Human immunodeficiency virus-related lymphoma: relation between clinical features and histologic subtypes.

PURPOSE: Non-Hodgkin's lymphoma occurs frequently in patients with human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS). We determined the association between the clinical and histologic features of HIV-related lymphoma. SUBJECTS AND METHODS: We reviewed the medical records of 291 patients with noncerebral HIV-related lymphoma who had been treated in multicenter trials coordinated by the Groupe d'Etude des Lymphomes de l'Adulte between 1988 and 1997. This study was performed mainly before the availability of combination antiretroviral therapy. RESULTS: The main histologic subtypes were centroblastic lymphoma in 131 patients (45%), immunoblastic lymphoma in 39 patients (13%), and Burkitt's lymphoma (including the classical form and the variant with plasmacytic differentiation) in 115 patients (40%). Burkitt's lymphoma was the most aggressive form, whereas immunoblastic lymphoma occurred in severely immunodeficient patients. Two-year survival after enrollment was 15% in immunoblastic lymphoma, 32% in Burkitt's lymphoma, and 31% in centroblastic lymphoma (P = 0.006), but multivariate analysis did not confirm the independent prognostic value of histologic subtype. Instead, five independent pretreatment factors increased the risk of mortality: age 40 years or older [relative risk (RR) = 1.5; 95% confidence interval (CI), 1.1 to 2.1; P = 0.005], elevated serum lactate dehydrogenase level (RR = 1.5; 95% CI, 1.1 to 2.1; P = 0.02), having a diagnosis of AIDS before lymphoma (RR = 1.8; 95% CI, 1.2 to 2.6; P = 0.006), CD4(+) cell count less than 100 x 10(6)/L (RR = 1.8; 95% CI, 1.3 to 2.6; P = 0.0004), and impaired performance status (RR = 2.4; 95% CI, 1.7 to 3.4; P <0.0001). CONCLUSION: Several pretreatment characteristics of HIV-related lymphoma were linked to the histologic form, but HIV disease parameters other than those of lymphoma were the main determinants of outcome, so the histologic features of the lymphoma were not associated with prognosis.

The management of adult aggressive non-Hodgkin's lymphomas.

Aggressive non-Hodgkin's lymphona include diffuse large B-cell lymphoma, anaplastic large cell lymphona, and different peripheral T-cell lymphomas. An international prognostic index has been developed including age, serum LDH, performance status, and extranodal involvement. For localized aggressive lymphoma, the preferred treatment is 3-4 CHOP and radiation therapy, with a cure rate of 70-80%. For disseminated aggressive lymphoma, current regimens have a cure rate of less than 40%. Innovative strategies, including dose escalation, autologus stem cell support, new drugs, and immunotherapy are being explored to improve these results.

Detection of the cell death-inducing protein BAK in Reed-Sternberg cells of Hodgkin's disease.

The expression of the cell death-inducing protein, Bak, was investigated in 41 cases of Hodgkin's disease and was correlated with Epstein-Barr virus (EBV) status. Overall, Bak immunostaining was observed in 35/41 cases (85%). Among the 22 EBV-positive cases, 20 cases (91%) expressed Bak while 15/19 EBV-negative cases (79%) contained Bak-positive Reed-Sternberg cells. The expression of Bak, as assessed by the staining intensity and the numbers of positive tumor cells, varied greatly from case to case but was high in 6 cases (15%). Our findings show that, similar to Bax, a second apoptosis-inducing gene Bak is frequently expressed in Hodgkin's disease. Whilst Bak is suspected to protect cells immortalized by EBV from apoptosis, its expression in Hodgkin's disease appears to be unrelated to the EBV status of Reed-Sternberg cells. Moreover, the potential pro-apoptotic functions related to Bak and Bax in Hodgkin's disease might be surpassed by a stronger expression of anti-apoptotic molecules thus explaining tumor progression.

Expression of apoptosis regulatory proteins of the Bcl-2 family and p53 in primary resected non-small-cell lung cancer.

