Detection of T-cell receptor-gamma gene rearrangement in lymphoproliferative disorders by temperature gradient gel electrophoresis

Identification of IgH gene rearrangement and immunophenotype in an animal model of Epstein-Barr virus-associated lymphomas

Epstein-Barr virus (EBV) is a human oncogenic herpesvirus associated with lymphoma and nasopharyngeal carcinoma. Because the susceptible hosts of EB virus are limited to human and cotton-top tamarins (Saguinus oedipus), there have been no appropriate animal models until the lymphoma model induced by EBV in human peripheral blood lymphocyte (hu-PBL)/SCID chimeric mice was reported. However, it is still controversial whether the EBV-associated lymphoma induced in hu-PBL/SCID mice is a monoclonal tumor. In this study, we transplanted normal human peripheral blood lymphocytes (hu-PBL) from six donors infected with EBV into SCID mice to construct hu-PBL/SCID chimeric mice. The induced tumors were found in the mediastinum or abdominal cavity of SCID mice. Microscopic observation exhibited tumor cells that were large and had a plasmablastic, centroblastic or immunoblastic-like appearance. Immunophenotyping assays showed the induced tumors were LCA-positive, CD20/CD79a-positive (markers of B cells), and CD3/CD45RO-negative (markers of T cells). A human-specific Alu sequence could be amplified by Alu-PCR. This confirmed that induced tumors were B-cell lymphomas originating from the transplanted human lymphocytes rather than mouse cells. EBER in situ hybridization detected positive signals in the nuclei of the tumor cells. Expression of EBV-encoded LMP1, EBNA-1, and EBNA-2 in the tumors was significantly positive. PCR-based capillary electrophoresis analysis of IgH gene rearrangement revealed a monoclonal peak and single amplification product in all six cases of induced tumors. This indicated that EBV can induce monoclonal proliferation of human B lymphocytes and promotes the development of lymphoma. J. Med. Virol. 88:1804-1813, 2016. © 2016 Wiley Periodicals, Inc.

A comparison of multiplex and monoplex T-cell receptor gamma PCR

T-cell receptor gamma (TCRgamma) PCR is often used to detect clonal T-cell populations. Because TCRgamma contains a limited number of variable (Vgamma) and joining (Jgamma) regions, a small number of PCR primers can be used to assess T-cell clonality. The seven primers used in the current study were described previously and were split into 2 or 3 multiplex primer sets. In this study, a single 7-primer multiplex (7-plex) PCR reaction was compared with all 12 possible monoplex primer combinations on 18 samples previously analyzed for T-cell receptor rearrangements by TCRbeta Southern blot and/or TCRgamma PCR followed by temporal temperature gradient gel electrophoresis. Using fluorescent Vgamma-region primers, unlabeled Jgamma-region primers, and capillary electrophoresis, we show all TCRgamma rearrangements seen by 7-plex PCR on known positive samples were seen following monoplex PCR. However, additional TCRgamma gene rearrangements were seen in monoplex PCR reactions that were not seen in the 7-plex PCR reactions. Monoplex but not 7-plex PCR of known negative samples occasionally showed TCRgamma gene rearrangements, often with less frequently used Vgamma and Jgamma-region primers, and may have represented false positive results. In summary, the single 7-plex PCR reaction correctly identified specimens with TCRgamma clonal populations and represents an improvement over existing assays that use these same primers split into several smaller multiplex reactions. Monoplex PCR has no advantage over multiplex PCR and has the potential to lead to false positive results.

The role of molecular studies in lymphoma diagnosis: a review

Lymphoma classification is based on a multiparametric approach to diagnosis, in which clinical features, morphology, immunophenotype, karyotype and molecular characteristics are important to varying degrees. While in most cases, a diagnosis can be confidently established on the basis of morphology and immunophenotype alone, a small proportion of diagnostically difficult cases will rely on molecular studies to enable a definitive diagnosis. This review discusses the various molecular techniques available including Southern blotting (SB), polymerase chain reaction (PCR), fluorescence in situ hybridisation (FISH)--including multicolour-FISH/spectral karyotyping and comparative genomic hybridisation--and also gene expression profiling using cDNA microarray technology. Emphasis is given to the analysis of antigen receptor gene rearrangements and chromosomal translocations as they relate to lymphoma diagnosis and also in the setting of minimal residual disease (MRD) detection and monitoring. Laboratories performing these tests need to have expertise in these areas of testing, and there is a need for greater standardisation of molecular tests. It is important to know the sensitivity and specificity of each test as well as its limitations and the pitfalls in the interpretation of results. Above all, results of molecular testing should never be considered in isolation, and must always be interpreted in the context of clinical and other laboratory data.

