Inhibition of tyrosine kinase activity induces caspase-dependent apoptosis in anaplastic large cell lymphoma with NPM-ALK (p80) fusion protein

OBJECTIVE

The t(2;5)(p23;q35) translocation creates a fusion gene NPM-ALK (p80) that encodes a product with tyrosine kinase activity believed to play an important role in development of anaplastic large cell lymphoma (ALCL). Our study was aimed to analyze tyrosine kinase activity and phosphotyrosine in ALCLs. We were also interested in determining the effect of tyrosine kinase inhibitors on survival of ALCL.

METHODS

Eleven cases of ALCL and three ALCL cell lines with t(2;5)(Karpas-299, SUPM2, SU-DHL-1) and 10 Hodgkin's disease (HD) samples were stained with anti-phosphotyrosine antibody. The tyrosine kinase activity, p80 phosphorylation, and the apoptotic effects of two tyrosine kinase inhibitors, herbimycin A and STI-571, were determined on ALCL cell lines.

RESULTS

Herbimycin A had showed both a time- and dose-dependent apoptotic effect on all three cell lines, while STI-571 demonstrated a minimal effect. Following herbimycin A treatment, a decrease in tyrosine kinase activity in the ALCL cell lines and inhibition in NPM-ALK (p80) autophosphorylation was demonstrated by immunoprecipitation and Western blotting. Herbimycin A-induced apoptosis was accompanied by caspase-3 activation. Furthermore, apoptosis induced by herbimycin A was blocked by both z-VAD-FMK and z-DEVD-FMK, suggesting a critical role of caspases.

CONCLUSIONS

These findings indicate that tyrosine kinase activity is a common characteristic of ALCLs and necessary for ALCL cell survival. These findings further suggest that therapies targeting tyrosine kinases, including p80, may have clinical utility.

Quantification of cytomegalovirus (CMV) viral load by the hybrid capture assay allows for early detection of CMV disease in lung transplant recipients

BACKGROUND

We prospectively compared the hybrid capture system (HCS) assay with conventional cell culture and shell vial assay for the detection of cytomegalovirus (CMV) infection and disease in the lung transplant population.

METHODS

Between January 1999 and February 2000, 34 lung transplant patients at Loyola University Medical Center, who were considered to be at risk for CMV disease, underwent surveillance testing for CMV cell culture, shell vial assay and HCS assay according to a pre-determined schedule. In addition, bronchoscopy with bronchoalveolar lavage (BAL) and transbronchial biopsy were performed at regular intervals and for clinical indications. All BAL samples were sent for CMV cultures and biopsy specimens were analyzed for histopathologic evidence of CMV by immunoperoxidase staining using antibody to early immediate nuclear antigen.

RESULTS

Ten patients developed CMV disease/syndrome during the course of the study. The sensitivity, specificity, positive predictive value and negative predictive value were >90% for the HCS assay. The sensitivity of the HCS assay (90%) was statistically significantly higher than the sensitivity of either the SV assay (40%) or the cell culture (50%). In addition, the HCS assay was able to detect CMV 50 +/- 67 days prior to clinical evidence of CMV disease and an average of 36 days prior to the other detection techniques.

CONCLUSION

The HCS assay is a sensitive diagnostic technique able to reliably detect CMV disease earlier than other diagnostic methods in the lung transplant population. Future studies may be able to evaluate whether pre-emptive anti-viral therapy targeted to specific viral loads using the HCS assay will be beneficial in preventing morbidity associated with CMV disease.

Cytologic diagnosis of peripheral T-cell lymphoma manifesting as ascites. A case report

BACKGROUND

Patients with malignant lymphoma seldom present with effusions without a known history of malignancy. Because of this, initial diagnosis of malignant lymphoma by effusion cytology is uncommon, with few reported cases.

CASE

A 75-year-old male presented with fatigue, decreased appetite and progressively increasing abdominal girth over five weeks. Cytologic examination of ascitic fluid obtained by paracentesis revealed non-Hodgkin's lymphoma with a T-cell phenotype, confirmed by immunophenotypic and molecular studies. Approximately one week later, histologic examination of liver and bone marrow revealed involvement by lymphoma, demonstrating immunophenotypic and molecular profiles identical to those obtained from neoplastic lymphocytes recovered from the ascites fluid.

CONCLUSION

This case demonstrates a rare presentation of peripheral T-cell lymphoma, clinically manifesting as ascites. In cases such as ours, where the effusion consists predominantly of small to intermediate-sized lymphocytes, distinguishing lymphoma from reactive lymphocytosis may be difficult. This case not only demonstrates the value of effusion cytology for lymphoma diagnosis but also illustrates how the use of various immunophenotypic and molecular techniques may assist the pathologist in properly diagnosing these difficult cases.

Transfection of caspase-3 in the caspase-3–deficient Hodgkin's disease cell line, KMH2, results in enhanced sensitivity to CD95-, TRAIL-, and ARA-C–induced apoptosis

BACKGROUND

CD95(Fas/apo-1) is a cell surface protein member of the tumor necrosis factor receptor family that serves an important role in the induction of apoptosis in several cell types. Although expression of CD95 has been detected on Hodgkin/Reed Sternberg (HRS) cells in situ, our understanding of the biological significance of this molecule in Hodgkin's disease (HD) is limited.

