Powerful strategy for polymerase chain reaction-based clonality assessment in T-cell malignancies Report of the BIOMED-2 Concerted Action BHM4 CT98-3936.

Polymerase chain reaction (PCR) assessment of clonal T-cell receptor (TCR) and immunoglobulin (Ig) gene rearrangements is an important diagnostic tool in mature T-cell neoplasms. However, lack of standardized primers and PCR protocols has hampered comparability of data in previous clonality studies. To obtain reference values for Ig/TCR rearrangement patterns, 19 European laboratories investigated 188 T-cell malignancies belonging to five World Health Organization-defined entities. The TCR/Ig spectrum of each sample was analyzed in duplicate in two different laboratories using the standardized BIOMED-2 PCR multiplex tubes accompanied by international pathology panel review. TCR clonality was detected in 99% (143/145) of all definite cases of T-cell prolymphocytic leukemia, T-cell large granular lymphocytic leukemia, peripheral T-cell lymphoma (unspecified) and angioimmunoblastic T-cell lymphoma (AILT), whereas nine of 43 anaplastic large cell lymphomas did not show clonal TCR rearrangements. Combined use of TCRB and TCRG genes revealed two or more clonal signals in 95% of all TCR clonal cases. Ig clonality was mostly restricted to AILT. Our study indicates that the BIOMED-2 multiplex PCR tubes provide a powerful strategy for clonality assessment in T-cell malignancies assisting the firm diagnosis of T-cell neoplasms. The detected TCR gene rearrangements can also be used as PCR targets for monitoring of minimal residual disease.

Significantly improved PCR-based clonality testing in B-cell malignancies by use of multiple immunoglobulin gene targets. Report of the BIOMED-2 Concerted Action BHM4-CT98-3936.

Polymerase chain reaction (PCR) assessment of clonal immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements is an important diagnostic tool in mature B-cell neoplasms. However, lack of standardized PCR protocols resulting in a high level of false negativity has hampered comparability of data in previous clonality studies. In order to address these problems, 22 European laboratories investigated the Ig/TCR rearrangement patterns as well as t(14;18) and t(11;14) translocations of 369 B-cell malignancies belonging to five WHO-defined entities using the standardized BIOMED-2 multiplex PCR tubes accompanied by international pathology panel review. B-cell clonality was detected by combined use of the IGH and IGK multiplex PCR assays in all 260 definitive cases of B-cell chronic lymphocytic leukemia (n=56), mantle cell lymphoma (n=54), marginal zone lymphoma (n=41) and follicular lymphoma (n=109). Two of 109 cases of diffuse large B-cell lymphoma showed no detectable clonal marker. The use of these techniques to assign cell lineage should be treated with caution as additional clonal TCR gene rearrangements were frequently detected in all disease categories. Our study indicates that the BIOMED-2 multiplex PCR assays provide a powerful strategy for clonality assessment in B-cell malignancies resulting in high Ig clonality detection rates particularly when IGH and IGK strategies are combined.

DNA repair contributes to the drug-resistant phenotype of primary acute myeloid leukaemia cells with FLT3 internal tandem duplications and is reversed by the FLT3 inhibitor PKC412.

The presence of internal tandem duplications (ITD) mutations in the FMS-like tyrosine kinase 3 (FLT3) receptor influences the risk of relapse in acute myeloid leukaemia (AML). We have investigated DNA repair in FLT3-ITD and wild-type (WT) cells. Using the comet assay, we have demonstrated that the FLT3 inhibitor PKC412 significantly inhibits repair of DNA damage in the MV4-11-FLT3-ITD cell line and FLT3-ITD patient samples but not in the HL-60-FLT3-WT cell line or FLT3-WT patient samples. Following the discovery that transcript levels of the DNA repair gene RAD51 are significantly correlated with FLT3 transcript levels in FLT3-ITD patients, we further investigated the role of RAD51 in FLT3-ITD-AML. The reduction in DNA repair in PKC412-treated FLT3-ITD cells was shown to be associated with downregulation of RAD51 mRNA and protein expression and correlates with the maintenance of phosphorylated H2AX levels, implying that PKC412 inhibits the homologous recombination double-strand break repair pathway in FLT3-ITD cells. Using FLT3-short interfering RNA (siRNA), we also demonstrated that genetic silencing of FLT3 results in RAD51 downregulation in FLT3-ITD cells but not in FLT3-WT cells. This work suggests that the use of FLT3 inhibitors such as PKC412 may reverse the drug-resistant phenotype of FLT3-ITD-AML cells by inhibiting repair of chemotherapy-induced genotoxic damage and thereby reduce the risk of disease relapse.

Autologous GVHD following PBSCT, with evidence for a graft-versus-myeloma effect.

