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Results for “clonality”

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PubMed1999

Detection of immunoglobulin kappa light chain rearrangements by polymerase chain reaction. An improved method for detecting clonal B-cell lymphoproliferative disorders.

The clonal determination of B-cell lymphoproliferative disorders by immunoglobulin heavy chain (IgH) rearrangement by polymerase chain reaction (PCR) is widely used. However, few attempts have been made to detect immunoglobulin kappa light chain (Igkappa) gene rearrangement using PCR. We studied 145 cases of B-cell neoplasms, along with 58 atypical and 18 reactive lymphoproliferative disorders, using newly designed degenerate oligoprimers recognizing the framework 3 (FR3kappa) and the joint (Jkappa) regions of the Igkappa gene. PCR products were analyzed on nondenaturing polyacrylamide gel (ndPAGE). Clonal B-cell determination was further investigated using IgH rearrangement and t(11:14) or t(14:18). By combining these methods, we detected either clonality or translocation in 117 of 137 cases (85%) in mature B-cell neoplasms. The additional analysis of Igkappa rearrangement improved sensitivity from 66% to 85%. To investigate whether the Ig gene configuration could be characterized using Igkappa PCR in B-cell neoplasms showing severe breakdown of genomic DNA, 18 selected cases were analyzed. Successful amplification was detected in 72% of the cases using either FR3/2-JH and/or FR3Jkappa oligoprimers. Finally, clonality was detected in 21 of 58 atypical B-cell proliferations, and among them, the atypical marginal cell (54%) and atypical large cell (50%) proliferations showed the highest frequency of clonal immunoglobulin gene products. We concluded that PCR/ndPAGE analysis of Igkappa is a sensitive, rapid, and efficient method for assessing clonality in conjunction with IgH and specific translocation analysis. This approach is particularly useful in the characterization of B-cell lymphoproliferative disorders in archival material with poor preservation of the genomic DNA.

Clone Cells↗

PubMed2002

Assessment of clonal relationships in malignant lymphomas.

DNA sequencing of the antigen receptor genes remains the gold standard for the establishment of clonal relationships between samples. However, a variety of strategies may be employed as surrogates for the determination of the actual sequence of the clonally rearranged antigen receptor genes. The methods described in this chapter provide a framework for the rapid determination of clonal relationships between (microdissected) lymphoid populations. All of the methods described are PCR-based because of its versatility and ability to utilize very small amounts of DNA. For illustration purposes, the descriptions have been confined to B-cell populations. Although not described here, Ig kappa or Ig lambda PCR may also be utilized for determination of B-cell clonality and clonal relationships in the same manner. Similarly, the principles utilized may be extended to T-cell populations and T-cell receptor chain genes. Regardless of the methodology or targets involved, it is strongly recommended that all assays on microdissected material be run on parallel replicates of each sample to ensure reproducibility of results. The information about clonal relationships obtained by LCM has more than an academic significance and has utility in routine diagnostics for the establishment of minimal residual disease and the determination of microscopic disease recurrence vs the development of a secondary malignancy.

Cloning, Molecular↗

PubMed2003

Determination of cutoff values to detect small aneuploid clones by interphase fluorescence in situ hybridization: the Poisson model is a more appropriate approach. Should single-cell trisomy 8 be considered a clonal defect?

We applied a dual-color interphase in situ fluorescence hybridization (I-FISH) technique using centromeric probes specific to chromosomes 7 and 8 on 20 control samples in order to define the statistical model best suited to determine cutoff values for detection of small abnormal clones. We found that the Poisson model is a more appropriate approach than a Gaussian model. Then, based on the analysis of 91 samples from 80 patients with myelocytic malignant hemopathies and either clonal or nonclonal -7 or +8 as determined with conventional cytogenetics (CC), we compared the respective power of I-FISH and CC for detection of aneuploidy, with special emphasis on the potential contribution of I-FISH as a complement to CC in the case of small abnormal clones. The I-FISH results were positive in samples with clonal -7 or +8 according to CC analysis. Whereas I-FISH was negative in samples with nonclonal -7 according to CC, thus confirming the reliability of the criteria used to define the clonality of -7; the situation was different with nonclonal +8. I-FISH revealed the clonality of +8 in most samples with single-cell +8. In several cases, however, the unquestionable clonal nature of +8, as evidenced during follow-up, could not be established with either CC or I-FISH according to accepted criteria. Our data suggest that, in case of a single metaphase with +8, the general rule should be amended and the single-cell +8 should be considered and reported as potentially clonal.