DESIGN

We analyzed both CD95-related apoptotic signaling and its effects on the expression of several factors involved in the regulation of apoptotic mechanisms including: caspase-3, caspase-8, bcl-2, bcl-x, and Bax in HD cell lines (L-428, L-540, HDLM-2, HS-445, and KM-H2).

RESULTS

HD cell lines showed similar expression levels of CD95 and all but KM-H2 demonstrated variable increases in apoptosis after CD95 stimulation by the agonistic monoclonal antibody, CH11. There was no significant correlation between CD95 sensitivity and constitutive expression levels of caspase-8, bcl-2, bcl-x, and Bax. Caspase-3 transcript was demonstrated by reverse transcriptase polymerase chain reaction (RT-PCR) in all cell lines but protein was at low to nearly undetectable levels in KM-H2 cells. Transfection of KM-H2 cells with pro-caspase-3 resulted in a markedly enhanced apoptotic response to CD95 stimulation that was blocked by pretreatment with the caspase-3 inhibitor, DEVD-FMK. In addition, pro-caspase-3-transfected KM-H2 cells showed significantly increased sensitivity to other caspase-3-dependent apoptotic stimuli, including the death-inducing ligand, TRAIL, and the chemotherapeutic agent, Ara-C.

CONCLUSION

These data demonstrate that caspase-3 expression plays an important role in CD95-mediated apoptosis in HD cell lines. Furthermore, lack of or decreased expression of caspase-3 in HD cells impairs their apoptotic response not only to CD95 but also to other caspase-3-dependent apoptotic stimuli.

Characterization of NF-kappaB expression in Hodgkin's disease: inhibition of constitutively expressed NF-kappaB results in spontaneous caspase-independent apoptosis in Hodgkin and Reed-Sternberg cells

Although the neoplastic cells of classical Hodgkin's disease (CHD) demonstrate high levels of constitutively active nuclear NF-kappaB, the precise physiologic and clinical significance of NF-kappaB expression is currently undefined. Expression of active NF-kappaB p65(Rel A) was evaluated in patient samples of CHD and nodular lymphocyte predominance Hodgkin's disease. The action of the chemical NF-kappaB inhibitors gliotoxin and MG132 and the effect of NF-kappaB inhibition utilizing an adenovirus vector carrying a dominant-negative IkappaBalpha mutant (Ad5IkappaB) were then demonstrated in CHD cell lines (L428, KMH2, and HS445). Hodgkin and Reed-Sternberg (HRS) cells from all patient and cell line specimens showed strong immunopositivity for active p65(Rel A). Expression was also seen in lymphocytic/histiocytic cells from all cases of nodular lymphocyte predominance Hodgkin's disease. After chemical NF-kappaB inhibition, p65(Rel A) was significantly reduced in nuclear extracts from cultured HRS cells as revealed by electrophoretic mobility shift assays. Furthermore, chemical NF-kappaB inhibition resulted in time- and concentration-dependent apoptosis in HRS cells. With the exception of MG132-induced apoptosis in HS445, apoptosis by chemical NF-kappaB inhibition was not significantly altered by preincubation with various caspase inhibitors (z-DQMD-FMK, z-DEVD-FMK, z-VAD-FMK, z-VEID-FMK, and z-IETD-FMK). Regardless of the chemical inhibitor used, no significant change in caspase-3 functional activity was found in CHD cell lines. HRS cells infected with Ad5IkappaB also showed a marked increase in spontaneous apoptosis compared with wild type adenovirus-infected and control cells. Overall, the inhibition of active NF-kappaB in HRS cells resulting in spontaneous caspase-independent apoptosis demonstrates a critical role for NF-kappaB in HRS cell survival and resistance to apoptosis.

Primary papillary adenocarcinoma confined to the middle ear and mastoid

Primary adenocarcinoma is a rare tumor of the middle ear and temporal bone; its most frequent symptoms are hearing loss, otalgia, and facial paralysis. Otoscopic examination of a 27-year-old man revealed purulent discharge in the ear canal, diffuse edema, and hypertrophy of the right tympanic membrane. He presented with a grade III (House-Brachman) facial paralysis and right conductive hearing loss with a history of aural discharge for 6 months, otalgia, and facial weakness for 2 days. Computed tomography of the temporal bone showed an opacity filling the tympanic cavity, antrum, and aditus. Tympanotomy revealed diffuse edema of the middle ear mucosa, and granulation tissue was encountered during mastoidectomy filling the antrum and periantral cells and eroding the fallopian canal at the level of the oval window. After the histopathological examination revealed papillary adenocarcinoma, a subtotal temporal bone resection, facial nerve segmenter resection, and end-to-end anastomosis of the facial with the hypoglossal nerves were performed. The importance of histopathological examination in all cases of chronic otitis media with granulation tissue is stressed.

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

OBJECTIVE

Polymerase chain reaction amplification of DNA for T-cell receptor (TCR) gene rearrangement analysis is helpful in the evaluation of T-cell lymphoproliferative disorders. Detection of polymerase chain reaction products is limited by the poor resolution of bands analyzed by agarose or polyacrylamide gel electrophoresis. To improve the detection of a clonal T-cell population, we used temperature gradient gel electrophoresis (TGGE) as an alternative method for analysis of TCR gene rearrangement.