Lymphadenopathy in adult-onset Still's disease mimicking peripheral T-cell lymphoma

Lymphadenopathy (LAP) that is seen in adult onset Still's disease (AOSD) may be confused with lymphoma. Here we present a patient with AOSD and with LAP that histopathologically mimicked T-cell lymphoma.

Detection of mature T-cell leukemias by flow cytometry using anti-T-cell receptor V beta antibodies

A broad array of antibodies directed against the variable (V) region of the T-cell receptor (TCR) beta (V beta) chain has become available in a directly conjugated multicolor format that permits assessment of 19 of 25 V beta families, covering 70% of the normal circulating T-cell repertoire. These antibodies were used to detect expanded T-cell populations in 43 peripheral blood samples submitted for suspected T-cell malignancy. Of 43 samples, 27 were diagnosed as follows: T-cell large granular lymphocyte leukemia, 14 samples; Sézary syndrome, 4 samples; T-cell prolymphocytic leukemia, 5 samples; or T-cell non-Hodgkin lymphoma or T-cell lymphoproliferative disorder not otherwise specified, 4 samples. The remaining 16 samples were determined to be nonneoplastic. All samples were diagnosed before assessment with anti-V beta flow cytometry. By using a cutoff of 1.6 times the upper limit of normal range (ULN) to define malignant restriction of V beta use, pathologic restriction of V beta use was found directly or indirectly in all 27 samples carrying a diagnosis of malignancy and directly in 2 of 16 samples without a diagnosis of malignancy. TCR gene rearrangement studies were used to confirm V beta flow cytometry results. By using a cutoff of 1.6 times the ULN for the detection of malignancy, the antibody panel had a diagnostic sensitivity of 89% for direct detection of pathologic V beta restriction and a specificity of 88%, making it useful for rapid diagnosis of T-cell leukemia.

Effectiveness of capillary electrophoresis using fluorescent-labeled primers in detecting T-cell receptor gamma gene rearrangements

We describe the use of fluorescent-labeled primers to analyze T-cell receptor gamma gene rearrangements (TCR gamma GR) using capillary electrophoresis in the ABI Prism 310 Genetic Analyzer. We also compare the performance with denaturing gradient gel electrophoresis (DGGE). In a single multiplex polymerase chain reaction (PCR) we amplified TCR gamma GR with primers for all known groups of variable region genes, and joining region genes described in lymphoid neoplasms. Ten reactive samples, followed by five cell lines and 25 tumor samples with 41 individual TCR gamma GR (due to many biallelic rearrangements) previously identified by DGGE, were analyzed to validate the technique. The capillary electrophoresis protocol has 92% concordance for both TCR clonal status (23 of 25) and 95% concordance in the number of individual TCR gamma GR (38 of 41) identified by DGGE. The reproducible sensitivity for detecting TCR gamma GR diluted in reactive lymphoid DNA is 2% in clinical applications. Discrimination of predominant rearrangements requires a minimum ratio of two times the height of the normal distribution of polyclonal peaks. Capillary electrophoresis can provide results within 60 minutes for each specimen after PCR is complete. Capillary electrophoresis provides a faster result than sequence-based separation methods and gives an archival electronic record. Fluorescent labeling allows the identification of both the variable and joining gene segments used in a TCR gamma GR. The effectiveness of capillary electrophoresis is similar to DGGE.