Aneuploidy↗

PubMed1997

Cytogenetic and interphase cytogenetic analyses reveal chromosome instability but no clonal trisomy 8 in Dupuytren contracture.

The results of cytogenetic and FISH analysis performed in 26 cases of Dupuytren contracture are reported. Clonal or sporadic chromosome changes were found in 18 cases (69%). Clonal changes consisted of: +2, +16, -10, -Y, add(1)(p23), del(2)(q21), t(3;16)(p21;q24), add (3)(p24), del(18)(q21), t(Y;14)(p12;q24), +mar. The results differ from those obtained in normal palmar fascia used as control, in which -Y and +Y were the only clonal changes found in 2 of 11 analyzed cases (18%). No clonal trisomy 8 was found. FISH analysis performed in 11 cases (centromeric probe specific for chromosome 8) failed to show the presence of a cell population with +8. Clonal and sporadic structural changes were different from case to case and no clustering breakpoint was observed. The significance of the chromosome instability leading to clonal and sporadic chromosome changes not specific to Dupuytren contracture are discussed.

Aged↗

PubMed1998

Clonality markers in polycythaemia and primary thrombocythaemia.

Our current understanding of the pathogenesis of the myeloproliferative disorders is based on the assumption that they represent a clonal disorder resulting from transformation of a haematopoietic stem cell. Clonality assays exploit the fact that female cells have only one active X-chromosome. Methods for determining X chromosome inactivation have been devised at the protein (G6PD isoenzymes); DNA (HUMARA; phosphoglycerate kinase (PGK); hypoxanthine-phosphoribosyl transferase (HPRT) and RNA (G6PD; P55; IDS) levels. In this type of RNA assay the product of the active X chromosome is quantified by studying polymorphisms present in mRNA. The presence of skewed lyonization in normal females is a potential limitation to the method, although the use of T cells as a control makes it possible to distinguish clonal haematopoiesis from skewed lyonization. However, the phenomenon of acquired skewing in normal elderly women means that X-inactivation patterns in elderly patients must be interpreted with caution. Clonality studies have been conducted in polycythaemia vera (PV) and essential thrombocythaemia (ET) patients. They usually demonstrate a clonal X-inactivation pattern in granulocytes and/or platelets but a polyclonal pattern in T cells. However, in both ET and PV a significant minority of patients exhibit polyclonal haematopoiesis with polyclonal patterns in granulocytes/platelets. Female patients with polyclonal haematopoiesis differ from those with clonal haematopoiesis in terms of age and platelet count and possibly in their requirements for treatment. This new technology for the investigation of the MPD seems promising for understanding certain clinical aspects of these diseases and may be introduced for evaluation of new modalities of treatment.

Adolescent↗

PubMed2005

Rapid detection of clonal T-cell receptor-beta gene rearrangements in T-Cell lymphomas using the LightCycler-polymerase chain reaction with DNA melting curve analysis.