DESIGN

One hundred eighteen archival DNA samples were randomly selected based on previous Southern blot analysis results. Samples included 58 T-cell neoplasms with positivity for TCR beta gene rearrangement, 22 cases of reactive hyperplasia with germline pattern for both TCR beta and J(H), and 38 patients with B-cell lymphoma. MOLT-16, a T-cell lymphoblastic cell line, was used for the sensitivity assay. Polymerase chain reaction was performed using GC-clamped multiplex primers to amplify the TCR gamma locus and was analyzed by TGGE. The range of temperature gradients was empirically determined for optimal resolution of bands.

RESULTS

The sensitivity of TGGE was 0.1% when DNA from the MOLT-16 cell line was serially diluted with DNA from reactive lymphoid tissue. Fifty-four (93%) of 58 T-cell neoplasms with TCR beta gene rearrangements showed rearrangement patterns by TCR gamma TGGE, and only 1 of 60 samples (reactive or B-cell lymphomas) showed evidence of gene rearrangement by TGGE. Patients with T-cell neoplasm and involvement of multiple sites showed an identical migration pattern by TGGE analysis.

CONCLUSION

We demonstrate that TGGE is an effective method for analysis of TCR gene rearrangement in the evaluation of nodal and extranodal lymphoid lesions.

Expression of the tumor necrosis factor receptor-associated factors (TRAFs) 1 and 2 is a characteristic feature of Hodgkin and Reed-Sternberg cells

Tumor necrosis factor receptor-associated factors (TRAFs) are a recently established group of proteins involved in the intracellular signal transduction of several members of the tumor necrosis factor receptor (TNFR) superfamily. Recently, specific members of the TRAF family have been implicated in promoting cell survival as well as activation of the transcription factor NF-kappaB. We investigated the constitutive expression of TRAF1 and TRAF2 in Hodgkin and Reed-Sternberg (HRS) cells from archived paraffin-embedded tissues obtained from 21 patients diagnosed with classical Hodgkin's disease (HD). In a selective portion of cases, examination of HRS cells for Epstein-Barr virus (EBV)-encoded RNA was performed by in situ hybridization, and the results were compared with the magnitude of TRAF1 and TRAF2 staining. We also determined the TRAF profile in the classical HD cell lines L428, KMH2, and HS445 by Western blotting using a series of antibodies that specifically recognize the six individual TRAF family proteins (TRAF1-TRAF6). Moderate to high constitutive expression of TRAF1 and TRAF2 were found in 19 of 21 and 20 of 21 cases of classical HD, respectively. Of the remaining cases, one case showed weak expression of TRAF1, and another case showed weak expression of both proteins. No relationship was found between the staining intensity of the TRAF proteins and EBV expression in HRS cells. Strong constitutive expression of TRAF1 was also identified in the HD cell line L428, compared with the relatively weak expression observed in KMH2 and HS445. All three HD cell lines showed strong expression of TRAF2 protein and moderate, comparatively equal expression of TRAF4 and TRAF6. In contrast, TRAF3 was not expressed in the HD cell lines. Although KMH2 showed weak expression, the remaining HD cell lines also lacked TRAF5 protein. These data demonstrate that constitutive expression of TRAF1 and TRAF2 is a characteristic feature of HRS cells from both patient and cell line specimens. Furthermore, with the exception of TRAF1 expression, HRS cells from the three HD cell lines showed similar TRAF protein expression patterns. Overall, these findings demonstrate the expression of several TRAF proteins in HD. Significantly, the altered regulation of selective TRAF proteins may reflect HRS cell response to stimulation from the microenvironment and potentially contribute both to apoptosis resistance and cell maintenance of HRS cells.

Constitutive expression of NF-kappa B is a characteristic feature of mycosis fungoides: implications for apoptosis resistance and pathogenesis

The NF-kappa B family of transcription factors is an important regulator of genes expressed during inflammatory responses, immunoglobulin (Ig) class switching, cellular differentiation, and apoptosis. Recently, members of the NF-kappaB family, including p65(Rel A), have been implicated in promoting survival of various hematopoeitic neoplasms, including T cell malignancies such as adult T cell leukemia-lymphoma. We investigated the expression of active NF-kappa B p65(Rel A) in cases of mycosis fungoides (MF) and the effect of chemical inhibitors of NF-kappa B on apoptosis in cutaneous T cell lymphoma (CTCL) cell lines. Paraffin-embedded tissues from 23 cutaneous lesions and a single lymph node biopsy from patients diagnosed with MF were evaluated for p65(Rel A) expression by using a monoclonal mouse antibody that detects the activated form of p65(Rel A). Apoptosis after treatment with the NF-kappa B inhibitors gliotoxin, MG132, BAY 11-7082, and BAY 11-7085 was quantitatively measured in the CTCL cell lines HuT-78 and HH by propidium iodide (PI)/cell cycle analysis for detection of a hypodiploid (sub-G(0)) population and by determination of increased Annexin V/7-amino-actinomycin D (7-AAD) expression. Nuclear extracts from CTCL cells before and after chemical inhibition were analyzed for NF-kappa B nuclear DNA-binding activity by electrophoretic mobility shift assay (EMSA) with quantitative densitometry. Nuclear expression of p65(Rel A) before and after treatment with the various inhibitory compounds was measured by immunofluorescence staining in each CTCL cell line. Neoplastic T lymphocytes from 22 of 24 cases of MF showed strong nuclear and cytoplasmic expression of active p65(Rel A). Compared with untreated control cells, a marked increase in apoptosis, a significant decrease in NF-kappa B DNA-binding activity, and a marked decrease in nuclear p65(Rel A) expression were seen in cells from both CTCL cell lines after chemical NF-kappa B inhibition. These data show that the active form of NF-kappa B p65(Rel A) is commonly expressed in neoplastic T lymphocytes in patients with MF. In CTCL cell lines, the significant decrease in nuclear NF-kappa B expression and the marked increase in spontaneous apoptosis caused by chemical NF-kappa B inhibition suggest a critical role for NF-kappa B in the pathogenesis and tumor cell maintenance of CTCLs. HUM PATHOL 31:1482-1490.

