Klaus Weber-Matthiesen

Frequent deletions of 6q23–24 in B-cell non-Hodgkin's lymphomas detected by fluorescence in situ hybridization

Deletions of the long arm of chromosome 6 (6q) are among the most frequent chromosome aberrations in malignant lymphomas and often occur as secondary changes in addition to typical translocations, such as t(14; 18). Using fluorescence in situ hybridization (FISH) with two YAC probes hybridizing to 6q23–24 and with the centromeric probe D6Z1 as internal control, we studied 31 cases of low‐grade and eight cases of high‐grade B‐cell lymphoma. Deletions of 6q23–24 were detected in 21 patients (56.8%) by FISH, compared to 13 patients (33.3%) by chromosome analysis. Deletions of 6q23–24 were found by FISH in 5 of 13 cases of small lymphocytic lymphoma, in 2 of 3 cases of mantle cell lymphoma, in 10 of 14 cases of t(14; 18) positive low‐grade follicular lymphoma, and in 4 of 8 cases of high‐grade follicular lymphoma. This study shows that deletions of 6q23–24 are more frequent in B‐cell lymphomas than previously suggested and that they can be detected more sensitively by FISH than by chromosome analysis. Contrary to previous reports indicating that the region 6q23–24 is preferentially deleted in low‐grade lymphomas without t(14; 18), our results indicate that deletions of 6q23–24 appear to be common in other pathological subsets of B‐cell lymphoma as well, especially in follicular lymphomas with t(14; 18). Genes Chromosom. Cancer 18:310–313, 1997.

Which compartments are involved in Philadelphia-chromosome positive chronic myeloid leukaemia? An answer at the single cell level by combining May-Grünwald-Giemsa staining and fluorescence in situ hybridization techniques

Chronic myeloid leukaemia (CML) is believed to represent a stem cell disorder involving all three cell lineages. The typical chromosomal aberration, the Philadelphia chromosome, is the translocation (9;22)(q34;q11). Several studies with cytogenetics, fluorescence in situ hybridization (FISH), or polymerase chain reaction have investigated the presence of the t(9;22) in different cell compartments. However, questions still remain. In six cases of CML we combined the standard May‐Grünwald‐Giemsa staining with FISH at the single‐cell level and were able to demonstrate that not only all maturation stages of granulopoiesis, erythropoiesis, and megakaryocytes, but also plasma cells, eosinophils, basophils and monocytes carried the Philadelphia chromosome in 53–98% of samples. Using immunological identification of single cells we were able to demonstrate that the t(9;22) is detectable in 34% of CD3‐positive T lymphocytes, in 32% of CD19‐positive B lymphocytes, and in 82% of CD34‐positive precursor cells. The results give new insight into the biology of CML and may have implications for future therapeutic strategies.

Secondary acute leukaemias with 11q23 rearrangement : clinical, cytogenetic, FISH and FICTION studies

Three patients with secondary acute leukaemia after treatment with topoisomerase II inhibitor agents are described. Two patients had acute myeloid leukaemia (AML), FAB M5a, one had pro‐B‐acute lymphoblastic leukaemia (ALL). The interval between initiation of chemotherapy and the onset of secondary acute leukaemia was 19–20 months. 11q23 rearrangements were detected in all cases. They were due to translocations t(11;19) (q23;p13.3), t(11;16)(q23;p13) and t(4;11)(q21;q23), respectively. Fluorescence in situ hybridization (FISH) with Yeast Artificial Chromosome (YAC) probe 13HH4 spanning the ALL‐1 gene on 11q23 confirmed that in each case the ALL‐1 gene had been disrupted by the translocations. The study underlined the relationship between the development of secondary acute leukaemias with 11q23 rearrangement and previous chemotherapy with topoisomerase II inhibitor agents. So far, however, only six adult patients with secondary ALL with t(4;11) after treatment with topoisomerase II inhibitor agents have been reported. ALL with t(4;11) mostly occurs in infants or young children. Our patient received epirubicin continuously for >19 months. This indicates that both myeloid and lymphoid leukaemias with involvement of the ALL‐1 gene can be induced by exogenous agents, especially topoisomerase II inhibitors. Thus they may have a common biological background. This hypothesis was substantiated by means of combined immunophenotyping and FISH (FICTION). In the case of AML M5a with t(11;19), the tumour cells with ALL‐1 rearrangement expressed CD34. Moreover, the pro‐B‐ALL with t(4;11) was CD34 positive. These findings suggest that the cell of origin of secondary AML and ALL with 11q23 rearrangement is an immature haemopoietic progenitor cell.

Detection of chromosome 11 alterations in blood and bone marrow by interphase cytogenetics in mantle cell lymphoma

The t(11;14)(q13;q32) translocation is a consistent chromosome change in mantle cell lymphomas. This study investigates the application of fluorescent in situ hybridization (FISH) with chromosome painting probes for interphase cytogenetic analysis in patients with mantle cell lymphomas. Chromosome 11 paints have been able to show splitting of the chromosome signal consistent with the t(11; 14) translocation in interphase cells from bone marrow and blood of patients with mantle cell lymphomas. These include some in clinical remission. The chromosome probes conjugated with fluorescent molecules are hybridized with patients DNA allowing the easy detection of chromosome 11 abnormalities with fluorescent‐light microscopes. Interphase FISH has a higher sensitivity and is quicker than standard metaphase cytogenetics. This may be beneficial in rapid detection of chromosome 11 abnormalities, assisting in the diagnosis of mantle cell lymphomas. In addition, detection of a clonal population of cells is possible.