Various molecular methods have been developed to diagnose clonal T-cell receptor (TCR) gene rearrangements in clinical samples. Most polymerase chain reaction strategies for detecting clonal TCR gene rearrangements rely on either gel or capillary electrophoresis. However, a cumbersome manual transfer step separates amplification from analysis. Recently, we developed a novel polymerase chain reaction assay using the LightCycler system to detect clonal immunoglobulin heavy chain gene rearrangement. In the current study, we extend this work to include the TCR. We report that clonal TCR-beta (TCR-beta) gene rearrangements can be detected in less than 1 hour after preparing the DNA by measuring DNA melting immediately after amplification in a single closed capillary tube. We retrospectively studied 52 fresh-frozen tissue samples from patients clinically suspected of T-cell malignancy. A clonal TCR-beta gene rearrangement was detected in 14 samples by DNA melting curve analysis. When DNA melting was compared to the gold standard methods of Southern blot or denaturing gradient gel electrophoresis, it achieved a sensitivity equal to 71% and a specificity equal to 94%. We also compared melting curve analysis and polyacrylamide gel electrophoresis: melting curve analysis reached a sensitivity equal to 100% and a specificity equal to 97%. We conclude that DNA melting curve analysis in the LightCycler system has potential for clinical use as a new, ultra-fast method for the initial diagnosis of clonal TCR-beta gene rearrangements.

Adult↗

PubMed2000

Azo dye-mediated regulation of total phenolics and peroxidase activity in thyme (Thymus vulgaris L.) and rosemary (Rosmarinus officinalis L.) clonal lines.

Thyme (Thymus vulgaris L.) and rosemary (Rosmarinus officinalis L.) clonal lines, which were previously isolated from a heterogeneous seed population by plant tissue culture techniques, have been targeted as potential plants for phytoremediation of organic pollutants such as azo dyes and related aromatic compounds. Three thyme clonal lines and three rosemary clonal lines were tested for the ability to grow on hormone-free medium containing 0.01% of azo dye Poly S-119. The results showed that dye tolerance was associated with reduced phenolics and enhanced peroxidase activity in these clonal lines. There was a clear inverse correlation between total phenolics and peroxidase activity in these plants in response to Poly S-119. The tolerance of these clonal lines showed variations at different growing stages. These observations suggested that the peroxidase activity was inducible. Because peroxidases are involved in lignification, wound healing, aromatic compound degradation, pathogen defense, and stiffening, the results suggest that azo dye stimulated the defense response of thyme and rosemary clonal plants by increasing the peroxidase activity. Stereomicroscopic observations revealed that the azo dye was sequestered within the growing axis of the plant roots, which may also enhance the polymerization of azo dye onto the cell wall with the help of enhanced peroxidase activity.

Azo Compounds↗

PubMed2000

Dermatofibroma is a clonal proliferative disease.

Benign fibrous histiocytoma of the skin or dermatofibroma (DF) has been regarded as a fibrohistiocytic tumor. Whether DF is a neoplastic growth or a reactive process has not been settled. Since a neoplastic process is clonal in nature, clonal analysis of DF was conducted to see if DF is a clonal disease. Fresh specimens of 13 DFs and 2 hypertrophic scars obtained from female patients were studied. The adjacent nonlesional skin tissues served as controls. The clonal analysis was based on the methylation pattern of the polymorphic X-chromosome linked androgen-receptor gene (HUMARA). Eight DFs and 1 hypertrophic scar were heterozygous at the androgen receptor gene and could be analyzed. All 8 informative DFs showed a significant reduction in one of the allelic bands compared with the corresponding bands of the nonlesional tissue after Hha I digestion. Therefore, DF is a clonal proliferative disease. In contrast, 1 hypertrophic scar showed a polyclonal pattern of X-chromosome inactivation. We conclude that DF is a clonal disease favoring a neoplastic process.

Alleles↗

PubMed2002

Favourable response to antithymocyte or antilymphocyte globulin in low-risk myelodysplastic syndrome patients with a 'non-clonal' pattern of X-chromosome inactivation in bone marrow cells.