Multiparameter immunohistochemical analysis of the cell cycle proteins cyclin D1, Ki-67, p21WAF1, p27KIP1, and p53 in mantle cell lymphoma

BACKGROUND

Mantle cell lymphoma (MCL) is characterized by overexpression of cyclin D1, a G1 cyclin that participates in the control of cell cycle progression at the G1 to S phase transition. In addition to cyclin D1, other cell cycle regulatory molecules may be involved in the proliferation and progression of MCL. Mutation of p53, deletion of p16(INK4a), and loss of p21(WAF1) expression have been reported in some cases of blastoid MCL.

OBJECTIVE

We sought to examine levels of expression of these proteins in typical and blastoid MCL and to determine whether differences were present between these subtypes of lymphomas.

DESIGN

A retrospective series of typical and blastoid MCLs was evaluated for expression of the cell cycle-related proteins cyclin D1, p21(WAF1), p27(KIP1), Ki-67, and p53, as well as mitotic index. Paraffin-embedded archival tissues from 24 MCL specimens (17 typical, 7 blastoid) were immunostained with antibodies to p21(WAF1), p27(KIP1), p53, Ki-67, and cyclin D1. The percentage of positive cells for each specimen was estimated by counting 1500 cells under oil immersion microscopy. Levels of antigen expression were compared for the typical and blastoid MCLs. The mitotic index was estimated using twenty 100x oil immersion fields (OIFs) for each specimen.

RESULTS

Cyclin D1 expression was seen in 22/24 specimens (92%). Blastoid MCLs were characterized by a significantly higher mean mitotic index (>20 mitoses/20 OIFs) and Ki-67 index (>45%) when compared with typical MCLs (P <.001 and P <.008, respectively; Fisher's exact test). High expression of p27(KIP1) (>25% staining) was seen more frequently in typical MCLs than in the blastoid variants (P =.03; Fisher's exact test). No significant differences were found between typical and blastoid MCLs for the expression of p21(WAF1) or p53.

CONCLUSIONS

A significantly higher mitotic index and Ki-67 index were found in blastoid MCLs as compared with typical MCLs. Low p27(KIP1) expression was associated with the blastoid MCL variant. These findings confirm the high proliferative nature of blastoid MCL and suggest a role for p27(KIP1) in the negative regulation of the cell cycle in MCL.

Characterization of apoptosis induced by protein kinase C inhibitors and its modulation by the caspase pathway in acute promyelocytic leukaemia

Acute promyelocytic leukaemia (APL;M3) is a unique form of acute myelogenous leukaemia characterized by t(15;17) translocation. The induction of apoptosis via inhibiting protein kinase C (PKC) has been recently viewed as a promising tool for the eradication of several malignant disorders. In the present study, we investigated the effect of two different protein kinase C inhibitors, Gö6976 and safingol, on the induction of apoptosis in the APL cell line NB4 and its all trans retinoic acid (ATRA)-resistant variant NB4.306. The effect of the PKC inhibitors on leukaemic cells obtained from three APL patients was also studied. We also evaluated the possible involvement of the caspases in apoptosis induced by PKC inhibitors. Significant time- and concentration-dependent apoptotic changes were demonstrated using Gö6976 and safingol. In addition, our results demonstrated that the caspases were involved in the apoptosis induced by the PKC inhibitors. In conclusion, our study illustrates that the PKC inhibitors Gö6976 and safingol induce apoptosis in APL and hence could be potential therapeutic agents for the treatment of this disease.

Immobilization of invertase in conducting thiophene-capped poly(methylmethacrylate)/polypyrrole matrices

Immobilization of invertase in thiophene-capped poly(methylmethacrylate)/polypyrrole matrices was achieved by constant potential electrolysis using different supporting electrolytes. Optimum reaction conditions such as substrate concentration, temperature, and pH for the enzyme electrodes were determined. The temperature and pH were found to be 60 degrees C and 4.8, respectively. The effect of supporting electrolyte on the enzyme activity revealed that SDS was the best in the immobilization procedure. Michaelis-Menten constant and the maximum reaction rate in PMMA/PPy matrices were of the order of that of pristine polypyrrole. However, in terms of repeated use, the copolymer matrices were superior to polypyrrole.

