Comparison between the monoclonal antibodies Ki-67 and PC 10 in 125 malignant lymphomas

The monoclonal antibody (MAb) Ki-67 detects a nuclear proliferation-associated antigen which corresponds to a non-histone protein with a molecular weight of 395 and 345 kD. Its prognostic relevance has been assessed in both lymphoid and non-lymphoid tumours. The MAb PC10 picks up the proliferating cell nuclear antigen (PCNA), which is a 36 kD nuclear protein associated with the cell cycle Whereas Ki-67 works only in fresh material. PC10 detects a fixation-resistant epitope of PCNA. Preliminary data have revealed a linear relationship between Ki-67 and PC 10 reactivity in normal lymphoid tissue and in non-Hodgkin's lymphomas (NHLs). We applied Ki-67 and PC 10 to frozen and routine sections, respectively, from 25 examples of Hodgkin's disease (HD) (14 nodular sclerosis, 6 lymphocyte predominance, 5 mixed cellularity) and 100 NHLs (corresponding to the main varieties of the updated Kiel classification). The results obtained can be summarized as follows: (1) both MAbs gave rise to extremely variable results within the same category of NHLs; (2) most Hodgkin and Reed-Stern berg cells (50-98 per cent) were labelled by the reagents; (3) Ki-67 and PC10 stained a similar ratio of neoplastic cells in 65 and 76 per cent of NHL and HD cases, respectively; in the remaining instances, no correspondence was observed, the PC10-positive elements usually outnumbering the Ki-67-positive ones significantly. These discrepancies, which might be due to low PCNA catabolism and/or PCNA expression by quiescent cells, underline the need for further kinetic and clinico-pathologic studies in order to define the specific relevance of PC 10.     

Frequent expression of Epstein-Barr virus latent membrane protein-1 in tumour cells of Hodgkin's disease in HIV-positive patients.

Epstein-Barr virus (EBV) is believed to be implicated in the aetiology of non-Hodgkin's lymphomas developing in immunodeficient individuals including AIDS patients. EBV has also been associated with Hodgkin's disease (HD), where the genomes have been demonstrated in the Hodgkin and Reed-Sternberg cells in some of the cases. Recent evidence has shown that EBV genomes are transcribed in these cells, because the EBV-encoded latent membrane protein-1 (LMP-1) can be demonstrated in the tumour cells in about half of the HD cases in HIV-negative patients using immunohistochemistry. LMP-1 is of special interest as a possible oncogenic agent because of its strong transforming capacity in vitro. In this study we have examined the expression of LMP-1 in HD of HIV-positive patients compared with HD in HIV-negative patients. We investigated 18 lymph nodes from 16 HIV-positive patients with HD (eight mixed cellularity, nine nodular sclerosis, one unclassified) using the CS.1-4 anti-LMP-1 monoclonal antibodies, which can usually be applied successfully to archival biopsy material. In each case, 50-90 per cent of the tumour cells were labelled. Staining was excellent for both fixatives used (4 per cent buffered formalin, Bouin's fluid). It is concluded that EBV-encoded LMP-1 is firmly associated with HD of HIV-positive patients. This is most conspicuous in the nodular sclerosing subtype HD in HIV-positive patients, in which 100 per cent were LMP-1 positive as compared with 32 per cent of nodular sclerosis HD in HIV-negative cases in a previously published series. This difference is statistically significant (P < 0.001). The possible biological and clinical significance of this difference should therefore be studied in larger series.     

Proliferating cell nuclear antigen (PCNA) expression in Hodgkin's disease.

