Persistence of human T cell lymphotropic virus type 1 (HTLV-1) sequences in peripheral blood mononuclear cells from patients with mycosis fungoides

Epstein-Barr virus in cutaneous T-cell lymphomas: evaluation of the viral presence and significance in skin and peripheral blood

The importance of viral agents in the development of cutaneous T-cell lymphomas (CTCL) is still debated. For this purpose, we retrospectively evaluated the Epstein-Barr virus (EBV) presence in Sézary syndrome (SS), mycosis fungoides (MF), inflammatory dermatoses (ID), and healthy donors (HD) using different approaches: EBV-DNA was quantified in skin biopsies and peripheral blood using real-time PCR, EBV-encoded small RNA (EBER) transcripts were detected by in situ hybridization (ISH), and latent membrane protein1-2 antigens were detected by immunohistochemistry. Skin biopsies were EBV-DNA-positive in 8/30 (27%) SS, 7/71 (10%) MF, and 2/18 (11%) ID patients and in none of the 25 normal skin samples. Positive mRNA (EBER) signals, always confined to cerebriform T lymphocytes, were found in 5/30 SS patients (17%), whereas signals in all MF and ID patients were negative. The presence of EBV-DNA in skin and blood samples was associated with a significantly lower survival in MF/SS patients. In evaluating EBV serological status, most (>70%) SS, MF, and ID patients showed a serological reactivation demonstrated by the presence of anti-EA IgG. In conclusion, although the finding of EBV-DNA in CTCL does not prove its etiopathogenetic role and may be related instead to immunosuppression, our study demonstrates that it has prognostic relevance.

Comparison of commercial and in-house Real-time PCR assays for quantification of Epstein-Barr virus (EBV) DNA in plasma

Background

Epstein-Barr virus (EBV) DNA load monitoring is known to be useful for the diagnosis and monitoring of EBV-associated diseases. The aim of this study is to compare the performance of two real-time PCR assays for EBV DNA: a commercial kit as the Q-EBV Real-Time System (Q-EBV PCR, Amplimedical, Turin, Italy) and an in-house assay (EBV RQ-PCR).

Results

The range of linearity and the degree of precision of the two assays were similar. The clinical sensitivity of Q-EBV PCR was higher for reference samples containing less than 1,000 EBV DNA copies/ml. The absolute quantitative results of the two methods were statistically correlated (R² = 0.7789; p < 0.0001), with the systematic overestimation by EBV RQ-PCR possibly linked to different amplification efficiency in calibration standards.

Conclusion

Both the commercial and the in-house assay may be appropriate for clinical use, but common standards are advisable for comparable absolute values, as these would improve the clinical utility of EBV DNA load measurement.

Mycosis fungoides in European Russia: No Antibodies to Human T Cell Leukemia Virus Type I Structural Proteins, but Virus-Like Sequences in Blood and Saliva

OBJECTIVE

Mycosis fungoides (MF) is the most frequent form of cutaneous T cell lymphoma (CTCL). Human T cell leukemia virus type 1 (HTLV-1) involvement in MF progression is a matter of debate. The goal of the investigation was to search for HTLV-1 markers in a group of MF patients from a nonendemic area to HTLV-1.

MATERIALS AND METHODS

Fifty MF patients and 60 healthy donors from Moscow and the Moscow region were examined for HTLV-1 markers by Western blot, PCR, nested PCR, PCR/Southern hybridization, TaqMan real-time PCR and sequencing.

RESULTS

Plasma samples from MF patients were repeatedly negative for antibodies to HTLV-1 structural proteins. HTLV-1 tax-related sequences (corresponding to the second exon) were found in blood from 20 of 50 MF patients and in 3 of 5 saliva specimens. Three of 8 sequenced tax-like amplimers were identical and 5 of 8 contained 1-2 substitutions. tax transcripts and antibodies to p40(tax) were detected in some 'PCR-tax'-positive MF patients. Defective HTLV-1 genomes were demonstrated in 2 of 50 MF patients. Phylogenetic analysis of the defective genome 5'-LTR sequence revealed a relationship with HTLV-1a sequences from the transcontinental subgroup of HTLV-1.

