of residual leukemic cells by polymerase chain reaction (PCR). However, complete eradication of the leukemic clone may not be a necessary prerequisite for long-term remission or cure. This observation limits the value of qualitative PCR analysis for prediction of progressive disease and highlights the need to monitor the proliferative activity of the malignant clone in order to permit timely detection of impending relapse. We have developed a quantitative PCR protocol based on the principle of competitive enzymatic amplification and demonstrated its applicability to the monitoring of treatment efficacy and early assessment of clonal expansion in patients with CML. We have introduced the term 'PCR relapse' for the detection of a proliferating leukemic clone by serial quantitative PCR (Q-PCR) analyses. At a recent meeting of the group of European Investigators on Chronic Myelogenous Leukemia (EICML Group) the use of Q-PCR investigation has been recommended for the monitoring of MRD, and the detection of PCR relapse was accepted as a basis for therapeutic decisions. This article discusses problems in the interpretation of MRD by PCR and presents guidelines for the clinical use of qualitative and quantitative PCR analyses.

Detection of numerical and structural chromosome abnormalities in pediatric germ cell tumors by means of interphase cytogenetics

In contrast to the cytogenetically well characterized testicular germ cell tumors (GCT) in adults, reports on cytogenetic studies in pediatric GCT are scarce. The presence of an i(12p) and numerical abnormalities involving chromosome 12 are the most frequent cytogenetic changes in GCT of adults. We have performed in situ hybridization (ISH) studies on paraffin sections and on isolated nuclei of 13 pediatric GCT with particular emphasis on those chromosome abnormalities that are common in adult GCT. These include numerical and structural abnormalities of chromosomes 1 and 12 as well as numerical deviations of chromosomes 8, 10, X, and Y. The histological subsets of the tumors investigated included two dysgerminomas (DGE), one seminoma (SE), two embryonal carcinomas (EC), four mixed and two pure yolk sac tumors (YST), and one undifferentiated (IT) and one differentiated teratoma (TD). Similar to the GCT in adults, additional copies of chromosome 12 were the most frequently observed numerical abnormalities. In contrast to the findings in adult GCT, changes in the size of the pericentromeric hybridization signals of chromosome 12, suggesting the presence of i(12p) chromosomes, were found in only two cases. No chromosome abnormalities were found in the pure TD or in the TD cells of mixed tumors containing a YST component. In the YST portion, however, Ip deletions and/or numerical chromosome changes were present. Surprisingly, deletions of the short arm of chromosome I, del(I)(p36.3), were frequent in pediatric GCT and were the sole abnormality detected in two cases. The Ip36 deletions were present in all stage-IV EC and YST investigated and were absent in the relatively benign TD and in one YST stage-I. Therefore, Ip36 deletions may have value as a prognostic marker in pediatric GCT.

Absence of N-ras mutations in myeloid and lymphoid blast crisis of chronic myeloid leukemia

Mutations within N-ras oncogene codons 12, 13, and 61 occur in approximately 25-30% of patients with acute nonlymphocytic leukemia and at a lower frequency (6-20%) in patients with acute lymphocytic leukemia. Moreover, N-ras mutations have been described in patients with chronic myeloid leukemia (CML) in blast crisis but have not been observed during the chronic phase of the disease. In view of the morphological and clinical similarities between acute leukemia and the blast crisis of CML, the question was raised whether the presence of N-ras mutations is associated with the phenotype of acute leukemia. We investigated leukemic cells from 100 patients with CML for the presence of N-ras mutations in the mutational hot spot codons. The cases analyzed included 87 diagnosed with different types of blast crisis and 13 cases in accelerated or chronic phase of the disease. Fragments from N-ras exons I and II containing the codons of interest were amplified by polymerase chain reaction and analyzed for the presence of point mutations by three different technical approaches, including specific oligonucleotide hybridization, direct sequencing, and single-strand conformation polymorphism analysis. N-ras mutations were not detected in any of the CML patients investigated. Only one patient, in whom the initial diagnosis of CML-blast crisis had been revised to chronic myelomonocytic leukemia, displayed an N-ras mutation within codon 13. Our data strongly suggest that N-ras mutations do not play a role in myeloid or lymphoid blast crisis of CML.