Previous studies of the proliferating cell fraction in Hodgkin's disease (HD) have been directed towards the classical Hodgkin and Reed-Sternberg cells (HRS) to the exclusion of the background population and have not included cases of nodular lymphocyte predominant Hodgkin's disease (NLPHD). Using an antibody to proliferating cell nuclear antigen (PCNA), we have determined the growth fraction of HRS cells and L&H cells in paraffin sections of 15 cases of classical HD [12 nodular sclerosis (NS), 3 mixed cellularity (MC)] and eight cases of NLPHD. By double staining with anti-PCNA and antibodies to B cells (CD20) and T cells (CD45RO), we also determined the growth fraction and immunophenotype of the background population in each case. In classical HD, 50.4 per cent of HRS cells were PCNA-positive and judged to be proliferating, which is comparable to previous studies, while in NLPHD 76.9 per cent of L&H cells were PCNA-positive. In both classical HD and NLPHD, the majority of PCNA-positive cells in the background were T cells, which showed a growth fraction of 57.8 and 68.5 per cent, respectively; in comparison, only 4 per cent of B cells were PCNA-positive in each type of HD. L&H cells are widely accepted to be B cells and there is growing evidence that HRS cells are also B cell-derived. Our results underline a relationship between classical HD and NLPHD and suggest that the characteristic histological features of both diseases may be caused by the production and release of cytokines from altered B cells.     

bcl-1 rearrangement. Frequency and clinical significance among B-cell chronic lymphocytic leukemias and non-Hodgkin''s lymphomas.

The authors investigated the structural organization of the bcl-1 locus, a putative oncogene associated with reciprocal chromosomal translocation t(11;14), by Southern blot hybridization analysis and its frequency, distribution, and prognostic significance in a panel of 156 clinically and pathologically well-defined B-cell chronic lymphocytic leukemias (CLLs) and non-Hodgkin's lymphomas (NHLs). The authors detected bcl-1 rearrangements in only 2 of 42 CLLs and 4 of 114 NHLs, specifically 3 of 29 diffuse small lymphocytic and 1 of 10 diffuse small cleaved cell and none of 5 diffuse intermediate lymphocytic, 13 follicular predominantly small cleaved, 17 follicular mixed small cleaved and large cell, 4 diffuse mixed small and large cell, 26 diffuse large cell, and 10 diffuse small noncleaved cell lymphomas. None of seven cases of Rai stage III or IV CLL or seven diffuse large cell lymphomas occurring as Richter's syndrome exhibited bcl-1 rearrangements. In conclusion, the bcl-1 locus rearranges in only about 4% of B-cell CLLs and NHLs, is predominantly rearranged in low-grade B-cell neoplasms, and does not appear to be preferentially associated with those occasional CLLs and low-grade NHLs displaying clinical aggressiveness, advanced clinical stage, or large cell transformation (Richter's syndrome). Therefore the demonstration of bcl-1 rearrangement does not appear to have clinically useful prognostic significance.     

Alterations on the 5' noncoding region of the BCL-6 gene are not correlated with BCL-6 protein expression in T cell non-Hodgkin lymphomas.

The BCL-6 proto-oncogene is expressed in germinal center B lymphocytes, in their neoplastic counterparts, and in a subpopulation of germinal center and perifollicular T lymphocytes. Rearrangements and/or mutations of the 5' noncoding region of the bcl-6 gene have been demonstrated in a large majority of diffuse large B cell lymphomas. Some, but not all, of these genetic alterations lead to dysregulation of the protein. Recently, anaplastic large cell lymphomas with T and null cell phenotypes, as well as T lymphoblastic lymphomas, have also been reported to exhibit immunoreactivity to the anti-BCL-6 antibody. We collected 33 T cell non-Hodgkin lymphomas (T-NHLs) and analyzed their expression of the BCL-6 protein by immunohistochemistry and investigated the organization of the bcl-6 gene by Southern blot and single strand conformation polymorphism (SSCP). The expression of BCL-6 was demonstrated in 37.5% of lymphoblastic (LBL), 40% of anaplastic large cell (ALCL), and 33% of peripheral T cell lymphomas (PTCL). BCL-6-positive malignant cells exhibited the CD4+ or CD4+/CD8+ phenotype. The bcl-6 gene was in a germline configuration in all T-NHLs examined, and a mutation at the first exon-intron boundary region structure of the wild-type bcl-6 gene was detected in 3 of 12 PTCL. One case of PTCL with mutations of the 5' noncoding region expressed BCL-6. In conclusion, expression of the BCL-6 protein is demonstrable independently of bcl-6 alterations in T-NHLs. This further suggests that molecular mechanisms other than rearrangements and/or mutations of the 5' noncoding region of the bcl-6 gene can result in expression of the protein. Whether these lymphomas arose from T cells expressing BCL-6 or expressed BCL-6 as part of the malignant transformation process needs to be determined. Finally, structural alterations of bcl-6 are rare in T-NHLs, but mutations do occur in the 5' noncoding region. We suggest that expression of BCL-6 in T cells may facilitate lymphomagenesis by repressing critical cytokines and cell cycle regulators.     