Mucosa-associated lymphoid tissue-type lymphomas occurring in post-transplantation patients

Post-transplantation lymphoproliferative disorders (PTLDs) are usually Epstein-Barr virus (EBV)-associated B-cell lymphoproliferative disorders that vary in their morphologic spectrum. Extranodal marginal zone lymphomas of the mucosa-associated lymphoid tissue-type (MALT-type) have not been considered to be part of this spectrum. The authors encountered five such cases recently. The clinical, histopathologic, and immunophenotypic features are reported. There were three men and two women with a mean age of 51.2 years (range, 48-63 years). Two patients were cardiac transplant recipients, two patients were liver transplant recipients, and the remaining patient was a renal transplant patient. Sites of lymphoma were the stomach in three patients and the parotid gland in two patients. Mean time to the lymphoma was 84 months after transplantation. All patients had morphologic features of low-grade extranodal marginal zone lymphomas of the MALT-type, and Helicobacter pylori was present in all three gastric cases. All patients exhibited the B-cell immunophenotype and were negative for EBV by in situ hybridization. These lymphomas were treated with a variety of modalities, including reduction of immunosuppression, antibiotics, surgical resection, radiation therapy, and chemotherapy. At last follow-up, one patient had developed signet ring adenocarcinoma at 27 months but had no evidence of PTLD, one patient relapsed at 17 months but is alive with stable disease at 24 months, and the remaining patients were alive without disease at 11, 12, and 14 months. Extranodal low-grade MALT-type lymphomas can occur in the post-transplantation setting and generally develop years after transplant. As seen in immunocompetent patients, EBV appears to play no role in the pathogenesis of these lymphomas. These lymphomas appear to have more in common with MALT-type lymphomas in nonimmunocompromised patients than conventional PTLDs, although they occur in "at-risk" patients due to their immunosuppressive therapy. These lymphomas do not appear to be clinically aggressive. Recognition of MALT-type lymphomas in the post-transplantation setting as an indolent disease avoids unnecessary treatment.

Simian virus 40 is present in most United States human mesotheliomas, but it is rarely present in non-Hodgkin's lymphoma

Simian virus 40 (SV40) causes mesotheliomas, osteosarcomas, ependymomas, choroid plexus tumors, and lymphomas in hamsters. In humans, SV40 has been detected in tumors of the first four types. Using the polymerase chain reaction (PCR), we tested 29 non-Hodgkin's lymphomas (intermediate and high-grade), 25 posttransplant lymphoproliferative disorders, and 5 AIDS lymphomas for SV40 DNA. PCR analysis revealed that 3 of 29 lymphomas, 6 of 25 posttransplant lymphoproliferative disorders, and 2 of 5 AIDS lymphomas contained SV40 sequences corresponding to the retinoblastoma (RB)-pocket binding domain of SV40 tumor antigen (Tag). However, among positive samples, only one posttransplant lymphoproliferative disorder and one AIDS lymphoma contained the SV40 regulatory region, which suggest a higher viral load in these patients. In parallel experiments, 8 of 12 mesotheliomas tested positive for SV40 for both the RB-pocket binding domain of Tag and the SV40 regulatory region. These data confirm the presence of SV40 in most United States mesotheliomas and indicate that in human non-Hodgkin's lymphomas, the prevalence of SV40 is low.

Bcl-6 protein expression by follicle center lymphomas. A marker for differentiating follicle center lymphomas from other low-grade lymphoproliferative disorders

Low-grade lymphoproliferative disorders are a heterogeneous group of lymphoid neoplasms with wide variation in histologic features, immunologic phenotype, and molecular abnormalities. Subclassification of these disorders with small lymphocytic proliferation may be difficult on the basis of morphologic findings alone. The bcl-6 gene, originally cloned from a tumor with 3q27 translocation, is commonly expressed in large cell lymphomas. In humans, bcl-6 encodes for a Krüppel-type zinc finger protein and is believed to be important in germinal center formation. Bcl-6 protein is expressed mainly by follicle center cells and a few interfollicular T lymphocytes. We analyzed Bcl-6 expression with immunologic methods in common low-grade lymphoproliferative disorders as an aid to differentiation of tumors with follicle center origin. We analyzed Bcl-6 staining of formalin-fixed paraffin-embedded tissue from 72 indolent lymphomas including 31 grade I and II follicle center lymphomas (FCL). 13 small lymphocytic lymphomas (SLL), 12 mantle cell lymphomas (MCL), and 16 marginal zone lymphomas (MZL) including lymphomas of mucosa-associated lymphoid tissue and spleen. All of 31 FCL were positive for Bcl-6 expression. One of 13 SLL and 1 of 12 MCL were positive, whereas none of 16 MZL were positive. Bcl-6 was also detected in 5 of 5 FCL and 1 of 3 MZL but in no SLL or MCL by Western blot analysis in 14 cases with lymphoid disorders. Our study demonstrates that Bcl-6 expression is common in low-grade FCL but is rare in other indolent B-cell lymphoid disorders, and may be a useful adjunct in classification of indolent lymphomas.