New insights into the biology of Philadelphia‐chromosome‐positive acute lymphoblastic leukaemia using a combination of May‐Grünwald‐Giemsa staining and fluorescence in situ hybridization techniques at the single cell level

It is sometimes difficult to discriminate chronic myeloid leukaemia (CML) in lymphatic blast crisis from Ph‐chromosome positive acute lymphoblastic leukaemia (ALL). Previous studies have suggested that ALL is restricted to the lymphatic lineage only, whereas CML involves all cell lineages.

Fluorescence in situ hybridization as a diagnostic tool in malignant lymphomas

Abstract Primary and secondary chromosomal abnormalities play an important role in the characterization of biological, pathological, and clinical subgroups of malignant lymphomas. The introduction of fluorescence in situ hybridization (FISH) and the combination of immunophenotyping plus FISH to the diagnosis of lymphatic neoplasms allows the fast and sensitive detection of specific chromosomal changes and provides new insights into the genetic basis of lymphomagenesis. This article reviews the possibilities and limitations of molecular cytogenetic techniques in comparison to cytogenetic and molecular genetic methods and discusses their clinico-pathological impact for non-Hodgkin’s lymphoma and Hodgkin’s disease.

Rationalization of in situ hybridization: testing up to 16 different probes on a single slide.

Although particularly interested in tumor research, investigators in many tumor cytogenetics laboratories cannot afford extensive molecular/interphase cytogenetics studies in addition to routine cytogenetics analyses, primarily because many slides must be stained to examine a few cases using a panel of centromeric probes. Moreover, fluorescence in situ hybridization (FISH) techniques mostly require freshly prepared reagents, such as hybridization mixtures or antibody solutions. These technical requirements are very time-consuming, thus limiting their use in routine screening. We report a significantly economical method for rapid performance of interphase cytogenetics in great numbers of cases. The major advantage if its superior efficiency: up to 16 different probes may be used on one single slide. Moreover, the method is significantly cheaper than other techniques owing to minimal probe consumption. The technique is also best suited if great numbers of new probes, e.g., polymerase chain reaction (PCR)-generated YAC-probes, must be tested for their applicability in FISH.

Clarification of dubious karyotypes in Hodgkin’s disease by simultaneous fluorescence immunophenotyping and interphase cytogenetics (FICTION)

Cytogenetic studies on Hodgkins disease (HD) typically reveal very complex karyotypes with a variety of numerical and structural abnormalities. The confusing thing is that about 10% of cases contain relatively discrete chromosome aberrations, for example a simple trisomy or loss of one single chromosome. Whether these karyotypes really correspond to Hodgkin and Reed-Sternberg (HRS) cells is uncertain. They could, for example, represent early stages in the evolution of the karyotype of the pathognomonic HRS cells. On the other hand, they could be artificial events that occur during the cytogenetic procedure. In our experience, isolated loss of the Y chromosome is the most frequent finding of this type. This aberration is usually considered to be a preparation artifact. However, if one takes into account that in HD up to 50% of male cases with complex karyotypes also lack the Y chromosome, a possible relation to HRS cells must be considered. The technique of simultaneous fluorescence immunophenotyping and interphase cytogenetic analysis (referred to as FICTION) is a powerful tool for studying the nature of cytogenetically abnormal cells. With the FICTION technique we studied four cases of HD in which the chromosome analysis had shown only the loss of the Y chromosome. Our aim was to clarify whether these karyotypes corresponded to the CD30-positive HRS cells. In two cases we found that HRS cells actually lacked the Y chromosome. There was strong evidence, however, that the HRS cells additionally had other chromosome aberrations and thus could not correspond to the cytogenetically determined karyotypes.

Translocation (X;8)(q2?6;q21.3) in a case of systemic mastocytosis.

Mastocytosis is a rare disease which occasionally progresses into mast cell leukemia or other myeloid neoplasms. Here we report on a patient with systemic mastocytosis who was found to have a clone with t(X;8)(q2?6;q21.3) and two copies of der(8)t(X;8). In accordance with these results, interphase cytogenetic analysis revealed that 93% of bone marrow cells contained three centromeric regions of chromosome 8. We suggest that the t(X;8) and the duplication of the translocation chromosome 8 may play a role in the progression of the diseases.

Detection of structural chromosome aberrations in immunophenotyped mitoses

The recently developed MAC (morphology-antibody-chromosome) method allows simultaneous immunophenotype and karyotype analysis in the same cell. To date, application of this new method has been hampered by the poor quality of chromosome banding. In this paper, we describe a modified simultaneous immunofluorescence and Q-banding technique, as well as a new combination of immunohistochemical and fluorescent R-banding methods. By further modifying the MAC method, we were able not only to achieve unequivocal results with weakly expressed antigens but also to improve the quality of the banding techniques, so that even structural chromosome abnormalities were well defined.