Proteins of the Bcl-2 family as well as p53 are important regulators of apoptosis. Alterations in the expression of these proteins can contribute to the formation of cancer, as well as influence tumour response to chemo- and radiotherapy. We used antibodies specific for the human Bcl-2, Mcl-1, Bax, Bak and p53 proteins to examine the expression of these apoptosis-regulating genes in 49 archival specimens of patients with radically resected non-small-cell lung cancer (NSCLC). Tumour cells containing immunostaining for the antiapoptotic proteins Bcl-2 and Mcl-1 were present in 31% and 58% of the cases evaluated, respectively, whereas immunopositivity for the proapoptotic proteins Bax and Bak was found in 47% and 58% of the samples. p53 immunopositivity was detected in 61% of the samples. The expression of Bcl-2 and p53 and the expression of Mcl-1 and Bax showed a positive association (P = 0.02 and P = 0.06 respectively), whereas the expression of Bax was inversely related to p53 (P = 0.008). The expression of Bcl-2 had a negative influence on relapse-free survival in this population of primary resected NSCLC patients (P = 0.02). The expression of p53 and Bcl-2 was significantly associated with metastasis-free survival (P < 0.01). Only patients with p53-positive tumours developed metastases during the follow-up period. Our results establish the frequent expression of the Bcl-2 family proteins Bcl-2, Mcl-1, Bax and Bak in NSCLC. It can be expected that Bcl-2 family members have no straightforward impact on clinical outcome in this disease because their interactions in the regulation of apoptosis are complex.

High Epstein-Barr virus serum load and elevated titers of anti-ZEBRA antibodies in patients with EBV-harboring tumor cells of Hodgkin's disease.

Hodgkin's disease is commonly associated with EBV latent infection. The incidence of EBV reactivation (active infection or EBV infection with replicative cycle) was evaluated in a series of 30 patients with untreated Hodgkin's disease (except for one case with chronic lymphocytic leukemia) by quantitation of EBV DNA and titration of anti-ZEBRA antibodies in serum samples. DNA was detected in serum (>2.5 x 10(2) genomes/ml) in 15 of 30 patients and was more frequent in Hodgkin's disease with EBV-positive Reed-Sternberg cells (10/12) than in EBV-negative cases (5/18), (P< 0.01). Of interest was the demonstration that viremia correlated well with increased titers of anti-ZEBRA IgG and/or standard serological profiles of EBV reactivation (12/15), (P < 0.05). However the lack of EBV replicative cycle in Reed-Sternberg cells (negative for ZEBRA antigen and early antigen BHLF1) suggests that the viral replication occurs in a nonneoplastic cell compartment rather than in tumor cells. The measurement of EBV DNA loads and the titration of anti-ZEBRA antibodies shed new lights on the link between activation of EBV replication and Hodgkin's disease: these serological markers together with the determination of the EBV status of the tumor suggest that replication of the viral genome occurs with a decreased efficiency of the immune system, thus allowing progression of the tumor.

Location of the BCR-ABL fusion gene on the 9q34 band in two cases of Ph-positive chronic myeloid leukemia.

Two new variant Philadelphia (Ph) chromosomes with an aberrant location of the BCR-ABL fusion gene on 9q34 of the derivative 9 are reported. One presented cytogenetically as a standard t(9;22)(q34;q11), whereas the other was classified as an ins(9;22)(q34;q11.1q11.2) using the combined interpretation of cytogenic, FISH, and molecular data. The mechanisms of the two rearrangements are presented. It is suggested that the insertion has occurred in a single event in the patient with ins(9;22). In the patient with t(9;22), both a translocation and an insertion, occurring either sequentially or simultaneously, can account for the location of the BCR-ABL fusion gene on the derivative 9. A possible poor prognostic impact of this aberrant location of the BCR-ABL is also suggested by the clinical data reported in such patients.

Telomerase activity in reactive and neoplastic lymphoid tissues: infrequent detection of activity in Hodgkin's disease.