OBJECTIVE: Antithymocyte and antilymphocyte globulin (ATG/ALG) have a therapeutic effect in about 30% of patients with myelodysplastic syndromes (MDS). We were interested to know whether responding patients achieve clonal or polyclonal remissions. PATIENTS: Ten women with low-risk MDS received either ALG or ATG. Before treatment and 3, 6, and 12 months later, X-chromosome inactivation patterns of peripheral blood T lymphocytes were compared with those of peripheral blood granulocytes or bone marrow cells, using the human androgen receptor gene assay and the phosphoglycerate kinase-1 assay. RESULTS: Six women did not respond to therapy. Prior to treatment, four of them had a monoclonal, one had an oligoclonal, and one had a skewed X-chromosome inactivation pattern (XCIP). Four patients responded to ATG/ALG. Three of them were informative in our X-inactivation assays, and showed a non-clonal XCIP which did not change significantly after treatment with ATG/ALG. CONCLUSION: A non-clonal XCIP in the bone marrow was associated with a response to ATG/ALG. Non-clonal XCIPs do not necessarily imply that there is no pathological clone. By definition, they just indicate that there is no evidence of a clone contributing more than 50% of cells in a sample. Non-clonal XCIPs may therefore be attributable to incomplete clonal expansion. This, in turn, might be explained by a vigorous immune attack against the MDS clone, which simultaneously causes collateral damage in the remaining normal haemopoiesis. In such patients, ATG/ALG may improve normal haemopoiesis by relieving the immunological pressure on the innocent bystanders.

Aged↗

PubMed1990

A role for clonal inactivation in T cell tolerance to Mls-1a.

Clonal deletion plays a major part in the maintenance of natural self-tolerance in both normal and transgenic mice. Self antigens that are expressed in the thymus result in the physical elimination of autoreactive thymocytes at a particular stage in their development. For example, the majority V beta 6- and V beta 8.1-bearing T cells that recognize the minor lymphocyte-stimulating antigen, Mls-1a (ref. 10) , are clonally deleted in the thymuses of normal mice and transgenic mice expressing Mls-1a (refs 2, 3, 9). In contrast, a very different mechanism of tolerance involving the functional inactivation, but not elimination, of autoreactive cells, termed clonal inactivation or clonal anergy, has been implicated in some experimentally manipulated systems of tolerance. To test further the mechanisms involved in self-tolerance, we have generated transgenic mice expressing a V beta 8.1 beta chain on greater than 95% of peripheral T cells and have tested tolerance to Mls-1a in these mice. Surprisingly, a significant fraction of the CD4+ peripheral cells that survived deletion were non-responsive in vitro to any stimulus tested. Naturally occurring tolerance to a self antigen expressed in the thymus can thus be mediated by clonal anergy, as well as by clonal deletion.

Animals↗

PubMed2000

Clonal analysis of micronodules in virus C-induced liver cirrhosis using laser capture microdissection (LCM) and HUMARA assay.

Most hepatocellular carcinomas (HCC) arise from malignant transformation of regenerative cirrhotic nodules. Because HCC has a very poor prognosis, detection of these premalignant lesions may improve the management of patients with cirrhosis. In this regard, clonal analysis of liver micronodules should be of particular interest in order to differentiate polyclonal regenerative micronodules from monoclonal neoplastic potentially malignant micronodules. To address this issue, 112 micronodules from 15 cases of explanted liver cirrhosis were carefully microdissected from paraffin-embedded tissue using a laser capture microscopy system. Clonal analysis was performed by analyzing X-chromosome inactivation, as indicated by the methylation status of the human androgen receptor gene (HUMARA). For each microdissected micronodule, a large set of pathological features was evaluated and correlated with their clonal status. Clonal analysis showed that 57 micronodules (51%) were monoclonal and 55 (49%) were polyclonal. Prevalence of monoclonal nodules ranged from 25% to 71% according to cases. In all cases, mono- and polyclonal nodules were randomly distributed in the cirrhotic liver. Although the clonal status was not significantly affected by the presence or absence of macronodules in the adjacent liver, size of monoclonal micronodules was significantly larger than size of polyclonal micronodules (mean size of the monoclonal nodules: 3 + 0.1 mm vs mean size of the polyclonal nodules: 2.5 +/- 0.1 mm, p = 0.007). Among the elementary pathological features evaluated, only the presence of iron overload was correlated with a monoclonal status (p = 0.04). In conclusion, clonal analysis of liver cirrhosis shows that 51% of micronodules are monoclonal lesions, supporting the notion that liver cirrhosis is a multineoplastic lesion. Because monoclonality is a marker of neoplasia, cirrhosis with accumulation of monoclonal nodules may be carefully followed, and monoclonal nodules should be screened for additional markers to assess their biological behavior.