Expression of identical E2A/PBX1 fusion transcripts occurs in both pre-B and early pre-B immunological subtypes of childhood acute lymphoblastic leukemia

The translocation t(1;19)(q23;p13) in pediatric patients with acute lymphoblastic leukemia (ALL) was demonstrated in early reports to result in a consistent fusion between the E2A and PBX1 gene sequences and in the expression of a uniform, chimeric E2A/PBX1 mRNA with transforming potential. More recent observations suggested that cytogenetically identical t(1;19) translocations can result in the transcription of different mRNA species and that expression of the E2A/PBX1 message may be restricted to patients with the t(1;19) who display a pre-B phenotype of ALL. To further assess the correlation between the immunologic subtypes of the disease and specific genetic alterations, we have performed cytogenetic and molecular analyses in 221 children with B-lineage ALL. Expression of the chimeric E2A/PBX1 message was detected in 21 patients. Out of 14 patients, in whom cytoplasmic immunoglobulin (cig) analyses were available, no less than four had a cig- B-cell precursor ALL, whereas 10 displayed a cig+ B-ALL immunophenotype. These findings are at variance with a recent report in which expression of the E2A/PBX1 message was linked exclusively to a subset of patients who displayed a cig+ pre-B-cell precursor phenotype of ALL. In seven cases diagnosed before 1986, cig analyses were not available, and consequently E2A/PBX1 expression could not be correlated to a particular immunological subtype of B-cell precursor ALL. Our results have important implications for the detection of residual disease in pediatric patients where expression of the typical E2A/PBX1 mRNA may occur both in cig+ (pre-B) and cig- (early pre-B) immunologic subtypes of ALL.

Frequent detection of BCR-ABL specific mRNA in patients with chronic myeloid leukemia (CML) following allogeneic and syngeneic bone marrow transplantation (BMT)

We performed a two-step polymerase chain reaction (PCR) to detect bcr-abl-specific mRNA in 440 peripheral blood and/or bone marrow samples of 30 chronic myeloid leukemia (CML) patients (mean 15, range 2-50 samples) following non T-cell-depleted allogeneic (n = 28) or syngeneic (n = 2) bone marrow transplantation (BMT). Median follow-up after BMT is 40 months (range 2-116 months), the median observation time 29 months (range 2-40 months). In 15 patients (50%), bcr-abl-specific mRNA could be detected following BMT. Bcr-abl positivity was rare in patients who were in hematological remission for at least 40 months (2/11). In five patients, PCR positivity was observed only once; all five patients are in complete hematological remission. Ten patients showed bcr-abl specific mRNA in two or more consecutive samples. Hematological relapse occurred in five of the latter patients. Bcr-abl positivity preceded hematological relapse in all cases. Bcr-abl positivity was detected more frequently in patients without graft-versus-host disease (GVHD) (11/15), than in patients with GVHD (4/15) (p < 0.02). Our data indicate that transient bcr-abl positivity is not usually followed by hematological relapse, while patients, who are positive in serial samples have a high risk of relapse.

Acute megakaryocytic leukemia with the t(1;22)(p13;q13)

Acute megakaryocytic leukemia (AMKL) was defined as a new subtype of acute nonlymphocytic leukemia (ANLL) by the French-American-British (FAB) Cooperative Group in 1985. The first consistent chromosomal anomaly described in this subset of ANLL was the translocation t(1;22)(p13;q13) which appears to be restricted to this FAB-subtype (FAB-M7) of AML. To our knowledge, 18 AMKL cases with the t(1;22) have been reported until now in the literature. In all instances, the patients were very young children with only one beyond the infant age (12 months) at the time of diagnosis. Based on the results of two reports in which the frequency of this translocation was assessed, the t(1;22) may be estimated to occur in about 30% of pediatric patients with FAB-ANLL subtype M7. In infants with this subset of ANLL, the t(1;22) seems to be present in the majority (> 65%) of cases. The detection of this nonrandom chromosomal abnormality may therefore provide an additional diagnostic marker in children with AMKL. Herein we review and discuss the clinical and cytogenetic findings in patients with AMKL and the t(1;22).