High-level variability in the ORF-K1 membrane protein gene at the left end of the Kaposi's sarcoma-associated herpesvirus genome defines four major virus subtypes and multiple variants or clades in different human populations

Infection with Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) or human herpesvirus 8 (HHV8) is common in certain parts of Africa, the Middle East, and the Mediterranean, but is rare elsewhere, except in AIDS patients. Nevertheless, HHV8 DNA is found consistently in nearly all classical, endemic, transplant and AIDS-associated KS lesions as well as in some rare AIDS-associated lymphomas. The concept that HHV8 genomes fall into several distinct subgroups has been confirmed and refined by PCR DNA sequence analysis of the ORF-K1 gene encoding a highly variable glycoprotein related to the immunoglobulin receptor family that maps at the extreme left-hand end of the HHV-8 genome. Among more than 60 different tumor samples from the United States, central Africa, Saudi Arabia, Taiwan, and New Zealand, amino acid substitutions were found at a total of 62% of the 289 amino acid positions. These variations defined four major subtypes and 13 distinct variants or clades similar to those found for the HIV ENV protein. The B and D subtype ORF-K1 proteins differ from the A and C subtypes by 30 and 24%, respectively, whereas A and C differ from each other by 15%. In all cases tested, multiple samples from the same patient were identical. Examples of the B subtype were found almost exclusively in KS patients from Africa or of African heritage, whereas the rare D subtypes were found only in KS patients of Pacific Island heritage. In contrast, C subtypes were found predominantly in classic KS and in iatrogenic and AIDS KS in the Middle East and Asia, whereas U.S. AIDS KS samples were primarily A1, A4, and C3 variants. We conclude that this unusually high diversity, in which 85% of the nucleotide changes lead to amino acid changes, reflects some unknown powerful biological selection process that has been acting preferentially on this early lytic cycle membrane signalling protein. Two distinct levels of ORF-K1 variability are recognizable. Subtype-specific variability indicative of long-term evolutionary divergence is both spread throughout the protein as well as concentrated within two 40-amino-acid extracellular domain variable regions (VR1 and VR2), whereas intratypic variability localizes predominantly within a single 25-amino-acid hypervariable Cys bridge loop and apparently represents much more recent changes that have occurred even within specific clades. In contrast, numerous extracellular domain glycosylation sites and Cys bridge residues as well as the ITAM motif in the cytoplasmic domain are fully conserved. Overall, we suggest that rather than being a newly acquired human pathogen, HHV8 is an ancient human virus that is preferentially transmitted in a familial fashion and is difficult to transmit horizontally in the absence of immunosuppression. The division into the four major HHV8 subgroups is probably the result of isolation and founder effects associated with the history of migration of modern human populations out of Africa over the past 35,000 to 60,000 years.

Characterization of the interleukin-1beta-converting enzyme/ced-3-family protease, caspase-3/CPP32, in Hodgkin's disease: lack of caspase-3 expression in nodular lymphocyte predominance Hodgkin's disease

Apoptosis (programmed cell death) serves an important role in the normal morphogenesis, immunoregulation, and homeostatic mechanisms in both normal and neoplastic cells. Caspase-3/CPP32, a member of the ICE/Ced-3-family of cysteine proteases, is an important downstream mediator of several complex proteolytic cascades that result in apoptosis in both hematopoietic and nonhematopoietic cells. Previous studies have demonstrated that caspase-3 is commonly expressed in classical Hodgkin's disease (CHD); however, the biological significance of its expression in Hodgkin's disease is unknown. In this report, the expression of caspase-3 in nodular lymphocyte predominance Hodgkin's disease (NLPHD) was evaluated by immunohistochemistry; in addition, we investigated the role of caspase-3 in CD95 (Fas)-mediated apoptosis in three CHD cell lines. Formalin-fixed, paraffin-embedded tissue sections from 11 cases of NLPHD were immunostained for caspase-3 using a polyclonal rabbit antibody that detects both the 32-kd zymogen and the 20-kd active subunit of the caspase-3 protease. Only 1/11 cases of NLPHD demonstrated caspase-3 immunopositivity in lymphocytic/histiocytic cells. Caspase-3 expression was also evaluated in three CHD cell lines, HS445, L428, and KMH2. Whereas caspase-3 expression was detected in HS445 and L428 cell lines, no expression was found in KMH2 cells by immunohistochemical staining. Treatment of HS445 and L428 cell lines for 72 hours with agonistic CD95 monoclonal antibody induced marked apoptosis that was significantly inhibited by pretreatment with the caspase-3 inhibitor, DEVD-FMK, as determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay and flow cytometric analysis of 7-amino-actinomycin D staining. In addition, a significant increase in caspase-3 activity as determined by an enzyme colorimetric assay was detected in HS445 and L428 cells after 48 hours of CD95 stimulation. In marked contrast, treatment of caspase-3-deficient KMH2 cells with anti-CD95 mAb did not demonstrate an increase in caspase-3 activity or induce apoptosis. These data demonstrate caspase-3 is important for CD95-mediated apoptosis in CHD cell lines. In addition, the majority of NLPHD cases examined in this study failed to express detectable levels of caspase-3, suggesting these tumor cells may be resistant to apoptotic stimuli dependent on caspase-3 activity. Furthermore, these data suggest the differential expression of caspase-3 noted between NLPHD and CHD may provide additional evidence that each is a unique disease entity.