CONCLUSIONS

HTLV-1 tax-like sequences were revealed in blood and for the first time in saliva from MF patients living in an HTLV-1 nonendemic region. Expression of tax-like sequences was confirmed by both reverse transcription PCR and Western blot.

Polymorphism analysis of Epstein–Barr virus isolates of lymphoblastoid cell lines from patients with mycosis fungoides

In order to determine whether there is an association between the presence of Epstein–Barr virus (EBV) and mycosis fungoides (MF) disease progression, PCR was performed to detect the EBV status of 20 MF patients; six EBV-positive patients were found. EBV variants may differ in their biological properties, such as their ability to transform cells; therefore, the ability of these variants to immortalize B cells in vitro was analysed. Six continuously growing cell lines were obtained from prolonged cultures of unstimulated peripheral blood mononuclear cells that were taken from the six EBV-positive patients with MF. In order to characterize the EBV strains, EBNA-2 and LMP-1/LMP-2 gene polymorphisms in the six cell lines were also analysed. All patients were followed up for 10 years and it was noticed that EBV-positive patients had a poor prognosis with rapid disease progression and high mortality rates, compared to EBV-negative patients. EBV may therefore constitute a co-factor that accelerates the progression of disease.

Localization of HTLV-I tax proviral DNA in mononuclear cells

The tax sequence of HTLV-I is demonstrable in the skin and blood mononuclear cells of patients with mycosis fungoides, as well as in the mononuclear leukocytes of some healthy blood donors, but was not demonstrable when PCR/Southern analyses were carried out on preparations of high-molecular-weight genomic DNA. Therefore, it was postulated that tax DNA may not be integrated. To investigate this possibility fluorescence in situ hybridization was carried out on cells arrested in metaphase, using a probe containing the HTLV-I tax proviral DNA full-length open reading frame coding sequence. While metaphases prepared from C91PL cells, a cell line infected with HTLV-I, showed an abundance of chromosome-associated as well as extra-chromosomal signals, metaphases prepared with blood mononuclear cells from healthy tax sequence positive donors did not reveal any tax DNA associated with chromosomes. Such signals were readily detected extra-chromosomally. Although it has been demonstrated that transactivation of genes by gene products encoded by extra-chromosomal DNA may have nosocomial implications, whether transactivation by p40 tax generated from extra-chromosomal tax sequences is responsible for the development of neoplasia remains to be investigated.

Practical evaluation and management of cutaneous lymphoma

Accurate evaluation of patients with suspected or known cutaneous lymphoma requires the integration of many sources and types of information, including clinical evaluation, microscopic analysis of tissue, immunophenotyping, gene rearrangement studies, clinical staging, and longitudinal observation. Diagnoses should be based on knowledge of specific lymphoma types as described in modern classification systems. Management of patients with cutaneous lymphoma requires collaboration among dermatologists, dermatopathologists, hematopathologists, and medical, surgical and radiation oncologists. (J Am Acad Dermatol 2002;46:325-57.)

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should better understand how to evaluate and manage patients for suspected or established lymphoma of the skin. Components include the clinical history and physical examination, optimal biopsy and tissue handling, interpretation of pathology and adjunctive test results, clinicopathologic correlation, and therapy. Participants should also understand the basis for establishing a specific diagnosis of cutaneous lymphoma based on current classification and staging.

Detection of HTLV-I tax-rex and pol gene sequences of thymus gland in a large group of patients with myasthenia gravis

We report in this study the use of polymerase chain reaction (PCR) for the amplification of the genomic DNA, isolated from thymic tissue, using the primers flanking HTLV-I/II tax-rex genes and the sequence method to analyze the HTLV-I pol sequence of 27 Italian patients with myasthenia gravis. These molecular methods showed that 92.5% of patients tested positive for tax gene and 55% for pol genes; 55.5% samples were positive for both the tax gene of HTLV-I/II, and the pol gene of HTLV-I. Histologic investigation of the thymus showed that 15 samples had thymic hyperplasia, 93% tested positive for the tax gene, and 40% tested positive for both the tax and pol genes of HTLV-I. In contrast, 91.6% of thymoma-positive samples were positive for tax gene I/II and 75% positive for both genes, tax and pol type I. The sequence analysis of PCR product for tax and pol genes confirmed that these amplified products were HTLV-I, with minimal variations. Our date suggested that either HTLV-I or part of the virus genome is involved in the etiopathogenesis of myasthenia gravis.