Early detection of relapse after bone marrow transplantation in patients with chronic myelogenous leukaemia

In patients with chronic myelogenous leukaemia (CML) treated by allogeneic bone marrow transplantation (BMT), detection of residual leukaemic cells carrying the characteristic bcr/abl rearrangement by highly sensitive techniques, such as qualitative polymerase chain reaction (PCR), is of limited value in predicting disease progression. We have therefore adapted the PCR for quantitative assessment of bcr/abl rearranged cells and applied this technique to the monitoring of residual disease in 28 CML patients during up to 106 months of follow-up after BMT. In 5 patients, quantitative PCR revealed increasing amounts of the pathological bcr/abl message, indicating the presence of a proliferating neoplastic clone, and all 5 had a subsequent relapse of disease. By contrast, the remaining 23 patients have been in maintenance-free complete remission for up to 106 months post-BMT. The monitoring by quantitative PCR of residual leukaemic cells during the post-transplant course of CML patients may allow early detection of relapse and provide a rationale for the timely initiation of treatment.

Parental origin of chromosomes involved in the translocation t(9;22)

Functionally equivalent genetic maternal can be labelled by an epigenetic marking process and used differentially depending on whether its origin is maternal or paternal. This phenomenon is known as genomic imprinting and is manifested at either the chromosomal or gene level. Genomic imprinting seems to play an important role in cancer predisposition syndromes, and phenotypic consequences are evident in constitutional deletion syndromes and uniparental disomies. Moreover, there seems to be a preferential retention of paternal alleles in sporadic tumours such as Wilms' tumour, rhabdomyosarcoma, osteosarcoma and retinoblastoma. To investigate whether chromosomes involved in acquired abnormalities of haematologic neoplasms show a similar 'parent of origin' bias, we studied the inheritance of the translocated chromosomes 9 and 22 in cases of Philadelphia-chromosome-positive leukaemia, using unique specific chromosome band polymorphisms. Here we show that the translocated chromosome 9 was of paternal origin, whereas the translocated chromosomes 22 were derived exclusively from the maternal copy, in 11 cases with reliable polymorphisms. Our data therefore provide evidence that imprinting phenomena may play an important role in acquired tumour-specific chromosome rearrangements.

Unexpected heterogeneity in E2A/PBX1 fusion messenger RNA detected by the polymerase chain reaction in pediatric patients with acute lymphoblastic leukemia

The t(1;19)(q23;p13) is the most common recurring chromosomal translocation in childhood acute lymphoblastic leukemia (ALL) and has been associated with adverse prognosis. It involves the rearrangement of two genes, PBX1 and E2A, resulting in the production of transforming chimeric DNA-binding proteins. In all previous reports in which the presence of a chimeric transcript was described, the fusion point between the coding sequences of E2A and PBX1 was found to be constant at the RNA level. We have used RNA-based polymerase chain reaction (PCR) for the detection of E2A/PBX1 messenger RNAs (mRNAs) in children with ALL at the time of diagnosis. Of 21 patients exhibiting this rearrangement, 3 (14%) expressed a variant E2A/PBX1 transcript in addition to the expected one. The relative amounts of the two chimeric mRNAs varied between the patients, but remained constant in the same patient during different stages of the disease. Sequence analysis showed an identical insertion of 27 bp at the E2A/PBX1 junction of the variant RNA species, the translation of which would result in the replacement of Val478 by 10 amino acids. The inserted sequence has not been detected in any other human transcript besides the variant E2A/PBX1 RNA species and probably represents a splicing variant of the chimeric RNA. We conclude that a subset of pediatric patients with ALL that carry the E2A/PBX1 rearrangement express two types of the chimeric mRNA. The biologic significance of this additional E2A/PBX1 transcript is discussed.