Usefulness of molecular detection of human herpesvirus-8 in the diagnosis of Kaposi sarcoma by fine-needle aspiration

Kaposi sarcoma (KS), a multifocal angioproliferative disorder, occurs most commonly in patients with AIDS, in whom it remains an important cause of morbidity and mortality. KS is often in the differential diagnosis in HIV-infected patients undergoing fine-needle aspiration (FNA). FNA diagnosis of KS is usually made by morphologic observation of scant tissue fragments composed of bland spindle cells and crush artifact. Human herpesvirus-8 (HHV-8) has been identified by polymerase chain reaction (PCR) amplification of DNA samples isolated from various epidemiologic forms of KS. In an attempt to improve the accuracy of KS diagnosis by FNA, we analyzed for the presence of HHV-8 DNA in 13 spindle-cell lesions evaluated by FNA: KS, 8 cases; granulomatous inflammation due to Mycobacterium avium-intracellulare, 1; nodular fasciitis, 1; dermatofibrosarcoma protuberans, 1; dermatofibroma, 1; benign spindle-cell lesion of nerve sheath origin, 1; and 2 lesions with lymphoid hyperplasia. DNA isolated from archival Wright-Giemsa-stained glass slides was used for the PCR amplification of the HHV-8 DNA sequences. All of the cases diagnosed as KS and 1 of the lymphoid hyperplasia cases were PCR-positive for HHV-8 DNA, while all other cases of spindle-cell lesions were negative. The molecular demonstration of HHV-8 DNA may be a useful adjunct in the diagnosis of KS by FNA.

Usefulness of an immunohistochemical panel in paraffin-embedded tissues for the differentiation of B-cell non-Hodgkin's lymphomas of small lymphocytes

Diagnosis of small B-cell lymphomas is sometimes difficult without fresh tissue for flow cytometry (FC) or immunohistochemistry (IHC). Therefore, we examined the usefulness of a paraffin section IHC panel consisting of antibodies to CD5, CD10, CD20, CD23, CD43, and cyclin D1. We tested 55 formalin-fixed small B-cell lymphomas, including 16 small lymphocytic lymphomas (SLLs), 10 mantle cell lymphomas (MCLs), 25 follicle center lymphomas (FCLs), and 4 mantle zone lymphomas (MZLs). Seventeen cases had B5-fixed sections that were stained in the same manner. The findings were correlated with FC immunophenotyping when available. All of the SLLs and 90% of the MCLs expressed CD5 by IHC, with occasional weak expression in some MCLs. All of the FCLs and MZLs lacked CD5 expression. These results were comparable to those obtained by FC. CD43 expression was seen in 100% of the SLLs, 90% of the MCLs, and 75% of the MZLs. CD23 expression was seen in 94% of the SLL; of these, 100% also showed expression of CD23 by FC. Cyclin D1 was detected in all of the MCLs by IHC but also in 3 of the 16 SLLs. CD23 was absent in all of the MCLs. CD10 expression was present in 21 (95%) of 22 FCLs. All of the 17 cases fixed in B5 showed a decreased immunoreactivity for CD5 in the neoplastic cells. In contrast, CD10 immunoreactivity was judged better in B5-fixed sections. We concluded, therefore, that anti-CD5 and -CD10 were useful tools in the differential diagnosis of B-cell lymphomas of small lymphocytes and that a paraffin-section IHC panel consisting of antibodies to CD5, CD10, CD20, CD23, CD43, and cyclin D1 was a useful ancillary technique that compared favorably with FC.

Monoclonal IgH gene rearrangement in microdissected nodules from nodular sclerosis Hodgkin disease

Recently, single-cell PCR studies have demonstrated that Hodgkin and Reed-Sternberg (HRS) cells are clonally related in many cases of Hodgkin disease. To investigate the lineage and clonality of neoplastic cells in local environments in nodular sclerosis Hodgkin disease (NSHD), we microdissected multiple distinct nodules from patients with NSHD and analyzed them for IgH gene rearrangement by PCR. These results were correlated with immunophenotype, Epstein-Barr-encoded RNA (EBER) expression, and clinical outcome. Forty individual nodules from 10 patients with NSHD (11 specimens) were microdissected from formalin-fixed paraffin-embedded tissue. DNA extracts were analyzed for IgH gene rearrangement by using PCR with FRIIIa and JHa primers. Cases were immunophenotyped in paraffin sections with antibodies to CD20(L26), CD79a(HM57), CD45RO(A6), CD15 (Leu-M1), and CD30(Ber-H2). Infection of HRS cells by Epstein-Barr virus was evaluated by using EBER in situ hybridization (EBER-ISH). DNA extracts from 12 of 40 microdissected nodules from 8 of 10 patients demonstrated a monoclonal pattern by IgH-PCR. Three patients demonstrated 2 individual nodules with different monoclonal patterns. One patient demonstrated 2 nodules with bands that appeared similar in size but were found to be different from one another upon further testing. All 28 remaining nodules demonstrated a polyclonal pattern. Six of 10 patients were positive for the Epstein-Barr virus genome by EBER-ISH. No correlation was found between IgH monoclonality, immunophenotypic features, Epstein-Barr virus infection, or clinical outcome. It was concluded that a subset of NSHD cases contain detectable monoclonality within individual nodules by IgH-PCR, suggesting that HRS cells are clonally related within local microenvironments.