We used the recently described sensitive and rapid detection assay called telomeric repeat amplification protocol (TRAP) to detect telomerase activity in lymphoblastoid (n = 5) and lymphoma cell lines (n = 7), hyperplastic lymph nodes (n = 6) and tonsils (n = 5), and tissues involved by non-Hodgkin's lymphoma (NHL) (n = 43) and Hodgkin's disease (HD) (n = 14). Clearly evident telomerase activity was found in all lymphoblastoid and lymphoma cell lines, and in 34 of 43 cases (80%) of NHL. These results were expected because of the proliferative and immortal nature of the cell lines and most malignant cells. However, positive results were obtained with the TRAP assay in all hyperplastic lymph nodes and tonsils, which raises the issue of derepression of telomerase activity during an immune response. Telomerase activity alone therefore does not distinguish malignant lymphoid proliferations from reactive states. Telomerase activity was detected in only 1 of 14 cases (7%) of lymphoid tissues involved by HD. Eight of the 13 negative cases were considered to be interpretable because of the lack (3 of 13 cases) or low level (5 of 13 cases) of telomerase inhibition. The five remaining cases could not be evaluated because of their telomerase inhibitor content. The findings imply either transient or very low levels of telomerase activity in HD or that HD for the greater part is a telomerase-independent neoplasm. Microdissection studies are needed to identify subsets of cells carrying telomerase activity in both reactive and neoplastic lymphoid tissues.

Oligonucleotide clonospecific probes directed against the junctional sequence of t(14;18): a new tool for the assessment of minimal residual disease in follicular lymphomas.

Follicular lymphomas are often associated with t(14;18) chromosomal translocation. The rearrangement site (bcl-2/JH junctional region) between the two chromosomes is hypervariable regarding its size and DNA sequence, and is a potential specific marker for the neoplastic clone of each patient. We report the use of the polymerase chain reaction (PCR) technique for detecting and sequencing clonal bcl-2/JH rearrangements in lymph nodes and/or bone marrow specimens from patients with follicular lymphoma. 53 patients at diagnosis (n = 40) or at relapse (n = 13) were studied. 25 of these 53 cases were found to have the t(14;18) translocation involving either the major breakpoint region (MBR) (n = 21) or the minor cluster region (mcr) (n = 4). Since our PCR technique could detect the translocation in 1/10(6) cells we had to distinguish malignant cells from possible t(14;18)-bearing non-malignant cells which could be present during and after treatment. The bcl-2/JH junctional regions were therefore sequenced in order to synthesize an anti-junction oligonucleotide probe specific for each patient's malignant clone (clonospecific probe). Using these clonospecific probes for hybridization it was possible to detect one malignant cell mixed with 10(6) normal cells. 28 patients with advanced stage (stage III and IV), had been enrolled for treatment with myeloablative chemoradiotherapy and autologous bone marrow transplantation (ABMT). In 12 of these patients bcl-2/MBR translocation was found at diagnosis and used as a marker to detect the presence of residual lymphoma cells in serial bone marrow (BM) and peripheral blood (PB) samples. In three relapsed patients (with available tissue samples at diagnosis and relapse), clonospecific probes clearly demonstrated the same bcl-2/JH junction, thus confirming that the relapse occurred from the same malignant clone, and which remained stable without any clonal evolution of its junctional region throughout the course of the disease. These results demonstrate the value of the t(14;18) clonospecific probes as a diagnostic tool in the detection of minimal residual disease and relapses in patients with follicular lymphoma.

Bcl-x gene expression in Hodgkin's disease.

Bcl-x is a Bcl-2-family protein that has been previously detected in cortical thymocytes, plasma cells, and activated lymphocytes. We report here on the high detection rate of the Bcl-x protein found in 86% of Hodgkin's disease samples and on the significance regarding its complex role among the Bcl-2-family of proteins: Bcl-x is known to heterodimerize with Bcl-2 (an anti-apoptosis protein) and with Bax, a potent inducer of cell death. Moreover, recent evidences show that Bcl-x may induce multiple drug resistance in vitro, suggesting that chemical or biological interactions with this protein may have potential therapeutic value in Hodgkin's disease.