The translocation t(1;22)(p13;q13) is a nonrandom marker specifically associated with acute megakaryocytic leukemia in young children

We present the nonrandom occurrence, frequency, and degree of immunophenotype association of the t(1;22)(p13;q13) in children with acute nonlymphocytic leukemia (ANLL). This karyotype anomaly occurred in leukemia cells from five of 445 (1.1%) children with newly diagnosed ANLL who were successfully studied by cytogenetic analysis at four European centers between January 1987 and January 1992. The occurrence of the t(1;22) was restricted to the French-American-British classification (FAB) subtype M7. The overall incidence in children with acute megakaryocytic leukemia (AMKL) was 27.8% (5/18 cases); in infants with AMKL, the frequency of the t(1;22) was 66.7% (4/6 cases). Three of the patients carrying this anomaly had a diploid karyotype, whereas in two cases a hyperdiploid karyotype was found. However, in all five patients, the t(1;22) was the only translocation event present at diagnosis. All patients received aggressive chemotherapy for acute myelogenous leukemia (AML). Two patients died within 15 months of diagnosis without entering remission. One of three patients who entered remission died 7 months after diagnosis, most likely from intramedullar hemorrhage. Only two of the five children with the t(1;22) who received autologous bone marrow transplantation (BMT) are alive and in complete remission (CR) 23 and 40 months after diagnosis, respectively. At the time of diagnosis, the age of the oldest child carrying the t(1;22) was 18 months. The cases with this chromosome anomaly were compared with an age-matched group of five children with AMKL lacking this translocation. The patients with the t(1;22) had a lower median value of the peripheral white blood cell (WBC) count and a higher median hemoglobin level than the patients from the matched group. In the latter cases, normocellular or hypercellular bone marrow (BM) was detected at diagnosis. In contrast, all children with the t(1;22) in our series had a hypocellular BM. Histological BM analyses were available in three of these patients and showed marked fibrosis. Other clinical and laboratory parameters showed no obvious differences between the matched groups. Despite intensive chemotherapy, AMKL in children appears to be associated with a poor prognosis. The clinical courses of the children with AMKL and the t(1;22) presented may be indicative of a beneficial effect of autologous BMT in this subset of patients.

Monitoring of residual disease in chronic myelogenous leukemia by quantitative polymerase chain reaction

The polymerase chain reaction (PCR) has become a standard method for highly sensitive detection of the bcr/abl rearrangement in patients with chronic myelogenous leukemia (CML) or acute lymphoblastic leukemia (ALL). The exquisite sensitivity of the PCR facilitates the detection of residual leukemic cells after chemotherapy or after bone marrow transplantation. However, the detection of minimal residual disease does not yield any information on the malignant potential of the bcr/abl-rearranged cells. Qualitative PCR is therefore of limited prognostic value in the monitoring of residual leukemia. We have adapted the PCR for quantitative evaluation of cells carrying the bcr/abl rearrangement and by means of two exemplary cases of CML patients after bone marrow transplantation and under treatment with alpha-interferon, respectively, we show that this new technique is suitable for the long term follow-up of the activity of the residual bcr/abl rearranged clone. Longitudinal monitoring of residual disease by the technique presented provides a novel tool for detection of incipient relapse at a very early stage.

Detection of gene expression by PCR amplification of RNA derived from frozen heparinized whole blood

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Pure red cell aplasia in a case of Ph negative BCR/ABL rearranged CML with t(12;14)(q23;p11)

A patient with chronic myelogenous leukemia (CML) associated with pure red cell aplasia (PRCA) is reported. The occurrence of PRCA has been described previously in sporadic cases of Philadelphia chromosome (Ph) positive CML. In this patient, however, the Ph-chromosome was not detected; cytogenetic analysis revealed a t(12;14)(q23;p11) as the sole abnormality. Molecular studies by Southern and PCR analyses showed the rearrangement of the BCR and ABL sequences and expression of the chimeric bcr/abl mRNA, thus confirming the diagnosis of CML. To our knowledge, this is the first report on a case of PRCA associated with Ph negative CML at diagnosis. The possible connection between CML and PRCA is discussed.