Adult↗

PubMed1997

Determination of clonality in patients who present with diagnostic dilemmas: a laboratory experience and review of the literature.

Identification of rearrangements in the immunoglobulin heavy chain (IgH), T cell receptor (TCR) and other genes assists in the classification of hemopoietic disorders. This study reviews a 5 year experience of genotyping as an assessment of clonality in a central referral laboratory. Patients were referred for assessment if abnormal hemopoietic populations were identified and where standard morphology, cytochemistry or immunophenotyping techniques were equivocal and unable to establish the diagnosis. Analysis of the antigen receptor genes (IgH gene and TCR gamma locus) was performed in 230 patients by either Southern blotting or the polymerase chain reaction (PCR). Clonal rearrangements of either loci could be demonstrated in 91/230 patients: 56/161 patients analyzed by Southern blotting and 48/125 analyzed by polymerase chain reaction. A subgroup of patients (n = 88) was analyzed for rearrangement of the immunoglobulin heavy chain gene by both techniques. Discordant results were observed in 18 of these patients (20%). Analysis of the TCR gamma locus in a separate group demonstrated discordant results in eight of 40 patients examined (20%). Clinical outcome could be available in 61 patients (median time: 42 months, range 1-68 months): for those in whom a rearrangement was detected approximately 80% went on to develop a lymphoproliferative disorder although this diagnosis was not able to be made at the time the sample was taken. In a subset of patients (n = 14) who presented with lymphocytosis after bone marrow transplantation (seven) or solid organ transplant (seven), clonal lymphoid populations were demonstrated in approximately 50% of cases. The majority of these cases demonstrated the presence of Epstein-Barr virus (EBV) by PCR. The clonality of EBV infection was assessed by Southern blotting and the significance of these findings are discussed. This study explores the differences between Southern blotting and PCR as applied to the study of antigen receptor rearrangement studies. We conclude that detecting a clonal population is valuable in patients where standard diagnostic techniques are equivocal. However, the inability to detect a clonal population should be treated with caution and interpreted in light of other investigations.

Blotting, Southern↗

PubMed2003

Design and standardization of PCR primers and protocols for detection of clonal immunoglobulin and T-cell receptor gene recombinations in suspect lymphoproliferations: report of the BIOMED-2 Concerted Action BMH4-CT98-3936.

In a European BIOMED-2 collaborative study, multiplex PCR assays have successfully been developed and standardized for the detection of clonally rearranged immunoglobulin (Ig) and T-cell receptor (TCR) genes and the chromosome aberrations t(11;14) and t(14;18). This has resulted in 107 different primers in only 18 multiplex PCR tubes: three VH-JH, two DH-JH, two Ig kappa (IGK), one Ig lambda (IGL), three TCR beta (TCRB), two TCR gamma (TCRG), one TCR delta (TCRD), three BCL1-Ig heavy chain (IGH), and one BCL2-IGH. The PCR products of Ig/TCR genes can be analyzed for clonality assessment by heteroduplex analysis or GeneScanning. The detection rate of clonal rearrangements using the BIOMED-2 primer sets is unprecedentedly high. This is mainly based on the complementarity of the various BIOMED-2 tubes. In particular, combined application of IGH (VH-JH and DH-JH) and IGK tubes can detect virtually all clonal B-cell proliferations, even in B-cell malignancies with high levels of somatic mutations. The contribution of IGL gene rearrangements seems limited. Combined usage of the TCRB and TCRG tubes detects virtually all clonal T-cell populations, whereas the TCRD tube has added value in case of TCRgammadelta(+) T-cell proliferations. The BIOMED-2 multiplex tubes can now be used for diagnostic clonality studies as well as for the identification of PCR targets suitable for the detection of minimal residual disease.

Chromosome Aberrations↗

PubMed2006

Polymerase chain reaction-based clonality testing in tissue samples with reactive lymphoproliferations: usefulness and pitfalls. A report of the BIOMED-2 Concerted Action BMH4-CT98-3936.