Primary mediastinal large B-cell lymphoma. A clinicopathologic study of 141 cases compared with 916 nonmediastinal large B-cell lymphomas, a GELA ("Groupe d'Etude des Lymphomes de l'Adulte") study.

Among non-Hodgkin's lymphomas, primary mediastinal large B-cell lymphoma (PMLCL) has been considered a separate entity that has specific clinical and histological aspects and a poor prognosis. In this study, we reexamined the clinicopathologic features and the response to current treatment of 141 PMLCL and compare them with 916 nonmediastinal large B-cell lymphomas (NMLCL) recorded in the same period and treated with similar combined chemotherapy. The clinical features of PMLCL at diagnosis were largely homogeneous and distinct from NMLCL, with a predilection for young women (59% with a mean age of 37 years versus 42% with a mean age of 54 years), bulky tumor (77% versus 7%, p < 10(4)), high serum lactic dehydrogenase (LDH) level 76% versus 51%, p < 10(4)), and frequent intrathoracic extension to adjacent organs such as pleura, pericardium, and lung. By contrast, extrathoracic or hematologic dissemination was uncommon (2% of bone marrow involvement versus 17%). All patients had diffuse large B-cell nonimmunoblastic, nonanaplastic lymphomas. Histological analysis of the 141 PMLCL evaluated two common patterns: the presence of large cells with clear cytoplasm (found in 38% of cases) and the presence of fibrosis (marked in 25% of cases). The presence of clear cells or intense fibrosis did not constitute prognostic indicators. Immunologic and molecular analysis assessed the profile of bcl-2 expression and the presence of Epstein-Barr virus (EBV) in PMLCL: 30% expressed a high level of bcl-2 protein; EBER RNAs were detected by in situ hybridization in only two of the 41 cases tested. Monotypic light chain restriction could be demonstrated in seven of the 41 PMLCL tested on fixed-section. Treated with polychemotherapy regimens without radiotherapy, 79% of PMLCL patients achieved a complete remission compared with 68% in the NMLCL patient group (p = 0.01). Overall, 3-year survival rates were estimated at 66 and 61%, respectively (p = 0.05), and disease-free survival rates were not significantly different (61 versus 64%). Stratified analysis on the International Prognostic Index (based on age, tumor stage, serum LDH level, and performance status) showed no difference in the overall and disease-free survivals between the two lymphoma groups. In conclusion, PMLCL can be combined with other diffuse large B-cell lymphomas on morphologic grounds; it is not associated with EBV. It responds favorably to treatment and should be managed like other high-grade lymphomas of equivalent histology. However, the uncommon clinical presentation makes it a distinct entity.

Expression of the cell death-inducing gene bax in carcinomas developed from the follicular cells of the thyroid gland.

The expression of apoptosis-regulating proteins, Bcl-2, Bax, Mcl-1, and Bcl-X, was evaluated by immunohistochemical methods in 39 cases of thyroid carcinomas. Normal thyroid tissues showed a consistent expression of Bcl-2 and Mcl-1 whereas Bax and Bcl-X proteins were essentially absent from most follicular thyroid cells. Bax expression was observed in all papillary carcinomas (n = 23) and in 8 of 10 follicular carcinomas. The intensity of Bcl-2 immunostaining was generally higher in follicular tumors (n = 10) than in papillary carcinomas (n = 21 of 23). However, in undifferentiated tumors, both Bax and Bcl-2 were weakly expressed. Mcl-1 protein expression was similar to that of Bax in papillary and follicular tumors, but was also frequently detectable in undifferentiated tumors. Bcl-X immunostaining was seen in all undifferentiated tumors (n = 6), in 22 of 23 papillary tumors, and in 5 of 10 follicular tumors. Our findings show that the regulation of bcl-2 family gene expression is different in normal thyroid tissue compared to that of its neoplastic counterpart and varies with the tumor subtype. In particular, unlike normal thyroid epithelium, the apoptosis-blocking gene bcl-X and the apoptosis-inducing gene bax are frequently expressed in thyroid carcinomas derived from the follicular cells. Thus, alterations in the expression of these bcl-2 family genes may contribute to the pathogenesis of thyroid carcinomas.