Spontaneous interleukin-5 production in cutaneous T-cell lymphoma lines is mediated by constitutively activated Stat3

Mycosis fungoides is a low-grade cutaneous T-cell lymphoma (CTCL) of unknown etiology. In advanced stages of CTCL, a shift in cytokine profile from T(H)1 to T(H)2 is observed, which coincides with eosinophilia, high levels of immunoglobulin E, and increased susceptibility to bacterial infections. It is, however, unknown why T(H)2 cytokines predominate in advanced CTCL, and the cellular source of these cytokines also remains to be identified. In several leukemias and lymphomas, constitutively activated signal transducer and activator of transcription (Stat) signaling pathways have been detected. In a previous study, constitutive activation of Stat3 was found in tumor cells isolated from affected skin and blood from CTCL patients. Here, it is shown that CTCL tumor cell lines, but not nonmalignant cell lines, spontaneously produce interleukin-5 (IL-5), IL-6, and IL-13. Transfection of tumor cells with dominant-negative Stat3 almost completely blocks IL-5 production and strongly inhibits IL-13 production, whereas IL-6 production is unaffected. Thus, the data show that malignant CTCL cells themselves might contribute to the change in cytokine pattern accompanying progression of CTCL. In conclusion, constitutively activated Stat3 is found to mediate a spontaneous IL-5 production and regulate IL-13 production in CTCL cell lines, pointing toward a new role of Stat3 in malignant transformation.

Establishment of a seronegative human T-cell leukemia virus type 1 (HTLV-1) carrier state in rats inoculated with a syngeneic HTLV-1-immortalized T-cell line preferentially expressing Tax

Human T-cell leukemia virus type 1 (HTLV-1) causes T-cell malignancies in a small percentage of the population infected with the virus after a long carrier state. In the present study, we established a seronegative HTLV-1 carrier state in rats inoculated with a newly established HTLV-1-infected rat T cell line, FPM1. FPM1 originated from rat thymocytes cocultured with a human HTLV-1 producer, MT-2 cells, and expressed rat CD4, CD5, CD25, and HTLV-1 Tax. However, FPM1 scarcely expressed other major HTLV-1 structural proteins and failed to induce typical antibody responses against HTLV-1 in inoculated rats. In contrast, control rats inoculated with MT-2 cells generated significant levels of anti-HTLV-1 antibodies. HTLV-1 proviruses were detected in peripheral blood cells of syngeneic rats inoculated with FPM1 for more than 1 year. Analysis of the flanking region of HTLV-1 provirus integrated into host cells suggested that FPM1 cells remained in these animals over a relatively long period of time. However, a similar seronegative HTLV-1 carrier state was induced in the rats inoculated with mitomycin C-treated FPM1 cells and also in FPM1-inoculated allogeneic rats, suggesting that FPM1 could also transmit HTLV-1 into host cells in vivo. Our findings indicated that (i) HTLV-1-immortalized T cells which preferentially express HTLV-1 Tax persisted in vivo but failed to induce any diseases in immunocompetent syngeneic rats and that (ii) suboptimal levels of HTLV-1 for antibody responses allowed the establishment of persistent HTLV-1 infection.

Tumor necrosis factor-alpha and interferon-gamma, but not HTLV-I tax, are likely factors in the epidermotropism of cutaneous T-cell lymphoma via induction of interferon-inducible protein-10