A Specific Monoclonal Antibody (PG-B6) Detects Expression of the BCL-6 Protein in Germinal Center B Cells

The BCL-6 gene is frequently involved in translocations occurring at the 3q27 locus and is rear-ranged in approximately 30% of diffuse large cell lymphomas and in a small fraction of follicular lymphomas. The BCL-6 gene encodes for a Kruppel-type zinc-finger protein, the cell/tissue expression and function of which is unknown. In this study, we describe a new monoclonal anti-body (PG-B6) that is specificaly directed against a fixative-sensitive epitope on the amino-terminal region of the BCL-6protein. By immunocytochemical analysis, BCL-6 localizes in the nucleus where PG-B6 staining gives a microgranular/diffuse pattern with exclusion of the nucleoli. The main reactivity of PG-B6in tonsil and spleen is with the nuclei of germinal center B cells, whereas B cells within the mantle and marginal zones do not express BCL-6. No other lymphoid cells in the tonsil express BCL-6 except for a subset of CD3+/CD4+ intrafollicular and interfollicular T cells. A few lymphoid cells of unknown phenotype express BCL-6 in the thymus. Extra-lymphoid BCL-6 expression includes a weak nuclear positivity of epithelia. In non-Hodgkin's lymphomas, BCL-6 expression parallels that observed in normal lymphoid compartments, eg, expression in germinal center-derived tumors (follicular and diffuse large cell lymphomas), but not in mantle cell and marginal zone lymphomas. In most diffuse large cell lymphomas, the BCL-6 protein is expressed at high levels in cases with or without BCL-6 gene rearrangements. These findings indicate that BCL-6 expression is specifically regulated during B lymphocyte development and suggest that BCL-6 may play a role during B cell differentiation in the germinal center.     

Genomic rearrangements of the c-myc proto-oncogene in human malignant lymphomas

Southern blot analysis of EcoRI-digested DNAs was used to study the genomic configuration of the human proto-oncogene c-myc in tissue samples from a series of 28 human malignant T-cell and B-cell lymphomas. Rearrangements of c-myc were found in 12 (43 per cent) of the cases. In all but one of these the intensities of the hybridization signals from the aberrant c-myc-homologous fragments were much less than that from the 13 Kbp germ-line fragment, suggesting that only a subpopulation of the cells in the tumour carried rearranged myc gene sequences. No relationship was found between the rearrangement of c-myc and cell lineage or differentiation stage, though non-germ-line c-myc-homologous DNA fragments were more commonly found in tumours classed as high-grade according to National Cancer Institute criteria.     

CD40 ligand is constitutively expressed in a subset of T cell lymphomas and on the microenvironmental reactive T cells of follicular lymphomas and Hodgkin's disease.

Although CD40 has been extensively studied in B- and T-cell non-Hodgkin's lymphomas (NHLs)/leukemias, and more recently in Hodgkin's disease (HD), little is known about the expression of its ligand (CD40L) in lymphoproliferative disorders other than T-cell NHLs/leukemias. A series of 121 lymphoma/leukemia samples, including 35 cases of HD, 34 T-cell and 39 B-cells NHLs, 2 cases of adult T-cell leukemia/lymphoma, and 11 cases of T-cell acute lymphoblastic leukemia, were evaluated for CD40L expression by immunostaining of frozen tissue sections and flow cytometry with the anti-CD40L monoclonal antibody M90. CD40L was constitutively expressed by neoplastic cells in 15 of 36 (42%) T-cell NHLs/adult T-cell leukemia/lymphomas, almost invariably those displaying the CD4+/CD8- phenotype, whereas no CD40L-expressing tumor cells could be found in B-cell NHL and HD. Among T-cell acute lymphoblastic leukemias, CD40L was detected only on 2 cases displaying a stem-cell-like phenotype. In follicular B-cell lymphomas a large number of CD40L-expressing CD3+/CD4+ T lymphocytes were found admixed with tumor cells within the neoplastic follicles and in their surrounding areas. In the nonfollicular B-cell lymphomas, CD40L-positive CD3+/CD4+ T lymphocytes were few or absent. In all HD subtypes other than the nodular lymphocytic predominance, CD40L-expressing CD3+/CD4+ T lymphocytes were numerous in the HD-involved areas and were mainly located in close proximity to the Reed-Sternberg cells. Our data indicate that in human lymphomas CD40L is preferentially expressed by a restricted subset of T-cell lymphomas, mostly with CD4 immunophenotype. Finally, we have provided morphological evidence that CD40L may play an important role in the cell contact-dependent interaction of tumor B-cells (CD40+) within the neoplastic follicles or Reed-Sternberg cells (CD40+) in HD-involved areas and the microenvironmental CD3+/CD4+/CD40L+ T lymphocytes.     