Immunodetection of apoptosis-regulating proteins in lymphomas from patients with and without human immunodeficiency virus infection.

The expression of the apoptosis-regulating genes Bcl-2, Bcl-x, Bax, Mcl-1, and p53 analyzed in 4 cases of human immunodeficiency virus (HIV)-associated Hodgkin's disease, in 36 cases of HIV-related non-Hodgkin's lymphomas (NHLs), and in 109 cases of non-HIV-related NHLs by using immunohistochemistry. HIV-associated Hodgkin's disease samples were positive for all markers. For the HIV-related NHL samples, 36, 66, 88, 100, and 94% of the cases were Bcl-2, Bcl-x, Bax, Mcl-1, and p53 were found to be expressed in 69, 65, 82, 83, and 42%, respectively. No significant differences were observed in Bax and Mcl-1 staining between HIV-unrelated NHLs of B cell and T cell types. In contrast, Bcl-2 was positive in 66/79 (83%) and 10/30 (33%) of B cell and T cell HIV-unrelated NHLs, respectively (P2 < 0.001). Peculiar patterns were observed for hairy cell leukemia (Bax+, Bcl-2+, Mcl-1-) and for anaplastic large cell lymphoma (Bax+, Mcl-1+, Bcl-2-) in HIV-unrelated NHLs. Of interest, all cases with a positive expression of Bax were also found to express either Mcl-1 and/or Bcl-2, suggesting that Mcl-1 and Bcl-2 may counteract the pro-apoptosis function of Bax in vivo by protein-protein interaction within the tumor cell, as demonstrated previously in vitro. These results suggest that apoptosis regulation may have a role in the pathogenesis of some HIV-related and HIV-unrelated NHLs.

Hodgkin's disease following mycosis fungoides: phenotypic and molecular evidence for different tumour cell clones.

AIMS: (1) To assess the clonality of tumour cells in two patients with mycosis fungoides who subsequently developed Hodgkin's disease; and (2) to determine whether there is a clonal relation between these two disorders. METHODS: Cutaneous tissue samples involved by mycosis fungoides and lymph nodes involved by Hodgkin's disease from both patients were investigated by immunohistochemistry and the polymerase chain reaction. RESULTS: Mycosis fungoides tumour cells in both patients expressed multiple T cell associated antigens; Reed-Sternberg (RS) cells had the null phenotype. T cell receptor gamma chain genes were clonally rearranged in mycosis fungoides cells but not in RS cells, including variants, in both patients. In the patient with intermediate transformation to large cell lymphoma, immunoglobulin heavy chain genes were rearranged in the cutaneous tumour, but not in the lymph node involved by Hodgkin's disease. CONCLUSION: The divergent antigen expression and gene rearrangements observed in these two patients strongly suggest that Hodgkin's disease and mycosis fungoides are not derived from a single tumour cell clone.

Characterization of Epstein-Barr virus-infected cells in benign lymphadenopathy of patients seropositive for human immunodeficiency virus.

The authors investigated 25 benign lymph nodes in patients infected with the human immunodeficiency virus (HIV) by in situ hybridization (ISH) and immunohistochemistry (IHC) to detect and characterize the Epstein-Barr virus (EBV)-infected cells. After ISH, 22 lymph nodes were found to contain various numbers of Epstein-Barr-encoded RNA (EBER)-positive cells. Most of these cells were B cells. In six lymph nodes with numerous EBV-infected cells, EBNA2-positive/LMP1-positive lymphoblastoid cells were detected by IHC. Exceptional cells (in two specimens) were positively labeled with antigen-Z Epstein-Barr replicative activator (ZEBRA) antibody or BamHI Left Frame 1/Not I (BHLF1/Not I) probes, indicating that EBV replication is not enhanced in the lymphocytes. In normal conditions (healthy individuals), small lymphocytes that express a restricted pattern of viral genes do escape immune response, whereas lymphoblastoid cells do not. Thus, impaired immune system may account for the late proliferation of lymphoblastoid cells (Epstein-Barr nuclear antigen [EBNA]2positive/latent membrane protein [LMP]1 positive) in HIV-infected patients, and could explain why EBV-driven, acquired immunodeficiency syndrome (AIDS)-related, non-Hodgkin's lymphoma occur more frequently in patients with low CD4-positive T cells.