The development of GVHD following allogeneic BMT is known to be closely associated with significant antileukaemic activity. Immunological graft-versus-leukaemia (GVL) effects are now well established and are commonly exploited in the treatment of leukaemic relapse following allogeneic transplantation by the use of donor lymphocyte infusions. More recently a graft-versus-myeloma (GVM) effect following allogeneic transplantation has been documented, suggesting that eradication of haematological malignancies following allogeneic transplantation is achieved at least in part by immunological mechanisms. It is now also established that spontaneous GVHD can occur following autologous transplantation and can be induced by cyclosporin A administration. However, there is only limited evidence that the development of autologous GVHD has an antitumour effect. We report for the first time the development of autologous GVHD following PBSC transplantation for myeloma apparently resulting in a GVM effect.

Adjuvant alpha-interferon improves complete remission rates following allogeneic transplantation for multiple myeloma.

Allogeneic transplantation may be curative in a proportion of patients with multiple myeloma (MM), but relapse is a major cause of treatment failure. We sought to improve complete remission (CR) rates by the use of alpha-interferon (alpha-IFN) in patients not in CR when evaluated 4 months post-transplant. We report five of 13 evaluable patients undergoing allogeneic sibling BM or PBSC transplantation for MM between 1990 and 1997 who met the criteria for adjuvant alpha-IFN therapy. A starting dose of 3 MU x 3/week was commenced at median time of day +126 (range day +112-224) post-transplant and was well-tolerated. In contrast to other reports we observed no increased toxicity in terms of GVHD compared to those patients not receiving alpha-IFN therapy and only one patient treated with alpha-IFN has developed chronic GVHD. Durable CRs were achieved in two patients within 8 weeks of starting therapy whilst two other patients required a longer course of alpha-IFN to achieve CR (36 weeks and 30 weeks, respectively). One patient whose paraprotein was rapidly rising at the time of alpha-IFN therapy clinically relapsed despite 6 months of treatment. None of the patients who achieved CR following alpha-IFN therapy have relapsed and we conclude that alpha-IFN is a safe and effective adjuvant treatment for some patients in the achievement of CR following allogeneic transplantation for myeloma.

Low incidence of human herpesvirus 8 in stem cell collections from myeloma patients.

Human herpesvirus 8 is a gammaherpesvirus which may be implicated in the pathogenesis of multiple myeloma. Viral DNA sequences have been found in the bone marrow, peripheral blood and leukapheresis products of myeloma patients. These findings have significant implications for the use of leukapheresed cells in the transplantation and immunotherapy of myeloma. The studies suggest the cell which harbours the virus may be dendritic in origin. We have previously reported that dendritic cells cultured for use in the clinical setting do not harbour HHV-8. In this study, we examined the leukapheresis products of a larger cohort of myeloma patients for the presence of HHV-8 using a highly sensitive PCR technique. A strong association between HHV-8 and myeloma was not confirmed, with only 4% of the patient samples positive for viral sequences. While further study is needed, the current use of apheresis cells and their cultured progeny in the treatment of myeloma should not be compromised.

Cloning of the type VII trimethoprim-resistant dihydrofolate reductase gene and identification of a specific DNA probe.

A 1.3 kb HindIII fragment encoding the type VII trimethoprim-resistant dihydrofolate reductase gene was cloned into pBR322. Unidirectional deletion of this cloned fragment with exonuclease III identified the start of the dihydrofolate reductase gene. An internal 300bp EcoRV fragment was identified which could be used as a specific non-radioactive DNA probe to distinguish bacteria carrying the type VII gene from those carrying genes encoding other known dihydrofolate reductase types.

Use of a non-radioactive hybridisation assay for direct detection of gram-negative bacteria carrying TEM beta-lactamase genes in infected urine.

DNA in infected urines from 81 patients with urinary tract infection was hybridised directly with a non-radioactive DNA probe specific for bacterial genes coding for TEM-type beta-lactamase. The results were assessed by means of a computerised image analysis system and compared with those obtained following isolation of the infecting organism, conventional sensitivity testing and isoelectric focusing (IEF) procedures for the detection of TEM-type beta-lactamase. Of the 27 ampicillin-resistant gram-negative organisms isolated in pure culture from the urines, 14 were shown by both hybridisation and IEF to carry a gene for TEM beta-lactamase production. Only four discordant results were obtained: three "false positive" direct hybridisation results, one due to urine pigmentation, and one, possibly, to a TEM beta-lactamase gene which was not being expressed, and one "false negative" result due to insufficient cell numbers in the urine. The system is capable of screening large numbers of samples and is applicable to any gene for which a suitable DNA probe is available.

Identification of carcinoma cells in peripheral blood samples of patients with advanced breast carcinoma using RT-PCR amplification of CK7 and MUC1.

