Analysis of phenotype and genotype of individual cells in neoplasms

A method to codetect introduced genes and their products in gene therapy protocols

To monitor the presence of introduced genes and the distribution of the encoded proteins in host tissues after gene transfer, we combined fluorescence in situ hybridization (FISH) and immunohistochemistry in two separate gene therapy paradigms. In brain tissue sections from animals injected with pHSVlac vector, we localized nuclei containing vector DNA both in cells expressing and not expressing beta-galactosidase (beta-gal). This suggests that the efficiency of gene transfer is affected not only by gene delivery, but also by cellular controls on gene expression. In a second paradigm, following myoblast transplantation, we detected donor nuclei in the muscle of a patient with Duchenne's muscular dystrophy. The donor nuclei were either surrounded by host nuclei or apparently fused in the patient's muscle fiber producing dystrophin. The combined FISH and immunohistochemistry assay offers greater sensitivity and more information than currently used polymerase chain reaction and protein detection methods.

Megakaryocytes carry the fused bcr-abl gene in chronic myeloid leukaemia: a fluorescence in situ hybridization analysis from bone marrow biopsies

Histological examination of bone marrow biopsies shows that about one-third of chronic myeloid leukaemia (CML) patients exhibit an increase of megakaryocytes. The megakaryocytic predominance may be so striking that differentiation from other chronic myeloproliferative disorders (CMPD) may be difficult in some CML patients. Megakaryocytes in CML are clonal as demonstrated by loss of glucose-6-phosphate dehydrogenase isoenzymes. The Ph translocation, fusing the abl and bcr genes on chromosomes 9 and 22, however, obviously occurs as a second step in tumour development. So far, the Ph translocation has not been assigned explicitly to megakaryocytes. The question is whether the megakaryocytic cell lineage could harbour the bcr/abl fusion in those CML cases with striking proliferation of megakaryocytes but lack this genetic defect in cases with normal or decreased megakaryocyte counts. We therefore performed triple-colour fluorescence in situ hybridization (FISH) for portions of the bcr and abl genes flanking the breakpoint in CML in paraffin sections of CML cases with normal and with increased numbers of megakaryocytes. This method allows identification of the bcr/abl fusion in single, morphologically intact cells, whereas conventional cytogenetics requires lysis and thus destruction of the cell. Among the 21 CML patients examined by FISH, 10 were informative for bcr and abl genes and displayed distinct hybridization signals within nuclei of bone marrow cells. Besides the granulopoietic cells, megakaryocytes of all those patients (4 without and 6 with varying grades of megakaryocytic increase) displayed bcr/abl fusion signals indicative of a Ph translocation. The lack of hybridization signals in the remaining 11 cases indicates that this technique is not of value diagnostically and should be reserved for scientific questions. Positive controls consisted of conventional chromosome preparations from bone marrow aspirates demonstrating the Ph chromosome in all patients examined, and negative controls of paraffin sections of bone marrow biopsies from non-CML patients. These showed no fusion signals in bone marrow cells, including megakaryocytes, using FISH. Our results demonstrate clearly that not only the transforming event but also the Ph translocation leading to the bcr/abl fusion happens prior to the differentiation of the pluripotent stem cell into different myeloid lineages. The megakaryocytic proliferation evident in some CML cases is probably a consequence of the disease progress.

Involvement of natural killer cells in chronic myeloid leukemia

We assessed the involvement of natural killer (NK) cells in chronic myeloid leukemia (CML). We adopted the MAC (morphology antibody chromosomes) method, which allows simultaneous assessment of cell morphology, immunophenotype, and chromosome aberrations in the same mitotic or interphase cells. We examined three patients with CML in chronic phase and two patients with the disease in blast crisis. Patients in the chronic phase of the disease showed no involvement of NK cells, but involvement was detected in one of the patients in blast crisis. In this patient, a proportion of the B cells and lymphoid stem cells was also neoplastic, whereas mature postthymic T cells were normal.

Lineage involvement and karyotype in a patient with myelodysplasia and blood basophilia

We report a 63-year-old woman with myelodysplastic syndrome (MDS), refractory anaemia with ring sideroblasts (RARS), and blood basophilia with pathological forms. Karyotype analysis revealed a complex rearrangement: 46,XX,del(3)(p13p25),del(5)(q13q33),der(16)t(1;16) (p13;q12)/47,idem,add(20)(?p11)/49,idem, + add(1)(q32),add(20)(?p11), + mar/46,XX. Karyotype, immunophenotype and in situ hybridization studies by the MAC (morphology antibody chromosomes) combination technique revealed the chromosomal abnormality in granulocytic/monocytic and erythrocytic metaphase cells. Also mature basophils and other granulocytes were involved with the abnormality. We suggest that our patient with the MDS has a stem cell disorder affecting all myeloid cell lineages and that basophilia constitutes a part of the malignant process.