Semireannealing, single-stranded conformational polymorphism: a novel and effective tool for the diagnosis of T-cell clonality

Single-stranded conformational polymorphism (SSCP) is often used for the diagnosis of T-cell clonality in lymphoproliferative disorders. We introduce a semireannealing SSCP (SR-SSCP) protocol that is rapid, reproducible, and effective. By denaturing and reannealing the polymerase chain reaction (PCR) product before high-resolution polyacrylamide gel electrophoresis, it is possible to generate a diagnostic fingerprint for each case with clonal T-cell receptor-gamma (TCR-gamma) gene rearrangement detected after PCR with TCR-gamma specific consensus primers. Discrete and distinct denatured single-stranded DNA band profiles characterize the rearranged TCR-gamma clones. In the same gel, the clone size may be estimated in the reannealed double-stranded PCR DNA and can be assessed down to the 2% clonal T-cell population level. Eighty-four cases, including 37 T-cell neoplasms, 29 B-cell neoplasms, and 18 reactive lymph node samples were analyzed by SR-SSCP. Clonal TCR-gamma rearrangement was diagnosed in 32 out of 37 T-cell neoplasms but in none of the B-cell tumors or reactive lymph node samples corresponding to sensitivity and specificity of 86.5% and 100%, respectively. We compare the results of SR-SSCP to those obtained by capillary electrophoresis and direct sequence analysis with 100% correlation. This novel method is applicable to any system for identification and quantitation of microheterogeneity in PCR products.

Detection of clonal T-cell receptor-gamma gene rearrangement by PCR/temporal temperature gradient gel electrophoresis

Limited combinatorial and junctional diversity in TCR-gamma gene rearrangement can result in amplification products that are difficult to interpret when analyzed by conventional gel electrophoresis methods that separate DNA based on size (polymerase chain reaction [PCR]/polyacrylamide gel electrophoresis [PAGE]). We describe a simple approach to the detection of clonal TCR-gamma gene rearrangement using temporal temperature gradient gel electrophoresis (TTGE) that uses a gradual and uniform increase in the temperature of a constant denaturing gel to resolve different DNA molecules based on base pair composition. We tested 42 clinical specimens (30 blood specimens and 12 formalin-fixed paraffin-embedded tissues) for T-cell clonality by PCR/PAGE and PCR/TTGE. Concordant results were obtained in only 22 specimens (52%). Of the 20 discordant cases, 18 samples were positive by TTGE and negative by PAGE. For all of the discordant cases, the TTGE yielded results that correlated better with the clinical data than did the PAGE method. We conclude that PCR/TTGE is more accurate and easier to perform than current methods for detecting clonal populations of T cells.

Evaluation of a new paraffin-reactive CD7 T-cell deletion marker and a polymerase chain reaction-based T-cell receptor gene rearrangement assay: implications for diagnosis of mycosis fungoides in community clinical practice

BACKGROUND

T-cell deletion and T-cell receptor (TCR) gene rearrangement studies are helpful in the early diagnosis and subsequent management of mycosis fungoides (MF). However, this often requires fresh-frozen tissue that can be difficult to obtain and evaluate in community clinical practice. A new CD7 antibody, the most sensitive and specific T-cell deletion marker, and a new TCR-gamma gene rearrangement polymerase chain reaction (PCR) assay (TCR-gamma PCR) are now available on routine paraffin-embedded biopsy specimens.

OBJECTIVE

Our purpose was to assess the utility of CD7 deletion and TCR-gamma PCR in the diagnosis of MF using routine paraffin-embedded biopsy material.

METHODS

Cases of MF (n = 17) with matching frozen tissue immunohistochemistry and benign reactive dermatoses (lichen planus; n = 27) were assessed for CD7 (Clone: CD7-272) deletion and TCR-gamma PCR using paraffin-embedded biopsy specimens.

RESULTS

Excellent concordance comparing frozen and paraffin embedded CD7 immunostaining (88%) was observed. CD7 deletion and TCR-gamma PCR was sensitive (94%) and specific (96%) for a diagnosis of MF using paraffin-embedded biopsy specimens.

CONCLUSION

In the diagnosis of MF, detection of CD7 deletion and monoclonal TCR rearrangements can be successfully performed in a cost-effective, timely fashion using routine formalin-fixed paraffin-embedded biopsy specimens.