Analysis of T-cell receptor and immunoglobulin gene rearrangements in the diagnosis of Hodgkin's and non-Hodgkin's lymphoma

Rare expression of T-cell markers in classical Hodgkin's lymphoma

Hodgkin's and Reed-Sternberg cells of classical Hodgkin's lymphoma are primarily of B-cell origin, although there are instances of T-cell antigen expression suggesting T-cell origin. We comprehensively analyzed expression of various T-cell antigens in 259 classical Hodgkin's lymphoma cases using the tissue microarray technique. Expression of the T-cell antigens CD2, CD3, CD4, CD5, CD7 and CD8 was assessed by immunohistochemistry. Hodgkin's and Reed-Sternberg cells of T-cell marker-positive cases were microdissected and analyzed by a multiplex polymerase chain reaction for clonal immunoglobulin heavy chain- and T-cell receptor gamma gene rearrangements. In all, 12 cases (5%) expressed at least one T-cell marker in the following order: CD2 in 11 cases, CD4 in five, CD3 in two, and CD5 and CD8 in one case each; there were no CD7-positive cases, and five cases (2%) expressed more than one T-cell antigen. In positive cases, a mean fraction of 40% of the Hodgkin's and Reed-Sternberg cells (range 20-100%) expressed the analyzed T-cell markers. Two cases (<1%) evidenced clonal T-cell receptor gamma gene rearrangement. Phenotypic expression of T-cell antigens in Hodgkin's and Reed-Sternberg cells of classical Hodgkin's lymphoma is rare (5%), while genotypically, less than 1% of classical Hodgkin's lymphomas are of possible T-cell origin. Therefore, T-cell antigen expression on Hodgkin's and Reed-Sternberg cells is aberrant in the majority of cases and only infrequently classical Hodgkin's lymphomas are of T-cell origin.

A novel four-color PCR assay to assess T-cell receptor gamma gene rearrangements in lymphoproliferative lesions

We describe a novel 4-color polymerase chain reaction (PCR) assay combined with GeneScan analysis to assess for T-cell receptor gamma chain gene (TCRgamma) rearrangements and evaluate its usefulness in 86 lymphoproliferative lesions. In this assay, each variable region (Vgamma) family primer is 5' end-labeled with a different fluorescent dye, allowing determination of the Vgamma family involved in each TCRgamma rearrangement. PCR products were analyzed by capillary electrophoresis. We detected clonal TCRgamma rearrangements in 60 (98%) of 61 T-cell lymphomas, 2 (15%) of 13 B-cell lymphomas, and 3 (25%) of 12 reactive lesions. These results compared favorably with conventional PCR methods using denaturing gradient gel electrophoresis, which revealed clonal TCRgamma rearrangements in 37 (90%) of 41 T-cell lymphomas, 1 (25%) of 4 B-cell lymphomas, and 2 (25%) of 8 reactive lesions. This 4-color PCR assay is at least equivalent to conventional PCR methods and is convenient, allows accurate size determination of TCRgamma rearrangements, and identifies the specific Vgamma family involved, providing more specific information about TCRgamma rearrangement.

T-cell clonality determination using polymerase chain reaction (PCR) amplification of the T-cell receptor gamma-chain gene and capillary electrophoresis of fluorescently labeled PCR products

We compared the effectiveness of polymerase chain reaction (PCR) and DNA blot analysis (DBA) for detecting clonal T-cell populations and investigated whether a nonradioactive PCR method could be used in routine clinical diagnosis. We analyzed DNA from 117 cases for T-cell clonality by PCR amplification. DBA was performed on 77 of these cases. Denaturing polyacrylamide gel electrophoresis (PCR-PAGE) of radiolabeled PCR products and capillary electrophoresis (PCR-CE) of fluorescently labeled PCR products were used for PCR product separation and quantitation. Complete agreement was obtained between PCR-PAGE and DBA in 67 of 77 cases. One case was positive by DBA and negative by PCR-PAGE, and 3 cases were positive by PAGE and negative by DBA. Five cases indeterminate by DBA were positive by PCR-PAGE, and 1 indeterminate case was negative by PCR-PAGE. In the comparison of PCR-PAGE and PCR-CE, of 63 cases with height ratios less than 2.0, all were negative by PCR-PAGE. Of 52 cases with height ratios of 2.0 or more, 50 were positive by PCR-PAGE. We conclude that PCR-CE is analytically equivalent to DBA and PCR-PAGE for detecting clonal T-cell populations. The PCR-CE method is semiquantitative and, therefore, may be more objective than gel-based methods.