Prenatal sex determination by in situ hybridization on fetal nucleated cells in maternal whole venous blood

Our aim was to evaluate whether the sex of a fetus could be determined in maternal whole venous blood by in situ hybridization without enrichment of fetal cells. This procedure is virtually without risks to the fetus or the mother. Blood samples were obtained from 59 women at different stages of pregnancy. Twenty preparations were discarded because they were technically unfit for in situ hybridization. Of the remaining 39 pregnant women, 18 had a male fetus, one had male twins, and 20 had a female fetus. Y-positive cells were detected in 12 of the 19 pregnancies with male fetuses and in two of the 20 pregnancies with a female fetus. The frequencies of cells with Y-signals ranged from 1 in 100,000 to 1 in 639. Our results show that fetal cells in maternal blood cannot be reliably used for prenatal diagnosis without prior enrichment of fetal cells.

ISH and PCR study with Y-specific probe/primers

Our main aim was to evaluate whether maternal whole venous blood could be used for determination of fetal sex, when no enrichment of fetal cells was attempted and when "standard" interphase cytogenetics and PCR analysis were adopted. Altogether 39 pregnant women were studied by using ISH and 59 by using PCR. Out of the 59 pregnant women, 26 carried a male fetus and 33 a female fetus. By ISH, Y-positive cells were detected in 12 of 19 pregnancies with a male fetus and in two of the 20 pregnancies with a female fetus. The frequency of the fetal cells ranged from 1 in 639 to 1 in 100,000. By nested PCR with primers flanking a Y-specific repeat sequence, the positive band indicating a male fetus was found in one of the 26 pregnancies with a male fetus and in one of the 33 pregnancies with a female fetus. According to our results, fetal cells in maternal blood cannot be reliably used for prenatal diagnosis without enrichment of fetal cells.

Cell lineage involvement of recurrent chromosomal abnormalities in hematologic neoplasms

Analysis of most hematologic neoplasms indicates the involvement of one or more cell lineages in the bone marrow and/or the blood but rules out the involvement of all lineages in any one neoplasm. It is important to detect lineage involvement in order to clarify which stem cells are involved in leukemia, to predict prognosis, and to select appropriate treatment. Our aim was to study the cell lineage involvement of some of the recurrent chromosomal abnormalities seen in hematological neoplasms. The direct morphology-antibody-chromosomes (MAC) method was used. The deletion 20q in myeloproliferative diseases (MPD), the deletion of 5q and t(1;7) in myelodysplastic syndromes (MDS), and t(3;3) in acute myeloid leukemia subtype M7 (AML-M7) were seen in all or at least in two myeloid lineages. These were interpreted as stem cell abnormalities. Deletion 13q in MPD, t(8;21) in AML-M2 and t(15;17) in AML-M3 were seen in granulocytic lineages only; t(14;18) in non-Hodgkin's lymphoma and trisomy 12 as the sole abnormality in chronic lymphocytic leukemia (B-CLL) were seen only in immunoglobulin light chain clonal B cells; inversion 14 in T-CLL was seen only in T cells, whereas t(15;14) in acute lymphocytic leukemia with eosinophilia (ALL-EO) was seen in lymphoid stem cells but not in mature granulocytes or lymphocytes. Additional abnormalities (in addition to the Philadelphia chromosome) in chronic myeloid leukemia (CML) were seen in all myeloid cell lineages and also in mature granulocytes, B cells, and large granular lymphocytes. Abnormalities in Hodgkin's disease were restricted to CD30-positive Reed-Sternberg cells. Trisomy 8 and monosomy 7 are abnormalities that may be present in either stem cells or any of the single cell lineages.

Ploidy in bone marrow cells from healthy donors: a MAC (morphology antibody chromosomes) study

The ploidy of human bone marrow cells belonging to the megakaryocytic, granulocytic-monocytic and erythrocytic lineages was studied by in situ hybridization using the biotin-labelled Y chromosome-specific DNA probe pY431 and the chromosome 1-specific probe pUC1.77 on cells identified morphologically and immunologically by the MAC procedure. Cells of the granulocytic-monocytic and erythrocytic lineages were seen to be 2N in ploidy, whereas the ploidy of the megakaryocytic lineage ranged from 2N to 32N, with the ploidy classes 4N and 8N being predominant. The frequency of megakaryocytes with 2N chromosomes was also high.

Analysis of genotype and phenotype on the same interphase or mitotic cell. A manual of MAC (morphology antibody chromosomes) methodology

The purpose of this paper is to serve as a MAC (Morphology Antibody Chromosome) manual describing combined methodologies that allow simultaneous and/or sequential analysis of cell morphology, immunophenotype, and banded chromosomes and/or in situ hybridization signals. The MAC techniques used at the Department of Medical Genetics of the University of Helsinki, Finland, are described and modifications or related techniques reported by other authors are discussed. A list of references concerning applications is also given.