Non-radioactive detection of the rearranged BCR/ABL sequences amplified by polymerase chain reaction

The polymerase chain reaction (PCR) is a powerful technique for the detection of the bcr/abl rearrangement in chronic myelogenous leukemia (CML). It allows the exponential amplification of the rearranged region, thus facilitating its detection. The specificity of the bcr/abl cDNA sequence amplified by PCR is most commonly verified by hybridization to a 32P-labeled probe. In this paper, an assay for the colorimetric detection of the amplified bcr/abl fragment is described, which offers several advantages over the use of radioactive probes. We adapted the PCR for synthesis and simultaneous labeling of DNA fragments with a non-radioactive steroid compound called digoxigenin. This labeling procedure was used to generate a digoxigenin-labeled internal probe for the chimeric bcr/abl mRNA. The assay described is based on the hybridization of the amplified bcr/abl sequence to the non-radioactively labeled probe and on the subsequent detection by an enzyme-linked immunoassay and enzyme-catalyzed color reaction. Using this protocol, we investigated 20 patients with CML along with six healthy individuals and two cell lines derived from patients with CML for the presence of the bcr/abl rearrangement. It is shown that the assay is both highly sensitive and specific and that it is readily applicable to the routine diagnosis of CML. In addition, the assay could be adapted to a number of clinical diagnostic uses.

Nonradioactive labeling of probe with digoxigenin by polymerase chain reaction

Probes nonradioactively labeled with the steroid hapten digoxigenin have several intriguing properties, including a high sensitivity equivalent to that of radioactive probes, speed in detection, low hazard potential in handling, and possibility of long-term storage. The use of polymerase chain reaction for labeling probe has been demonstrated to offer various advantages including efficient labeling of fragments as small as 100 bp, direct labeling of genomic DNA, and labeling with subnanogram amounts of input DNA. We therefore investigated whether this technique could be adapted for labeling with a relatively large molecule such as digoxigenin. In this report, we show that the polymerase chain reaction is a very efficient technique for synthesis of digoxigenin-labeled DNA and we present an extremely simple procedure for purification of the non-isotopically labeled fragments.

Beta 2-microglobulin. A reliable parameter for differentiating between graft rejection and severe infection after cardiac transplantation

We investigated the role of beta 2-microglobulin as a noninvasive parameter to monitor acute rejection and severe infection in 45 consecutive heart transplant recipients. Endomyocardial biopsy revealed moderate (41 patients) or severe (three patients) rejection in 44 patients. Severe infections of bacterial septicemia (11 patients), bronchopneumonia (two patients), and viral infection (seven patients) were detected by a meticulous schedule of various clinical and laboratory tests. beta 2-Microglobulin levels in serum, generally corrected for serum creatinine, were significantly elevated in patients with infections (median, 6.3 mg/l; range Q10-Q90, 3.47-10.27 mg/l) compared with levels in patients with rejection (p less than 0.0001) or in patients in obviously good condition (p less than 0.0001). At the onset of acute rejection, the median corrected beta 2-microglobulin serum level was 1.56 mg/l (range Q10-Q90, -0.05-3.46 mg/l) and was significantly different from the control group (p less than 0.01). In addition, density function and empirical quantile analyses allowed us to define ranges of beta 2-microglobulin levels that would differentiate between rejection (2.05-3.46 mg/l) and infection (greater than 3.46 mg/l). With these values, sensitivity and specificity were 0.9 and 0.938 for detection of infection and 0.23 and 0.925 for detection of rejection, respectively. By means of beta 2-microglobulin, two cases of infection were misinterpreted as rejection (10%), and four of 44 rejections were mistaken for infections (9%). We conclude that measurements of beta 2-microglobulin may improve the management of heart transplant patients.