Lack of involvement of known oncogenic DNA viruses in Epstein-Barr virus-negative Hodgkin's disease

Epstein-Barr virus (EBV) is associated with around one-third of cases, but young adult cases are rarely EBV associated. In this study, known oncogenic DNA viruses, including human adenoviruses, papovaviruses and the human herpesviruses-6 (HHV-6) and -8 (HHV-8) were not detected in Hodgkin's disease lesions. These results suggest that an as yet unidentified infectious agent is involved in the pathogenesis of non-EBV-associated Hodgkin's disease.

Mistaken diagnoses of Hodgkin's disease

This article reviews the frequency of and general types of diagnostic errors in Hodgkin's disease (HD) over the past several decades, discusses the most common diagnostic errors in the four histologic subtypes of HD today, and describes some of the clinical and pathologic features that may aid in avoiding a mistaken diagnosis of HD.

Genotypic heterogeneity of node based peripheral T-cell lymphoma

PTCL represents a diverse group of histological entities that defy classification schemes based on normal T cell differentiation, differ in their clinical presentation and behave unpredictably. Genetic analyses of this phenotypically heterogeneous group have clearly shown that histologically defined PTCL may be subdivided on the basis of clonal gene rearrangements. The absence of clonal gene rearrangements in a significant proportion of PTCL cases has increased the complexity of classification. The data presented in this review suggest that a molecular classification would allow true reflection of PTCL aetiology, but carefully coordinated studies are required to evaluate the clinical usefulness of such a classification scheme.

Analysis of antigen receptor genes in Hodgkin's disease

AIM

To analyse the configuration of the antigen receptor genes in Hodgkin's disease.

METHODS

DNA extracted from 45 samples of Hodgkin's disease was analysed using Southern blotting and DNA hybridisation, using probes to the joining region of the immunoglobulin heavy chain gene, the constant region of kappa immunoglobulin light chain gene, and the constant region of the beta chain of the T cell receptor gene.

RESULTS

A single case of nodular sclerosing disease showed clonal rearrangement of the immunoglobulin heavy and light chain genes, all other samples having germline immunoglobulin genes. The nature of the clonal population in the diseased tissue is uncertain, because the intensity of the rearranged bands did not correlate with the percentage of Reed-Sternberg cells present. The T cell receptor genes were in germline configuration in all the samples.

CONCLUSIONS

Antigen receptor gene rearrangement is a rare finding in unselected cases of Hodgkin's disease.

Recent results on the biology of Hodgkin and Reed-Sternberg cells. I. Biopsy material

The most recent sophisticated investigations have provided new and revealing, but also contradictory and controversial information on the biological nature and the cellular origin of Hodgkin and Reed-Sternberg cells (H-RS). Immunophenotypic analyses have shown variable phenotypic antigen expression; but, on balance the data suggest a lymphoid cell expressing T- and/or B-cell-associated markers and certain activation antigens while lacking immunological features of monocytes-macrophages or other lineages. Molecular genetic studies have demonstrated heterogenous findings with respect to rearrangements of T-cell receptor and immunoglobulin genes. Only a small percentage of the cases has rearrangements; this might be due to the threshold of sensitivity of the method combined with the scarcity of the malignant cells. Epstein-Barr virus (EBV) genomes are clonally integrated in the H-RS cells of about half the cases. The significance of these findings--whether EBV is a causative agent or an epiphenomenon--remains to be elucidated. H-RS cells express mRNA and proteins of various cytokines and cytokine receptors implying a predominant role for cytokines in the pathophysiology of HD. The mononuclear and polynuclear H-RS cells are capable of DNA synthesis and nuclear division; the lack of cellular division leads to multinuclearity through the process of endomitosis. Mutations and expression of only a limited number of oncogenes have been tested thus far. Whether the bcl-2 oncogene is involved in HD remains a matter of debate. Aneuploidy and non-random chromosomal abnormalities are the results of cytogenetic analyses of H-RS cells. However, no chromosomal marker specific for HD has yet been found. Thus, while studies of EBV involvement, growth factor production, oncogene expression and chromosomal abnormalities contributed a fair amount of new data on the nature of H-RS cells, only immunophenotyping and genotyping provided some indication of the cellular derivation: an activated lymphoid cell that possibly expresses oncogenes, that probably is infected with EBV, that most likely produces cytokines, that certainly has multiple karyotypic abnormalities.