Lymphoproliferations are generally diagnosed via histomorphology and immunohistochemistry. Although mostly conclusive, occasionally the differential diagnosis between reactive lesions and malignant lymphomas is difficult. In such cases molecular clonality studies of immunoglobulin (Ig)/T-cell receptor (TCR) rearrangements can be useful. Here we address the issue of clonality assessment in 106 histologically defined reactive lesions, using the standardized BIOMED-2 Ig/TCR multiplex polymerase chain reaction (PCR) heteroduplex and GeneScan assays. Samples were reviewed nationally, except 10% random cases and cases with clonal results selected for additional international panel review. In total 75% (79/106) only showed polyclonal Ig/TCR targets (type I), whereas another 15% (16/106) represent probably polyclonal cases, with weak Ig/TCR (oligo)clonality in an otherwise polyclonal background (type II). Interestingly, in 10% (11/106) clear monoclonal Ig/TCR products were observed (types III/IV), which prompted further pathological review. Clonal cases included two missed lymphomas in national review and nine cases that could be explained as diagnostically difficult cases or probable lymphomas upon additional review. Our data show that the BIOMED-2 Ig/TCR multiplex PCR assays are very helpful in confirming the polyclonal character in the vast majority of reactive lesions. However, clonality detection in a minority should lead to detailed pathological review, including close interaction between pathologist and molecular biologist.

Biopsy↗

PubMed1996

Aplastic anaemia patients with clonal X-chromosome inactivation pattern in haemopoietic cells exhibit polyclonal TCRgamma and IgH gene rearrangements.

Previously, we reported that 13/18 (72%) female patients with aplastic anaemia (AA) exhibited a clonal X-chromosome inactivation (XCI) pattern in all haemopoietic lineages. To study the consequences of a clonal haemopoiesis for the randomness of immunoreceptor rearrangements in lymphocytes we determined clonality of T-cell receptor gamma (TCRgamma) and immunoglobulin heavy chain (IgH) gene rearrangements in purified cell fractions. Peripheral blood granulocytes, monocytes, and B and T lymphocytes from 18 female patients in remission from AA were studied by PCR for randomness of XCI and rearrangement at the IgH and TCRgamma locus. 13 patients were informative at the phosphoglycerate kinase-1 (PGK1) and monoamine oxidase A (MAOA) loci. Five of them displayed an clonal XCI pattern in all lineages studied and one patient had a clonal XCI in all lineages, except the T cells. In three cases skin biopsies were also available, exhibiting a polyclonal pattern in two of them, and a reversed skewed pattern in the third. Analysis of the rearrangement patterns at the immunoreceptor loci revealed a polyclonal ladder of bands, irrespective of XCI status in the lymphocyte populations. These results demonstrated that in AA a clonal XCI pattern of the lymphoid compartment is compatible with a polyclonal immunoreceptor rearrangement pattern.

Adult↗

PubMed1997

Analysis of T-cell clonality in bone marrow of patients with acquired aplastic anaemia.

Acquired aplastic anaemia (AA) represents a state of bone marrow (BM) failure which is characterized by BM hypocellularity and pancytopenia. It has been hypothesized that in some AA patients, bone marrow failure is secondary to the targeted destruction of haemopoietic stem cells by autoreactive T cells. The response of T cells to antigenic stimulation has been shown, in a number of animal models and in autoimmune diseases, to result in the (oligo)clonal expansion of positively reacting T cells. For this reason, we studied the utilization of 24 T-cell receptor-variable gene segments (TCRBV) and the clonality in BM aspirates and peripheral blood (PB) of seven AA patients. BM from transplant donors served as controls. Determination of TCRBV gene segment usage revealed no significant differences between patients and controls. Clonality within each family was analysed by single-strand conformation polymorphism (SSCP) analysis. Clonal and clonally predominant bands were seen in BM of three AA patients in five to eight TCRBV families. Clonal rearrangements were encountered less often in BM of control subjects. In conclusion, our results suggest an antigen-driven T-cell response in the BM of predominantly AA patients resulting in oligoclonal T-cell outgrowth.