The interrelationship of Hodgkin's disease and non-Hodgkin's lymphomas--lessons learned from composite and sequential malignancies.

While Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) have long been regarded as distinct disease entities, recent observations suggest a closer association. The analysis of cases in which these diagnoses are made in the same anatomic site (composite lymphomas) or in separate sites (simultaneous or sequential HD and NHL) indicates that this phenomenon occurs more frequently than would be expected by chance alone. The most common form of composite lymphoma is coexistent nodular lymphocyte-predominant Hodgkin's disease (NLPHD) and large cell lymphoma (LCL) of B cell phenotype. This finding is consistent with a B cell origin for the abnormal cells in NLPHD, suggesting that LCL represents a form of histologic progression, with the existence of a clonal relationship between the two components. The association of other forms of HD (nodular sclerosis or mixed-cellularity) and NHL is less common, but still significant. As with NLPHD and LCL, one may observe composite lymphomas, or the diagnosis of HD may precede or follow the diagnosis of NHL. The vast majority of NHLs associated with HD are of B cell origin, most commonly follicular lymphomas. An association between HD and B cell chronic lymphocytic leukemia (CLL) is also observed. In selected cases, Reed-Sternberg (RS) cells are seen in a background of otherwise typical CLL, and some of these patients have progressed to disseminated HD. These findings suggest that, at least in some cases, HD may be clonally related to an underlying B cell malignancy, and that the RS cell may be an altered B lymphocyte.(ABSTRACT TRUNCATED AT 250 WORDS)     

IgH AND TcR-γ GENE REARRANGEMENTS IDENTIFIED IN HODGKIN'S DISEASE BY PCR DEMONSTRATE LACK OF CORRELATION BETWEEN GENOTYPE,PHENOTYPE, AND EPSTEIN–BARR VIRUS STATUS

Analysis of IgH and TcR-γ genes using consensus primers identifying junctional regions of rearranged genes by polymerase chain reaction (PCR) was performed on tissues involved by Hodgkin's disease (HD) in 90 cases and was correlated with the immunophenotype of Hodgkin and Reed–Sternberg (HRS) cells and the presence of Epstein–Barr virus (EBV) within these cells. Clonal IgH gene rearrangements were found in 1/5 cases of lymphocyte predominance (LP) subtype and none was positive for EBV. In 85 cases of classic HD, no IgH or TcR-γ gene rearrangements were found in 51 (60 per cent) cases. A similar percentage, but not the same cases, were of null (non-B, non-T) phenotype. Of 30 cases where a B phenotype was assigned to HRS cells, nine had IgH gene rearrangements, three had TcR-γ gene rearrangements, and two had both genes rearranged. None of the five cases assigned to T phenotype of HRS cells showed rearrangement of TcR-γ genes, but two cases showed rearranged IgH genes. Among 41 cases of null phenotype, ten had IgH gene rearrangements, five had TcR-γ gene rearrangements, and three cases had both genes rearranged. Whereas EBV was detectable in HRS cells in 17/43 classic HD cases of assigned B phenotype, EBV was also detectable in 2/5 cases of assigned T phenotype and in 21 cases with the null phenotype. Furthermore, there was no correlation of EBV with the presence or lack of IgH or TCR-γ gene rearrangements. Of the remainder, half (30 per cent) expressed antigens associated with lymphocytes without an appropriate genotype. The results confirm lymphocyte-lineage committed cells at the origin of HRS cells in 40 per cent of cases. Any hypothesis of a non-lymphocytic origin of HRS cells will require the inducibility of CD30 on candidate precursors and the methodology for probing genetic events in such cells to be addressed. © 1997 by John Wiley & Sons, Ltd.     