Recombinant DNA technology and its diagnostic applications

As yet recombinant DNA technology does not appear to have widespread diagnostic application in pathology. However, it does have a useful role to play in specific circumstances in at least three main areas: a it can provide precise diagnostic information about genetic diseases, allowing appropriate counselling, and indicating future directions for research on therapeutic intervention, e.g. gene therapy; b micro-organisms can be identified more sensitively and specifically, in fresh or fixed tissue samples, and their genomes can be analysed in fine detail, providing information relevant to the aetiology, epidemiology and pathogenesis of many diseases; c in tumour pathology the main application so far has been to resolve diagnostic problems associated with leukaemias and lymphomas, when other diagnostic procedures have been inconclusive. Specific chromosomal translocations, involving recognized genes, are particularly amenable to diagnosis by these means. Diagnostic applications to solid tumours are yet to be identified, although significant insights into tumorigenesis have been obtained, and these may ultimately lead to the development of useful markers for prognostic and therapeutic purposes.

Phenotypic overlaps between pleomorphic malignant T-cell lymphomas and mixed-cellularity Hodgkin's disease

Histologically diagnosed, or in part questionable, malignant pleomorphic peripheral T-cell lymphomas (pPTCLs, n = 16) and mixed-cellularity Hodgkin's disease (MCHD, n = 12) were objectively compared by the use of combined immunohistochemistry on paraffin sections, test-point analysis of tissue components, and semi-automated nuclear morphometry on semi-thin resin sections. Classical, qualitative histomorphological distinction of these sub-types of lymphomas proved to be valid and is probably still the best method. Quantitative discriminant features, in order of decreasing significance, were: (i) expression by large atypical cells (LACs) of CD45R0, CD43 and CD45 in pPTCLs, and of CD30 and CD15 in MCHD; (ii) means and standard deviations (SDs) of LAC nuclear-profile areas (greater in MCHD than in pPTCLs); (iii) expression of CD3 by LACs in pPTCLs; (iv) prominence of small lymphoid cells in MCHD; (v) higher percentage of medium-sized lymphoid cells in pPTCLs; and (vi) higher SDs of nuclear-profile circularity factor of small lymphoid cells in MCHD. The medians of the largest nucleolar profile areas in LACs per field did not differ in pPTCLs and MCHD, but dispersion of individual values towards higher levels was significantly greater in the latter. Stepwise discriminant analysis of test point and nucleometric variables that best distinguished pPTCLs from MCHD revealed considerable overlaps, and questionable cases tended to be intermediate between the two. In conclusion, our results confirm and expand the notion of intra-group heterogeneity, with indistinct borders and the existence of intermediate phenotypes between these two taxonomic categories of malignant lymphomas.

Viral involvement in Hodgkin's disease: detection of clonal type A Epstein-Barr virus genomes in tumour samples

Thirty-five cases of Hodgkin's disease (HD) were analysed for the presence of Epstein-Barr virus (EBV) and human herpesvirus-6 (HHV-6) DNA. EBV genomes were detected in 11/35 cases while none of the cases was positive for HHV-6. Ten of the EBV-positive cases were subsequently analysed using a probe for the terminal region of the virus; the results suggested that the EBV-infected cells were clonally expanded. EBV subtypes specific DNA amplification was used to demonstrate that EBV subtype A, and not subtype B was present in the EBV-positive cases. The age distribution of the EBV-positive cases indicated a statistically significant trend for an increase in positivity with increasing age. This is the first indication that EBV is significantly associated with any subset of HD patients.

Demonstration of clonality in T-cell lymphoma using an anti-T-cell receptor variable region antibody panel

Frozen sections from 35 T-cell lymphomas were stained with the Diversi-T alpha beta T-Cell Receptor panel which includes seven antibodies to T-cell receptor variable region gene products. In five cases a monoclonal population of T-cells could be demonstrated (one case V beta 5+, three cases V beta 8+ and one case V beta 6+) and in a further case a biclonal population (V beta 5+ and V beta 8+). We conclude that this antibody panel is of limited usefulness for the demonstration of clonality in T-cell lymphoma.