Immunohistochemical analysis of mycosis fungoides on paraffin-embedded tissue sections

Mycosis fungoides (MF) is typically characterized by dermal and epidermal infiltration of T lymphocytes with a helper/inducer phenotype. Immunophenotypic analysis of such cases was traditionally performed by flow cytometry or immunohistochemistry on cryostat sections. With the advent of new monoclonal antibodies developed against T-cell antigens, including CD3, CD4, CD5, and CD8, it is now possible to immunophenotype T-cell subpopulations in paraffin-embedded tissues. To investigate the potential use of these antibodies for the evaluation of cutaneous lesions, 35 specimens (34 skin and 1 lymph node) from 29 patients with MF were retrospectively reviewed and immunophenotyped in paraffin sections with antibodies to CD3 (T-cell CD3), CD4 (NCL-CD4-1F6), CD5 (NCL-CD5-4C7), CD8 (CD8/144B), and CD20 (L26). Epidermal and dermal distribution of T and B cells were analyzed, and we assessed the ratios of CD4+ to CD8+ T cells. All of our 35 cases demonstrated a predominant CD3+ T-cell population. In 32 cases, the neoplastic cells expressed CD3, CD4, and CD5 consistent with a T-helper/inducer phenotype. In three cutaneous cases, the neoplastic CD4+ T cells showed minimal or absent expression of CD5, indicating an aberrant phenotype. In the majority of cases, minimal CD8+ T cells were present in the background, but in four cases, the CD4:CD8 ratios were 2:1 or less. Thirty-two cutaneous cases demonstrated epidermotropism exclusively by CD4+ T cells; one case showed both CD4+ and CD8+ T cells. In 17 cutaneous cases, scattered dermal CD20+ B cells were found individually or in small clusters within the background surrounding the neoplastic infiltrates. We concluded, therefore, that the immunophenotypic analysis of T-cell subpopulations using monoclonal antibodies of CD3, CD4, CD5, and CD8 was useful for histologic evaluation and confirmation of MF lesions in paraffin-embedded tissue. These antibodies might also provide an effective method of immunophenotyping other neoplastic and non-neoplastic T-cell populations in paraffin-embedded tissues.

Geographically distinct HHV-8 DNA sequences in Saudi Arabian Iatrogenic Kaposi's sarcoma lesions

A new member of the gamma-herpesvirus family, HHV-8 (also known as Kaposi's sarcoma (KS)-associated herpesvirus), has been linked to KS and body cavity-based lymphoma. Other members of this family, eg, Epstein-Barr virus, were originally thought to have only one strain, but subsequent analysis revealed different strains correlating to cellular patterns of infectivity and geographical location. To determine whether multiple strains of HHV-8 exist, we compared DNA sequences among KS and body cavity-based lymphoma-derived HHV-8 and examined differences in HHV-8 subgroups between American and Saudi Arabian iatrogenic KS patients. Samples were analyzed by polymerase chain reaction using multiple primer sets to five different open reading frames from HHV-8, and DNA sequencing was performed. HHV-8 DNA was present in all of our KS and body cavity-based lymphoma samples by polymerase chain reaction. HHV-8 DNA was detected in each body cavity-based lymphoma sample using a majority of the primers, whereas only two primer sets consistently amplified HHV-8 DNA derived from KS lesions. DNA sequencing within open reading frames 26 and 27 indicate the existence of at least three variants of HHV-8, with the majority of iatrogenic KS patients in Saudi Arabia containing unique nucleotide changes that may define a distinct, previously unidentified subgroup we term SA, whereas those from America were of Group A or B. Thus, although the sequencing data within open reading frames 26 and 27 did not permit discrimination between patients with lymphoma versus KS disease processes, HHV-8 derived from Saudi Arabian KS lesions were shown to have a distinct nucleotide sequence not seen in any of the other clinical samples examined.

Post-transplantation lymphoproliferative disorder of the NK-cell type: a case report and review of the literature

Post-transplantation lymphoproliferative disorders (PTLDs) are primarily B-cell disorders that are thought to be Epstein-Barr virus (EBV) driven and that can occur months to years after solid organ or bone marrow transplantation. A small percentage of cases have also been shown to be T-cell phenotype, but a PTLD of NK-cell type has not been previously described. We report here the case of a renal transplant recipient in whom a clinically aggressive, histologically monomorphic PTLD developed that was documented to be of an NK-cell phenotype according to paraffin section and flow cytometric immunophenotyping. Molecular-genetic analysis showed the PTLD to contain germline immunoglobulin heavy, kappa light chain, and T-cell receptor beta and gamma genes. Studies for EBV failed to demonstrate the presence of viral infection in tumor cells. Clinical follow-up showed a rapidly fatal course. To our knowledge, this is the first reported case of an EBV-negative PTLD of true NK-cell type.

Molecular and pathologic characterization of an AIDS-related body cavity-based lymphoma, including ultrastructural demonstration of human herpesvirus-8: a case report

Body cavity-based lymphoma, also known as primary effusion lymphoma, is a newly recognized acquired immunodeficiency syndrome (AIDS)-related lymphoma that has been linked to the Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8). To date, direct visualization of the virus in a clinical sample has not been demonstrated. We have performed an extensive clinical, histologic, immunophenotypic, ultrastructural, and molecular genetic correlative study on multiple tissue samples obtained premortem and at autopsy from an patient with AIDS with Kaposi's sarcoma and body cavity-based lymphomas. We demonstrate the presence of human herpesvirus-8 in a primary clinical sample at the ultrastructural and molecular level, as well as document multiple lymphomatous tumor masses at autopsy.