Overexpression of p53 in Hodgkin's disease: Lack of correlation with Epstein–Barr virus infection

Recent work has shown that p53 gene mutations are frequently found in Epstein-Barr virus (EBV)-positive and EBV-negative cases of Burkitt's lymphoma but not in EBV-associated undifferentiated nasopharyngeal carcinomas (NPCs). Similar viral gene expression patterns are observed in undifferentiated NPCs and in EBV-positive cases of Hodgkin's disease (HD), suggesting that the contribution of the virus to the pathogenesis of these malignancies may also be similar. We have analysed 116 cases of HD for EBV association and for immunohistologically detectable overexpression of p53. p53 overexpression was detected in the tumour cell population of 37 (32 per cent) of the cases. Fifteen cases showed p53-specific labelling of more than 40 per cent of tumour cells; in six of these, virtually all tumour cells were stained. In eight cases, between 5 and 40 per cent of tumour cells were labelled, and in another 14 cases, less than 5 per cent of tumour cells expressed detectable amounts of p53. EBV-positive HD cases were found in all groups with different levels of p53 overexpression as well as amongst p53-negative cases. While a more detailed analysis of the p53 gene in HD is required, these data show that overexpression of p53 in HD is heterogeneous and that there is no simple correlation between EBV infection and p53 overexpression.     

Non-Hodgkin's lymphomas. analysis of 109 Japanese cases with the use of LSGJ classification.

Recently the Lymphoma Study Group of Japan (LSGJ) proposed a new classification of non-Hodgkin''s lymphomas (NHLs), diving NHLs into the follicular group consisting of three subsets and the diffuse group, 7. Each subset of the diffuse group is further divided into B or T cell types according to immunologic markers and/or morphologic prediction. In the review of 118 malignant lymphomas, the authors studied the 109 cases of NHLs, attempting to assess the clinicopathologic utility of this classification. Morphologic criteria, enzyme histochemistry, and immunoperoxidase technique were used to ensure the accuracy of the immunologic phenotyping. The results suggest that the LSGJ classification is easily reproducible and yields a more precise clinicopathologic correlation than traditional, morphologic classifications. Consistent with similar studies in Japan, this study demonstrated a low incidence of Hodgkin''s disease (7.6% of all lymphomas) and follicular lymphomas (8.3% of all NHLs) and a high incidence of T cell lymphomas (34.9% of all NHLs). The incidence (45.9%) of extranodal presentation was high. These four features seem characteristic of lymphomas in Japan.     

In vivo expression of the CTLA4 inhibitory receptor in malignant and reactive cells from Human lymphomas

The CTLA4 receptor is a CD28 homologue which induces inhibitory effect on activated T-cells. Peripheral T-cells proliferate spontaneously in CTLA4-deficient mice. These results led to an analysis of CTLA4 expression in human lymphomas (n=82) including Hodgkin's disease (HD) and non-Hodgkin's lymphomas (NHLs), using immunohistochemistry. CTLA4 was present in neoplastic cells from most (10/11) T-cell malignancies, except for anaplastic and lymphoblastic subtypes (0/4). Malignant B-cells from rare (3/55) B-NHLs (all of follicular subtype) were also CTLA4-positive. Other B-NHLs (52/55) were negative in malignant B-cells and occasionally positive in T-cells. Reactive small lymphocytes, but not Reed–Sternberg cells, from all (12/12) HD cases were strongly CTLA4-positive. The CTLA4 ligands CD80 and CD86 were simultaneously expressed in most CTLA4-negative lymphoma cases. CTLA4 is thus expressed either in the reactive or in the malignant cell populations, depending on the lymphoma subtype. These results provide new insights leading towards therapeutic strategies based either on enhancement of anti-tumour immunity by CTLA4 blockade in reactive lymphocytes or on triggering of a CTLA4-mediated inhibitory pathway in lymphoma cells. © 1997 John Wiley & Sons, Ltd.     