We have previously shown that Interferon-Inducible Protein-10 (IP-10), a cytokine chemotactic for CD4-positive lymphocytes, is overexpressed by lesional epidermal keratinocytes and probably accounts for the epidermotropism of cutaneous T-cell lymphoma (CTCL). The tax gene of human T-lymphotropic virus-I (HTLV-I) immortalizes CD4-positive lymphocytes, induces IFN-gamma, and has been detected in patients with classical CTCL who are seronegative for HTLV-I. TNF-alpha is synergistic with IFN-gamma for the induction of IP-10. We therefore decided to define the presence of tax, IFN-gamma, TNF-alpha, and IP-10 in lesions of 19 adults with classical CTCL who were seronegative for HTLV-I. Lesional mRNAs for actin, TNF-alpha, IFN-gamma, and tax were detected by reverse-transcriptase polymerase chain reaction (RT-PCR) amplification. In addition IP-10, TNF-alpha, and IFN-gamma were detected and localized with immunocytochemistry of frozen sections. In agreement with previous observations IP-10 was overexpressed in lesional keratinocytes of all 19 patients. By RT-PCR, mRNA for IFN-gamma was detected in lesions of 8, and for TNF-alpha in lesions of 13 patients. By immunocytochemistry, TNF-alpha was expressed by lesional keratinocytes in 10 of 13 tested patients, whereas IFN-gamma was focally expressed by lesional lymphocytes and faintly by lesional keratinocytes in 9 of 13 tested patients. tax mRNA was not detected in lesions of any patient, but was easily detectable in cutaneous lesions or peripheral blood of control patients who were seropositive for HTLV-I. We conclude that TNF-alpha and IFN-gamma may cause epidermotropism by inducing IP-10. However, the tax gene of HTLV-I does not appear to be involved in the pathogenesis of classical CTCL.

Constitutive activation of a slowly migrating isoform of Stat3 in mycosis fungoides: tyrphostin AG490 inhibits Stat3 activation and growth of mycosis fungoides tumor cell lines

Mycosis fungoides (MF) is a low-grade cutaneous T cell lymphoma of unknown etiology. In this report, the Jak/Stat (Janus kinase/signal transducer and activator of transcription) signaling pathway was investigated in tumor cell lines established from skin biopsy specimens from a patient with MF. Jaks link cytokine receptors to Stats, and abnormal Jak/Stat signaling has been observed in some hemopoietic cancers. In MF tumor cells, a slowly migrating isoform of Stat3, Stat3(sm), was found to be constitutively activated, i.e., (i) Stat3(sm) was constitutively phosphorylated on tyrosine residues, and tyrosine phosphorylation was not enhanced by growth factor stimulation; (ii) band shift assays and immunoprecipitations of DNA/Stat complexes showed constitutive DNA-binding properties of Stat3(sm); and (iii) Stat3(sm) was constitutively associated with Jak3. The abnormal activation of Stat3(sm) was highly specific. Thus, neither the fast migrating isoform of Stat3 (Stat3(fm)) nor other Stats (Stat1, Stat2, and Stat4 through Stat6) were constitutively activated. The Jak kinase inhibitor, tyrphostin AG490, blocked the constitutive activation of Stat3(sm) and inhibited spontaneous as well as interleukin 2-induced growth of MF tumor cells. In conclusion, we have provided evidence for an abnormal Jak/Stat signaling and growth regulation in tumor cells obtained from affected skin of an MF patient.

Absence of Human T-Lymphotropic Virus Type I in Japanese Patients With Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphoma (CTCL) is a disease entity characterized by a primary sporadic T-cell proliferation in the skin. Human T-lymphotropic virus type 1 (HTLV-1) is a retrovirus that causes adult T-cell leukemia/lymphoma. Recently, several authors have detected the HTLV-1 genome in genomic DNA from patients with CTCL and proposed a causal relation of HTLV-1 to CTCL. However, it remains controversial because these studies contain some problems in materials used to detect HTLV-1. We investigated both fresh and cultured T lymphocytes (128 specimens) derived from 50 Japanese patients with CTCL, where HTLV-1 is endemic, by using polymerase chain reaction with four sets of primers including gag,pol,env, and pX regions of HTLV-1 to elucidate the relationship between HTLV-1 and CTCL in Japan. However, none of the 128 DNA specimens revealed positive for HTLV-1 in contrast to the previous studies. We conclude that CTCL, which does not include HTLV-1, is present although the pathogenesis of CTCL may be different by areas or races. © 1997 by The American Society of Hematology.