We have undertaken a pilot study to attempt to identify circulating carcinoma cells in a series of patients with advanced breast carcinoma, using reverse transcription-polymerase chain reaction (RT-PCR) to amplify mRNA of epithelial specific antigens. Using this method to amplify mRNA of MUC1 and cytokeratin 7 (CK7) the sensitivity of the technique was demonstrated by means of diluted concentrations of "spiked MCF7" cells in whole blood, showing a detection limit of 1 in 10(6) (CK7) and 1 in 10(5) (MUC1). Positive results were obtained from the peripheral blood of all nine female patients with advanced breast cancer for CK7 and eight of the nine patients for MUC1. CK7 was however detected in five of 11 healthy controls (eight females, three males) and MUC1 in one of the 11 controls. None of the control group were positive for both CK7 and MUC1, in contrast to eight of the nine patients with advanced breast carcinoma who were positive for both markers. The RT-PCR method thus appears sufficiently sensitive to identify circulating tumour cells in peripheral blood samples from patients with advanced breast carcinoma. However a high proportion of false-positive results was seen in the control population. More extensive investigation is required before the technique is likely to be of benefit clinically.

EuroClonality/BIOMED-2 guidelines for interpretation and reporting of Ig/TCR clonality testing in suspected lymphoproliferations.

PCR-based immunoglobulin (Ig)/T-cell receptor (TCR) clonality testing in suspected lymphoproliferations has largely been standardized and has consequently become technically feasible in a routine diagnostic setting. Standardization of the pre-analytical and post-analytical phases is now essential to prevent misinterpretation and incorrect conclusions derived from clonality data. As clonality testing is not a quantitative assay, but rather concerns recognition of molecular patterns, guidelines for reliable interpretation and reporting are mandatory. Here, the EuroClonality (BIOMED-2) consortium summarizes important pre- and post-analytical aspects of clonality testing, provides guidelines for interpretation of clonality testing results, and presents a uniform way to report the results of the Ig/TCR assays. Starting from an immunobiological concept, two levels to report Ig/TCR profiles are discerned: the technical description of individual (multiplex) PCR reactions and the overall molecular conclusion for B and T cells. Collectively, the EuroClonality (BIOMED-2) guidelines and consensus reporting system should help to improve the general performance level of clonality assessment and interpretation, which will directly impact on routine clinical management (standardized best-practice) in patients with suspected lymphoproliferations.

Rapid detection of a specific trimethoprim resistance gene using a biotinylated DNA probe.

A DNA probe specific for the dihydrofolate reductase (DHFR) type I gene was labelled with biotin by the process of nick-translation and used to screen 83 independently-derived trimethoprim R plasmids from Enterobacteriaceae. Hybridization was detected using streptavidine and a biotin-conjugated alkaline phosphatase to generate an insoluble coloured precipitate following the addition of an appropriate dye. Sixty-eight plasmids (81.9%) hybridized with the probe for DHFR type I. The method could be adapted for use with any antibiotic resistance gene for which a suitable DNA probe is available and has none of the drawbacks associated with the use of radioactively-labelled DNA in hybridization techniques.

Search for viral nucleic acid sequences in the post mortem brains of patients with schizophrenia and individuals who have committed suicide.

Molecular hybridisation has been used to screen several areas of post mortem brain from 20 patients with schizophrenia, 23 individuals who were suspected of having committed suicide and 21 control cases, for viral nucleic acids. Cloned probes were able to detect picogram levels of viral DNA and to quantify herpes simplex type 1 DNA from encephalitic brain, but no sequences hybridising to cytomegalovirus, varicella zoster virus, herpes simplex type I or JC or BK papovaviruses were detected in any of the experimental samples. These findings are discussed with reference to the viral hypothesis of the aetiology of psychiatric disease.

Detection of TEM beta-lactamase genes by non-isotopic spot hybridisation.

A 998 bp fragment of plasmid pBR322, comprising part of the TEM-1 beta-lactamase gene, was labelled with biotin-11-dUTP for use as a DNA probe in a rapid non-isotopic spot hybridisation test. Diluted broth cultures of bacteria producing different beta-lactamases were filtered onto nitrocellulose and lysed in situ. Following pre-hybridisation treatment with proteinase K, hybridisation with the labelled probe was demonstrated using a commercially available streptavidine/polyalkaline phosphatase-based detection system. The probe was highly specific, reacting only with strains producing either the TEM-1 or structurally similar TEM-2 enzyme. An inoculum of 3-4 X 10(6) cells gave optimum positive discrimination. When 90 recent ampicillin-resistant strains of Escherichia coli isolated from patients with urinary tract infections were screened using the system, 72% gave a positive hybridisation signal.