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

The results of genotypic analysis of 29 cases of malignant lymphoma are reported and the application of this technique for differentiating between Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) is evaluated. Five cases with a differential diagnosis which included HD and NHL were analysed. These results are compared with those obtained for six B-cell NHLs, nine T-cell NHLs, and nine cases of HD. This report suggests that gene rearrangement analysis is useful in some cases in which the differential diagnoses includes HD and NHL as the absence of gene rearrangements is more consistent with a diagnosis of HD than of NHL. Two monoclonal antibodies reactive with the variable region of T-cell receptor beta-chain and molecular probes to the relevant variable region genes were used to assist in the diagnosis of T-cell lymphoma. This report confirms that genotypic analysis is useful diagnostically when the results are assessed in the context of the histopathological findings.     

BCL-2 in primary central nervous system lymphomas. Immunohistochemistry and molecular biology

BCL-2 is a membrane protein known to be an apoptosis inhibitor. It is the product of the bcl-2 gene located on chromosome 18. Several different tumors show BCL-2 over-expression as result of a translocation or independently from it. More than 85% of follicular lymphomas and a smaller number of diffuse large cell B lymphomas contain t(14;18) (q32;q21). The aim of this study was to investigate the immunohistochemical expression of the BCL-2 protein and to ascertain, by means of traditional PCR (Polimerase Chain Reaction), its possible dependence from t(14;18) (q32;q21) in 9 primary central nervous system lymphomas. Six cases (67%) shoved immunohistochemical BCL-2 over-expression and 3 cases (33%) had t(14;18). Precisely: 2 cases (22%) had immunohistochemical BCL-2 over-expression and t(14;18) (q32;q21); 4 cases (44%) had BCL-2 over-expression without translocation; 1 case (11%) did not show diffuse BCL-2 over-expression in presence of the traslocation; the remaining 2 cases (22%) did not demonstrate BCL-2 over-expression or t(14;18) (q32;q21). In conclusion, our results indicate primary central nervous system lymphomas frequently show BCL-2 over-expression that in some case may be related to t(14;18) (q32;q21). Nevertheless, t(14;18) (q32;q21), as evaluated by traditional PCR, may not correspond to diffuse immunohistochemical BCL-2 positivity.     

Composite lymphoma. A clinicopathologic analysis of nine patients with Hodgkin's disease and B-cell non-Hodgkin's lymphoma

Nine patients had composite lymphoma in which Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL) involved the same anatomic site. Two of these patients had relapses of their tumors. In one, the initial biopsy specimen contained follicular and diffuse large cell NHL with unclassifiable HD, but the relapse showed diffuse large cell NHL with nodular sclerosis HD. In the other patient, both biopsy specimens showed follicular mixed NHL; the HD component in the initial biopsy specimen was nodular sclerosis, whereas, at relapse, it had the appearance of interfollicular HD. In the remaining seven patients, the HD component was subclassified as nodular sclerosis (three specimens) or mixed cellularity (three specimens), or it was unclassifiable (one specimen). The NHL component was categorized as diffuse large cell (two specimens), diffuse large cell immunoblastic (two specimens), follicular and diffuse large cell (one specimen), diffuse mixed small and large cell (one specimen), and lymphocytic lymphoma of intermediate differentiation (modified Rappaport classification) (one specimen). Paraffin section immunoperoxidase studies were done on the NHL component in eight patients (nine specimens) and on the HD component in six patients (seven specimens). In each of these, the NHL component was leukocyte common antigen (LCA) positive and Leu-M1 negative. In addition, the neoplastic cells were L26 positive and UCHL-1 negative, indicating a B-cell phenotype. In five of seven immunophenotyped cases, Reed-Sternberg (RS) and Hodgkin's (H) cells from the HD areas were Leu-M1 positive and LCA negative, reflecting an immunophenotype that is typical of non-lymphocyte-predominant HD. In two specimens, the malignant cells were negative for Leu-M1 and LCA (with positive internal controls). Composite lymphomas composed of HD and NHL are unusual, and cases of coexistent HD of the non-lymphocyte-predominant subtype and NHL are even less common. The results of the current study and a review of the literature indicate that this phenomenon usually involves a B-cell NHL that coexists with HD, perhaps further suggesting a close relationship between the malignant cells of HD (RS and H cells) and B lymphocytes.