Absence of Human T-Lymphotropic Virus Type I in Japanese Patients With Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphoma (CTCL) is a disease entity characterized by a primary sporadic T-cell proliferation in the skin. Human T-lymphotropic virus type 1 (HTLV-1) is a retrovirus that causes adult T-cell leukemia/lymphoma. Recently, several authors have detected the HTLV-1 genome in genomic DNA from patients with CTCL and proposed a causal relation of HTLV-1 to CTCL. However, it remains controversial because these studies contain some problems in materials used to detect HTLV-1. We investigated both fresh and cultured T lymphocytes (128 specimens) derived from 50 Japanese patients with CTCL, where HTLV-1 is endemic, by using polymerase chain reaction with four sets of primers including gag,pol,env, and pX regions of HTLV-1 to elucidate the relationship between HTLV-1 and CTCL in Japan. However, none of the 128 DNA specimens revealed positive for HTLV-1 in contrast to the previous studies. We conclude that CTCL, which does not include HTLV-1, is present although the pathogenesis of CTCL may be different by areas or races. © 1997 by The American Society of Hematology.

Human T cell leukemia virus type I (HTLV-I) and human diseases

HTLV-I infection is causally associated with a variety of human diseases including leukemia/lymphoma, myelopathy, uveitis, and arthropathy. Tax protein of HTLV-I, which is considered oncogenic, binds to transcription factors or other cytoplasmic cellular molecules involved in the fundamental cell function and thereby induces cellular changes. The interaction between HTLV-I-infected cells with dysregulated function and different kinds of cells in the host, such as lymphocytes and vascular endothelial cells through viral peptides, antigen receptors cell adhesion molecules, and cytokines, appears to be one of the basic mechanisms underlying the development of HTLV-I-associated diseases. This interaction may play a major role in determining tumorigenicity and in forming clinical features of the diseases. The in vivo cell proliferation model of HTLV-I-infected cells using severe combined immunodeficient (SCID) mice can differentiate tumorigenicity from cell immortalization in vitro. The OX40 and its ligand gp34, which are induced by HTLV-I infection and directly mediate the adhesion between HTLV-I-infected T cells and vascular endothelial cells, may be critically involved in the localization and proliferation of HTLV-I-infected cells in vivo.

The difficulty of detecting HTLV-1 proviral sequences in patients with mycosis fungoides

Although most patients with cutaneous T cell lymphomas, including mycosis fungoides (MF) and its leukemic variant, the Sézary syndrome, are seronegative for antibodies to the human T cell lymphotropic viruses (HTLV-I/II), it has recently been shown that > 95% of such patients harbor proviral DNA sequences related to the region of the HTLV genome that encodes the transregulatory/transforming gene, tax. However, the demonstration of HTLV sequences, even after amplification by polymerase chain reaction (PCR), has not been universally successful, and some investigators continue to question this observation. In an effort to resolve this controversy, we have compared published methodologies that have been less successful with techniques currently used in this laboratory. Major differences were found in (a) the nature of the cells used [freshly isolated versus cultured peripheral blood mononuclear cells (PBMC)] and (b) the methods used to prepare samples for PCR (whole cell lysates versus DNA extracts). PBMC from 10 different MF patients and the healthy daughter of 1 of the patients were subjected to comparative analyses. While all of the PBMC lysates were positive, the DNA extract from only one of these individuals revealed HTLV tax sequences. Studies were also conducted comparing cell lysates and DNA extracts of cultured cells derived from tax sequence-positive PBMC from seven different MF patients. The cells from four of the seven were shown to have retained tax sequences after varying times in culture, when whole-cell lysates were used as targets for PCR amplification and Southern analysis, whereas none of the DNA extracts were positive. It appears that the use of whole-cell lysates instead of DNA extracts and the use of fresh instead of cultured cells greatly enhance the ability to detect HTLV-1 tax sequences in specimens from MF patients.

Interferon-inducible protein-10 and the pathogenesis of cutaneous T-cell lymphomas