Adolescent↗

PubMed2000

Microanatomical compartments of clonal and reactive T cells in mycosis fungoides: molecular demonstration by single cell polymerase chain reaction of T cell receptor gene rearrangements.

Mycosis fungoides (MF) is a cutaneous T cell lymphoma, clinically characterized by patches, plaques and tumors occurring in successive stages of the disease. In early MF, an infiltrate consisting of mainly reactive T cells is seen in the papillary dermis while tumor cells are mostly confined to the epidermis. By contrast, later stages show nodular infiltrates formed mostly of tumor cells in the dermis while the epidermis is relatively devoid of tumor cells; however, knowledge of the localization of clonal T cells has been based on histomorphologic features and immunohistochemical stainings visualizing certain V-beta subfamilies of the T cell receptor (TCR). As these techniques do not allow for an unequivocal identification of clonal tumor cells, we used micromanipulation and single cell PCR amplifying the TCR chain gene rearrangement. A total number of 387 single T cells was isolated from six skin biopsies in five patients in patch, plaque, and tumor stages. Of these, 180 T cells were picked from the epidermis and 207 from the dermal infiltrate. The rearranged TCR-gamma DNA could be sequenced from 181 of 387 T cells. In three of six patients representing all three stages, epidermal T cells with a clonal rearrangement could be amplified. In early plaque stage a higher degree of epidermal T lymphocytes was found than in initial patch, later plaque, and tumor stages with an inverse distribution found for reactive T lymphocytes. In two patients a biallelic rearrangement was demonstrated that had not been detected in prior PCR analysis from blood and skin samples. These data show that clonal (neoplastic) and non-clonal (reactive) T lymphocytes in MF preferentially infiltrate different microanatomical compartments of the skin, depending on the stage of disease. The microanatomically distinct localization of reactive and clonal T cells suggests that the absence of direct contact between tumor and host-defense lymphocytes may contribute to tumor persistence and progression in epidermis, peripheral blood, and deep dermal tumor cell nests, respectively.

Aged↗

PubMed2004

The chronic myeloproliferative disorders: clonality and clinical heterogeneity.

The chronic myeloproliferative disorders (MPD), polycythemia vera (PV), chronic idiopathic myelofibrosis (IMF), essential thrombocytosis (ET), and chronic myelogenous leukemia (CML), are thought to be clonal disorders arising in a multipotent hematopoietic progenitor cell. However, establishing the diagnosis of an MPD other than CML is problematic due to a lack of clinically applicable clonal markers. Furthermore, in some patients, in whom a classical MPD phenotype is present, the hematopoietic stem cells appear to be polyclonal, suggesting that the chronic MPD other than CML may actually be a genetically heterogeneous group of disorders. Furthermore, since the aberrant clone is believed to arise from a multipotent hematopoietic stem cell, the non-CML chronic MPD-ET, PV, and IMF-could be related. Additional unresolved issues regarding the MPD include: identification of the multipotent hematopoietic progenitor cell involved, the molecular basis for the clinical heterogeneity amongst the individual MPD, the clinical significance of clonality in non-CML MPD, and reconciliation of therapy with the clonal and clinical heterogeneity of these disorders. Determination of clonality has largely been carried out using X chromosome-linked polymorphisms, but such studies are limited to women and with increasing patient age are compromised by skewing of allelic expression in both neutrophils and T lymphocytes, making the results difficult to interpret. X chromosome-linked polymorphism studies have indicated that in PV the target stem cell is one that gives rise to both lymphoid and myeloid progenitors. Recently, two epigenetic markers have been identified in the MPD: impaired expression of the thrombopoietin receptor, Mpl, in platelets and megakaryocytes, and overexpression in neutrophils of the mRNA of a gene designated polycythemia rubra vera-1 (PRV-1). The role of these epigenetic abnormalities in the diagnosis of the MPD remains to be established. Currently, given the unresolved issues with respect to the clinical and clonal heterogeneity of the MPD, treatment needs to be tailored individually in patients with an MPD.

Age Factors↗