Rapid dot blot quantitation of viral DNA and amplified genes in less than 1,000 human cells

The copy number of intracellular DNA sequences can be quantitated rapidly with great sensitivity in 100 to 1,000 cells as starting material. The method applies DNA from lysed cells to a charged nylon membrane that permits successive hybridizations with probes for different genes or DNA sequences. This method was tested with eight types of human cells, including leukemic cells, and has detected Epstein-Barr virus (DNA virus) in immortalized cells, integrated HTLV-I (RNA retrovirus) in infected cells, and determined copy numbers of the amplified multiple drug-resistant gene in human cells resistant to various cytotoxic agents. It could also be used for estimating copy number of transfected DNA in human or other mammalian cells. The described method is not as sensitive as polymerase chain reaction may potentially prove, but is easily quantitated for accurate clinical diagnosis where sensitive and quantitative assays must be carried out on a limited number of cells. Examples of the method's clinical application are the staging of human neuroblastomas and the evaluation of oncogene amplification, which has prognostic value for both overall survival and relapse time in breast cancer patients.

Duration of first remission as an indicator of long-term survival in chronic myelogenous leukaemia

Approximately 31 patients with chronic myelogenous leukaemia (CML) are documented in the literature who survived more than 10 years after diagnosis. We present a CML-patient whose survival of 27 years is probably the longest reported so far. The analysis of the course of disease in these patients revealed that the duration of unmaintained first remission after chemotherapy is of high prognostic significance. In 17 of 24 evaluable patients the remission lasted more than 1 year and in another five at least 6 months (mean 73.8 months, range 0-240 months). In most patients busulfan was used as initial therapy. There was no correlation between the amount of drug given and the duration of remission or survival. Other parameters such as sex, age, initial leucocyte counts, differential count, haemoglobin, platelet count or spleen size seemed to have no prognostic relevance. While approximately 25% of CML patients with typical duration of survival exhibit a Ph1 chromosome mosaicism only, this finding was present in nearly half of the long-term survivers.

B-lymphocytic hairy cells contain no HTLV-II DNA sequences

HTLV-II has been found in some cases of the rare T-cell form of hairy-cell leukemia (HCL) and in a leukopenic chronic T-cell leukemia mimicking HCL. We asked whether the virus is implicated in the more frequent B-cell form of HCL. DNA extracted from the mononuclear cells derived from spleen (eight cases) or peripheral blood (eight cases) of 16 patients with the B-cell form of HCL was probed. No viral sequences were detected at levels of sensitivity as low as one viral genome in five cells. Therefore HTLV-II may not be involved in the B-cell form of HCL.

Interferon alpha-2 for hairy cell leukemia: evidence for induction of RNA synthesis in hairy cells and failure to correlate enhancement of natural killer cells with elimination of hairy cells

The effect of human recombinant interferon alpha 2 (IFN alpha 2) on hairy cells obtained from 16 patients was evaluated. All patients promptly responded to induction of remission with 2 X 10(6) U/m2 interferon alpha 2 b, three times a week, sc. In order to achieve a more detailed insight into the mode of action of interferon in this disease, we determined the influence of IFN alpha 2 on the incorporation of radiolabeled thymidine and uridine into hairy cells. While both 3H-thymidine and 3H-uridine incorporation were unaffected by IFN alpha 2 in a 3-hour incubation period, a significant increase in uridine incorporation into hairy cells, but not CLL cells, was observed after 24 h. Cell surface marker analysis performed with monoclonal antibodies did not reveal a quantitative alteration of the immunophenotype of hairy cells in vitro. In addition, natural killer cells, assessed by monoclonal antibodies and a cytotoxicity assay against K 562 cells, were found to be decreased in 9 out of 10 patients prior to therapy. Although IFN alpha 2 could stimulate natural killer cells in vivo, we did not find a consistent correlation between the activation of these cells and the response to therapy. We conclude, therefore, that NK cells play no major role in the regression of hairy cells. Furthermore, IFN alpha 2 does not alter antigenic determinants in vitro, but leads to an enhanced incorporation of 3H-uridine into hairy cells in vitro, thus indicating a possible role for the induction of RNA synthesis in vivo.