Human interferon-g inducible protein-10 (IP-10), a small basic protein secreted by interferon (INF)-g stimulated keratinocytes, is chemotactic for normal CD4-positive lymphocytes and inhibits early normal and leukemic hemopoietic progenitor proliferation. Cutaneous T-cell lymphoma (CTCL) is an indolent CD4-positive lymphoma characterized by multiple skin relapses before visceral dissemination. We investigated the role of IP-10 in the biology of CTCL by using immunocytochemistry to define IP-10 expression in normal and CTCL skin biopsies. Using purified recombinant (r) IP-10, we generated a rabbit antiserum that recognized and neutralized rIP-10 but did not cross-react with any keratinocyte proteins or any other chemokine. Immunoperoxidase staining of normal epidermis demonstrated that IP-10 was expressed by basal but not by differentiated keratinocytes. The epidermis overlying CTCL lesions was often hyperplastic, IP-10 immunostaining was enhanced compared to normal skin, and extended to the suprabasal keratinocytes in 25 of 26 patients for a frequency of 96%; and 95% confidence interval (CI) of 80% to 100%. However, IP-10 was detectable in the dermal or epidermal lymphoid infiltrates in only three of these 26 patients (12%; 95% Cl, 2% to 39%). Skin clinically free of CTCL demonstrated normal IP-10 immunostaining. In one patient who had matching biopsies performed before and after treatment, IP-10 was initially overexpressed before treatment but was normally expressed when he achieved remission. These results suggest that IP-10 may play a role in the epidermotropism of CTCL. More work is required to determine whether IP-10 stimulates or inhibits CTCL proliferation. A better understanding of the growth controls operating in CTCL may be used to develop curative therapies for this disorder.

HTLV-I-seronegative, genome-positive adult T-cell leukemia: report of a case

An HTLV-I-seronegative case of adult T-cell leukemia (ATL) carrying the HTLV-I genome is reported. Screening serological tests were negative and Western blot analysis revealed only a faint band for HTLV-I p24. Polymerase chain reaction (PCR) disclosed the presence of HTLV-I gag, pol, env, pX, and LTR sequences in the lymph node and peripheral blood. Southern blot analysis revealed a monoclonal integration of HTLV-I in the lymph node and peripheral blood. The tumor cells expressed viral antigens after short-term culture. The clinical course was consistent with ATL in that the patient exhibited hypercalcemia and abnormal lymphocytosis as well as hepatosplenomegaly and lymphadenopathy. We recommend that PCR analysis for HTLV-I be performed even in seronegative cases when ATL is clinically suspected.

Failure to detect human T-lymphotropic virus type-I proviral DNA in cell lines and tissues from patients with cutaneous T-cell lymphoma

Previous molecular studies investigating the presence of HTLV-I proviral DNA in cell lines and tissue samples of patients with cutaneous T-cell lymphoma (CTCL) have reported a detection rate ranging from 0-92%. Despite the lack of epidemiologic data linking HTLV-I infection with CTCL, the molecular data still invite speculation regarding the precise role of HTLV-I in the pathogenesis of CTCL. To determine the detection rate of HTLV-I proviral DNA among CTCL patients referred to our medical center, we analyzed Epstein-Barr virus-transformed cell lines established from peripheral blood of seven CTCL patients and 43 tissue samples from 22 patients with different stages of disease. Genomic DNA was polymerase chain reaction-amplified with primers within the HTLV-I tax gene region. Amplification products were probed with nested oligonucleotide probes by Southern blot analysis. No HTLV-I proviral sequences were detected in the samples (0/50). Using HTLV-I/II pol primers, no HTLV-I pol gene sequences were detected. In tissues from one patient, HTLV-II pol and tax gene sequences were detected; however, HTLV-II proviral integration was not detected by Southern blot analysis of the genomic DNA. Our data suggest: (i) HTLV-I does not appear to be a primary etiologic agent in CTCL; and (ii) HTLV-II pol and tax gene sequences can be detected in a minority of CTCL patients, but this does not necessarily imply an etiologic role.

Evidence against a role for human T-cell lymphotrophic virus type I (HTLV-I) in the pathogenesis of American cutaneous T-cell lymphoma