Predominant expression of the long isoform of Bcl-x (Bcl-xL) in human lymphomas.

Bcl-x is a member of the bcl-2 family of proteins which are characterized by their ability to modulate apoptosis. Alternative splicing results in two distinct bcl-x mRNAs encoding a long isoform, bcl-xL, which acts as a bcl-2 agonist; and a short isoform, bcl-xS, which inhibits bcl-2 effects. The aim of the study was to determine whether bcl-x is expressed in lymphoma tissues and to characterize the respective production of bcl-xs and bcl-xL. We investigated the expression of bcl-x mRNA in a series of 50 non-Hodgkin's lymphomas (NHL) and Hodgkin's disease (HD) cases using a RT-PCR method in order to amplify both transcripts simultaneously, and to estimate their relative abundance. The rearrangements of the bcl-2 gene were analysed by RT-PCR expression of the hybrid bcl-2-lgH mRNA. In addition, 20 PCR-positive NHL cases and three HD cases were analysed by immunohistochemistry using bcl-x polyclonal antisera. RT-PCR showed bcl-x expression in 43/45 NHLs and 5/5 HD cases. The bcl-xL transcript was predominant in all positive cases and was associated with variable amounts of bcl-xS. There was no significant correlation between the profile of bcl-xL/bcl-xS expression and the histological and immunological subtyping. Bcl-x immunodetection was positive in the neoplastic cell component in all analysed cases, but the degree of staining was highly variable between cases. Expression of the hybrid bcl-2-IgH gene was detected by RT-PCR in five cases of follicular NHL and in one case of HD, but this group of tumours did not display a particular profile of bcl-xL/bcl-xS expression. We conclude that bcl-x is commonly expressed by malignant cells in various types of malignant lymphomas, with a predominance of the bcl-xL transcript. Since the corresponding bcl-xL isoform can block the cell death machinery and potentialize bcl-2 effects, it may be involved in some pathways of lymphomagenesis.

Frequent expression of the cell death-inducing gene Bax in Reed-Sternberg cells of Hodgkin's disease.

The expression of a cell death-inducing gene, Bax, was investigated in 52 cases of Hodgkin's disease in parallel with Epstein-Barr virus and was compared with the immunodetection of other apoptosis-regulating proteins, Mcl-1, Bcl-2, and Bcl-x. Bax immunostaining was found in 92% of the cases, among them 28% with a strong signal in more than 75% of the Reed-Sternberg cells. Mcl-1 was positive in 80% of the cases, whereas Bcl-2 and Bcl-x were found in 53% and 88% of the cases, respectively. Of 48 (89%) Bax-positive tumors, 43 were found to express apoptosis-inhibiting proteins such as Mcl-1 or Bcl-2. With the exception of 1 case, all Bax-positive tumors also expressed either Bcl-2, Bcl-x, Mcl-1, or combinations of these anti-apoptotic proteins. No correlation was found between Bax expression and the presence of apoptotic cells as detected by morphology and the in situ 3' OH-DNA end-labeling technique. Our findings show that the apoptosis-inducing gene Bax expression is frequently expressed in Hodgkin's disease, providing a potential explanation for the good chemoresponses generally obtained for patients with this neoplastic disorder.

Deletion variants within the NF-kappa B activation domain of the LMP1 oncogene prevail in acquired immunodeficiency syndrome-related large cell lymphomas and human immunodeficiency virus-negative atypical lymphoproliferations.