A comparison of the effects of cytotoxic cerebrospinal fluid on cell cultures with other cytopathogenic agents.

Protein synthesis, antigen synthesis, and cell membrane permeability were analyzed after inoculating human diploid fibroblasts with control or cytotoxic CSF, herpes simplex virus type 1 (HSV 1), poliovirus 3, or Clostridium difficile toxin. Whereas protein synthesis and membrane permeability were affected by the viruses, and virus antigens detectable by pooled human serum were synthesized, the bacterial toxin and cytotoxic CSF did not induce any new proteins or antigens, although the cytotoxic CSF reduced cellular protein synthesis levels and caused an increase in the permeability of the cell membranes. The effect of the cytotoxic CSF in cell culture resembles that of a toxin rather than a replicating virus.

Detection of novel trimethoprim resistance determinants in the United Kingdom using biotin-labelled DNA probes.

Two collections of trimethoprim R plasmids, isolated from strains of Escherichia coli during 1978-83 and 1987-8 respectively, were retrospectively screened with specific biotinylated DNA probes for the presence of genes encoding particular DHFR enzymes. The results confirmed that the type I DHFR gene was the predominant plasmid-encoded gene conferring trimethoprim resistance in strains of E. coli from the Nottingham area of the UK, but indicated that genes encoding the more recently recognized types of DHFR enzymes had appeared in the bacterial gene pool and could be recognized with increased frequency in the latter plasmid collection. This was particularly true of the type IIIa and type VII enzymes which together accounted for 27% of the trimethoprim R plasmids examined in 1987-8.

Desmoplasia and its relevance to colorectal tumour invasion.

Some invasive tumours characteristically have an abundant stroma rich in collagen, the production of which is termed the desmoplastic response. It has been suggested that this response may have a protective effect, and act to limit the process of tumour invasion. To investigate this possibility, we have examined various colorectal tumours for inter- and intra-tumoural variations in the desmoplastic response. As markers of this response, the distributions of collagen-I protein and myofibroblasts have been demonstrated by immunocytochemistry, while collagen-I messenger RNA has been demonstrated by in situ hybridization (ISH). Evidence of a desmoplastic response was obvious in carcinomas, but not in non-invasive adenomas. In carcinomas, we found that the response was marked in the tumour centre, where morphological features of active invasion have been reported to be absent. By contrast, we found little evidence of a desmoplastic response at the invasive edge of these carcinomas, where features suggestive of active invasion are prominent: in this location, collagen-I immunostaining was limited and myofibroblasts were sparsely distributed or absent. While our ISH results suggested active collagen-I synthesis in the tumour centre, there was little evidence of collagen-I synthesis in host tissues ahead of the invasion front. On the basis of these and other reported findings, we suggest that, while the desmoplastic response may reduce the invasive activity of neoplastic cells in the tumour centre, it fails to prevent the spread of colorectal cancer because of its deficiency at the invasive edge.

Cytopathogenic cerebrospinal fluid from neurological and psychiatric patients.

Cerebrospinal fluids (CSFs) were examined for the presence of a cytopathogenic component by an in vitro assay. No abnormal proteins were detected in CSF which produced cytopathic effects. The cytopathic effect was associated with high-molecular-weight material which was resistant to enzyme treatment. The effect persisted after extensive ultraviolet irradiation. The presence of the cytopathic effect was associated with increased CSF enolase levels.

Basement membrane collagen-IV synthesis in colorectal tumours.

Many studies suggest that increased proteolysis accounts for the epithelial basement membrane (EBM) breaks commonly seen in carcinomas. As failure to produce or maintain EBM may also be important, we chose to investigate synthesis of basement membrane collagen-IV in human colorectal carcinomas. First, to determine the cellular origin of EBM collagen-IV, species-specific antibodies were used to analyse caecal xenografts of 4 different human colorectal-carcinoma-derived cell lines. The results of this study suggest an exclusively stromal cell origin for EBM collagen-IV. Next, the distribution of periglandular myofibroblasts in carcinomas was examined, since in normal mucosa their location and ultrastructural features suggest that they play a role in EBM maintenance. They were generally abundant in normal mucosa and adenomas, but sparsely distributed in carcinomas, particularly at the invasive periphery where EBM collagen-IV immunostaining is most deficient. Finally, the in situ hybridization technique was used to define cell populations synthesizing collagen-IV. In normal mucosa, no collagen-IV mRNA was detected in any component, while in carcinomas, the mRNA was clearly detectable in vascular endothelial cells but not in any other cell type. Increased vascular collagen-IV production in carcinomas may be at least partly due to tumour-induced angiogenesis, since new blood-vessel formation requires the synthesis of new vascular basement membranes.