We used a standard polymerase chain reaction (PCR)/Southern blot assay (sensitivity > 10(-5)) to detect human T-cell lymphotrophic virus type I (HTLV-I) proviral pX, pol, and env genes in the lesional skin of 42 American patients with cutaneous T-cell lymphoma (CTCL). As in some prior reports using similar methods, a variable proportion of PCR tests were positive (seven of 42 for pX, three of 42 for pol, and two of 37 for env), resulting in an overall positive test rate of 12 of 121 (10%). To determine the significance of these positive test results, we performed several additional studies. D1S80 polymorphism analysis of CTCL cases and HTLV-I PCR analysis of non-CTCL dermatosis controls showed no evidence that positive PCR tests resulted from sample mislabeling, gross HTLV-I contamination, or human endogenous retroviruses. We then modified the standard PCR assay to incorporate ultraviolet (UV) light to destroy low-level PCR contamination. With this modified assay (sensitivity > 10(-5)), only three of 12 previously positive cases were still positive, suggesting that the earlier positives were due to trace contamination of PCR reagents or trace contamination of sample DNA. This interpretation was also supported by: (i) a match between pX and pol sequences cloned from one PCR-positive specimen and the MT4-positive control, (ii) our inability to confirm HTLV-I in any PCR-positive case using genomic dot blotting (sensitivity > 10(-2)), and (iii) negative PCR results when new samples from two of the remaining positive cases were analyzed. Finally, we used our modified UV/ PCR/Southern blot assay to test an additional 28 cases of American CTCL for pX. All of them were negative. Although these studies of 70 cases of American CTCL do not exclude the possibility that another virus is involved in the pathogenesis of this disease, they provide strong evidence against a role for HTLV-I. Furthermore, they emphasize the need for special strategies to control for false-positive PCR tests that can result from even trace levels of contamination with viral DNA. As a consequence, associations between diseases and viruses should be viewed skeptically if they are based primarily on conventional PCR data.

Clinical implication of the integration patterns of human T-cell lymphotropic virus type I proviral DNA in adult T-cell leukemia/lymphoma

In this review, we discuss the possible relationship between the clinical characteristics and the integration patterns of human T-cell lymphotropic virus type I (HTLV-I) proviral DNA in patients with adult T-cell leukemia/ lymphoma (ATL). Some ATL patients show unusual integration patterns such as multiple or defective HTLV-I and have clinical characteristics unlike those of most ATL patients who have the characteristic integration pattern of one complete provirus. Multiple HTLV-I integrations can be detected as two or more bands using the standard Southern blotting method when the tumor cellular DNA is digested with an endonuclease that does not cleave within the provirus. This includes cases of one tumor cell clone carrying two or more copies of the provirus, or alternatively two or more cell clones, each carrying one copy of the provirus. The former group of patients always manifest severe dyspnea and hypoxemia with unusual organ infiltrations including the retina and muscle and an extremely aggressive clinical course. On the other hand, the latter group of patients have an indolent course with skin lesions or small T lymphocytes with cleaved or lobulated nuclei. A solitary defective HTLV-I in some ATL patients can be detected as one smaller band after digestion of cellular DNA with an endonuclease that does not cleave within the provirus. These patients generally have a favourable clinical course with small cleaved or bilobulated T lymphocytes without lymphadenopathy or skin lesions. These findings suggest that there are clinical implications for the integration patterns of HTLV-I and this may be one of the explanations for the heterogeneous behaviour of the disease. Such studies may provide information on the relationship between virus integration and the clinical manifestations and also improve our understanding of the pathogenesis of ATL.

Galectin-3, a beta-galactoside-binding animal lectin, is a marker of anaplastic large-cell lymphoma

Galectin-3 is a member of a newly named family of beta-galactoside-binding animal lectins, which has been described with a number of possible important biological functions, including the regulation of cell growth and association with tumor transformation. This protein has a wide tissue distribution but is notably not expressed by normal lymphocytes. We have previously shown that galectin-3 is markedly up-regulated in HTLV-I-infected T cells, most likely mediated by the viral transactivating protein Tax. In this study, we surveyed various lymphomas by immunohistochemistry and found the expression of galectin-3 in all of the 8 cases of Ki-1+ anaplastic large-cell lymphoma (ALCL). Immunoreactivity for galectin-3 was found in a majority of the neoplastic cells in the ALCLs studied. In contrast, only 2 of the 35 cases of other types of lymphoma, including various Hodgkin's and non-Hodgkin's lymphomas, were positive. Unlike the cases of ALCL, immunoreactivity for galectin-3 in these 3 cases was found only sporadically in a small number of neoplastic cells. Thus, galectin-3 may prove to be a useful marker for ALCL and its expression in neoplastic cells in ALCL may contribute to the biological behavior of this specific type of lymphoma.