This sequencing study of 17 acquired immunodeficiency syndrome-related lymphomas (9 primary brain, 8 systemic) and 8 human immunodeficiency virus-negative atypical lymphoproliferations expressing large amounts of the latent membrane protein 1 (LMP1) of Epstein-Barr virus was performed to characterize the carboxy terminal NF-kappa B activation domain of LMP1 at the molecular level in an immunocompromised host. In-frame deletions within the NF-kappa B activation domain were identified in all but 2 primary brain lymphomas, 4 systemic lymphomas, and 4 atypical lymphoproliferations, ie, in 60% of cases. In addition, non silent point mutations (range 1 to 5, mean 3.3) were detected in all cases. Although all changes occurred within the first 100 nucleotides of the carboxy terminal NF-kappa B activation domain--a critical sequence for the protein half-life--not a single point mutation was found in the remaining 62 nucleotides, necessary for malignant transformation. Such a clustering of nonrandom sequence variations, associated with a high oncoprotein expression in immunocompromised hosts, suggests that this part of the LMP1 oncogene behaves as a hypervariable region with natural selection of growth-promoting variants through prolongation of the protein half-life.

Vincristine degradation by serum from leukemic patients: role of myeloperoxidase.

Myeloperoxidase (MPO) has been shown to catalyze the in vitro degradation of vincristine (VCR). Given that MPO is a lysosomal enzyme that can be released into the circulation by both normal activated and leukemic myeloid cells, we investigated the possibility that sera from patients with acute myeloblastic leukemia (AML) might exhibit an increased capacity to degrade VCR. 31 serum samples (23 from patients with acute myeloblastic leukemia and 8 from patients with other conditions) were analyzed after incubation with ((3)H)VCR by using HPLC. Sera from patients with AML demonstrated an increased ability to breakdown VCR when compared to either normal sera or to sera from patients with lymphoid leukemias. VCR degradation was significantly increased by adding hydrogen peroxide, an electron donor for MPO, to the sera and was almost completely inhibited by adding 1 mM acetaminophen, an inhibitor of MPO. VCR peroxidation in the presence of hydrogen peroxide correlated both with the number of leukemic blasts in the circulation at the time the sera were obtained and with serum MPO concentrations determined by an immunoassay. These data suggest that the inactivity of VCR in AML may be due in part to its rapid peroxidation to inactive species by the MPO of leukemic myeloblasts.

High incidence of the t(2;5)(p23;q35) translocation in anaplastic large cell lymphoma and its lack of detection in Hodgkin's disease. Comparison of cytogenetic analysis, reverse transcriptase-polymerase chain reaction, and P-80 immunostaining.

Fifty-six cases of anaplastic large cell lymphoma (ALCL), 23 cases of Hodgkin's disease, and 16 cases of diffuse large cell lymphoma were investigated for the t(2;5)(p23;q35) translocation. The translocation was detected by using cytogenetic analysis, reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry with P80 antibody directed against the kinase domain of anaplastic lymphoma kinase (ALK) of the chimeric NPM/ALK protein. In all but three cases of ALCL, we found an agreement between cytogenetic analysis, RT-PCR, and P80 staining. However, in one case, the t(2;5) translocation was detected with cytogenetic analysis, but RT-PCR and P80 staining were found to be negative. Conversely, in another case the karyotype was normal, but the hybrid mRNA and P80 staining were found to be positive. In one case, malignant cells showed a translocation involving chromosomes 1q25 and 2p23 and were strongly positive for P80 staining. Such a result could be expected because P80 antibody detects the kinase domaine of the ALK protein encoded by chromosome 2p23. Overall 73.2% (41 of 56) of cases were found to be positive. However, the highest percentage (23 of 26 cases; 88.5%) of P80 positive cases was found in children compared with 60% (18 of 30 cases) in adult ALCL (P < .05). In Hodgkin's disease, Reed-Sternberg cells were found to be clearly negative by RT-PCR and with P80 antibody. The latter results suggest that Hodgkin's disease and t(2;5)-positive ALCL are distinct biological entities and that the demonstration of the t(2;5) translocation is of diagnostic importance in differentiating these two entities. The results of the present study indicate that immunohistochemistry with P80 antibody is a reliable method for detecting NPM/ALK chimeric protein.