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.

Prevalence of HTLV-I Tax in a subset of patients with rheumatoid arthritis.

Objective: In regions of the world where the human T cell lymphotropic virus type I (HTLV-I) is endemic, it is recognized that infection with this virus is associated with autoimmune diseases such as rheumatoid arthritis (RA). Moreover, mice transgenic for the HTLV-I Tax gene develop a disease akin to RA. The observation that about 8% of healthy American blood donors carry HTLV-I Tax in their lymphocytes (1) prompted studies to determine whether Tax positivity is more prevalent among patients with RA and if so, whether its sequence is homologous with prototypic HTLV-I Tax.

The role of human T cell lymphotropic virus type I tax in the development of cutaneous T cell lymphoma.

Although it has been well established that the human T cell lymphotropic virus type I (HTLV-I) causes adult T cell leukemia/lymphoma (ATLL) in regions of the world where this virus is endemic, its role in the pathogenesis of cutaneous T cell lymphoma (CTCL) in the Western world has been less well established. Most patients with CTCL are negative for antibodies to the structural proteins of HTLV-I, and thus a causative role for this virus is usually dismissed. However, the Tax sequence of HTLV-I has been found in the peripheral blood mononuclear cells of practically all patients with CTCL.

Non-HIV retroviral associations with rheumatic disease.

While the human T-cell lymphotropic virus type I (HTLV-I) is the recognized cause of adult T cell leukemia, it is also associated with non-neoplastic, ostensibly autoimmune conditions, such as tropical spastic paraparesis. Moreover,among carriers of HTLV-I, the virus is strongly implicated in the development of a type of arthritis, which resembles rheumatoid arthritis (RA). Mice transgenic for HTLV-I tax develop RA-like pathology and Sjögren's syndrome.

Detection of the tax gene of HTLV-I in labial salivary glands from patients with Sjögren's syndrome and other diseases of the oral cavity.

Objective: To confirm a possible association between Sjögren's syndrome (SS) and the tax gene of human T lymphotropic virus type I (HTLV-I).

Methods: We studied by PCR labial salivary glands (LSG) from 50 patients with definite SS and from 58 controls including 32 patients with LSG involved by other inflammatory processes and 26 normal LSG. Antibodies to HTLV-I and antibodies to the Tax protein were searched for in serum.

Platelet production in the pulmonary capillary bed: new ultrastructural evidence for an old concept.

Although there is substantial evidence indicating that platelets are released from megakaryocytes in the capillary bed of the lung, this concept has not been universally accepted because much of the evidence has been indirect. To more definitively substantiate that platelet production takes place in the lungs, megakaryocyte and platelet production was accelerated in mice by phlebotomy or by administration of thrombopoietin, and ultrastructural analysis was performed on lung specimens. Intact megakaryocytes, megakaryocyte fragments with numerous demarcated platelet fields, dissociating intact platelets, and denuded megakaryocyte nuclei were seen in the pulmonary capillaries of mice.

Transmission of human T-cell lymphotropic virus type 1 tax to rabbits by tax-only-positive human cells.

The human T-cell lymphrotropic virus type 1 (HTLV-1) is causally related to adult T-cell leukemia and lymphoma and the neurodegenerative diseases tropical spastic paraparesis and HTLV-1-associated myelopathy. In the United States the prevalence of infection has been estimated to range from 0.016 to 0.

Absence of human T-lymphotropic virus type I tax sequences in a population of normal blood donors in the Baltimore, MD/Washington, DC, area: results from a multicenter study.

Background: It was reported recently that sequences corresponding to the human T-lymphotropic virus type I (HTLV-I) tax gene were detected in peripheral blood mononuclear cells from 8 to 11 percent of healthy blood donors without detectable antibodies to HTLV-I. A multicenter blind study was conducted to determine if these results could be independently confirmed.

Study Design And Methods: Specimens were collected from 100 anti-HTLV-I-negative healthy blood donors and from 11 anti-HTLV-I- or anti-HTLV-II-positive individuals.

The effects of Mpl-ligand, interleukin-6 and interleukin-11 on megakaryocyte and platelet alpha-granule proteins.

Thrombopoietin (Mpl ligand), interleukin-6 (IL-6), and interleukin-11 (IL-11) differ in their effects on megakaryocyte maturation and development. In the present study, the impact of these thrombocytopoietic cytokines on biochemical and structural granule and membrane components was examined. Western blotting was performed on equivalent amounts of isolated megakaryocyte or platelet protein and the relative intensities of the enhanced chemiluminescent-visualized bands were quantitated by densitometry.

Human T-cell lymphotropic virus type 1 tax among American blood donors.

In the United States, all blood used for transfusion is tested for the presence of antibodies to the structural components of the human T-cell lymphotropic viruses types 1 and 2 (HTLV-1 and -2). Based on such serologic tests, the prevalence of HTLV-1 infection is estimated to range from 0.016 to 0.

Reexamination of human T cell lymphotropic virus (HTLV-I/II) prevalence.

In the United States, blood donors are being screened for infection with human T cell lymphotropic viruses I and II (HTLV-I/II) by serologic means, which detect antibodies to the structural proteins of these viruses. Because patients with mycosis fungoides (MF) usually do not have such antibodies even though their cells harbor HTLV-I Tax and/or pol proviral sequences, it was questioned whether the prevalence of HTLV infection among healthy blood donors may also be underestimated by current means of testing. To examine this possibility, a study on specimens of relatives of mycosis fungoides patients (MFR) was begun.

Immunophenotypic identification of Sezary cells in peripheral blood.

Despite anecdotal literature that Sezary cells express the CD4+ CD7- immunophenotype, no formal validation has been published establishing the use of this immunophenotype for clinical or experimental purposes. Consequently, the only method presently available for Sezary cell identification is nuclear contour analysis, a labor-intensive procedure not generally available at most major medical centers. In this study, the accuracy of CD4+ CD7- subset quantitation for the identification of Sezary cells was examined.

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.

Determination of the true prevalence of infection with the human T-cell lymphotropic viruses (HTLV-I/II) may require a combination of biomolecular and serological analyses.

Infection with the human T-cell lymphotropic virus types I and II (HTLV-I/II) usually is determined by tests that detect antibodies to the viral structural proteins. However, recent studies revealed that patients with mycosis fungoides have proviral DNA sequences related to the HTLV transactivating-transforming gene tax, without having antibodies to the virus. These results raised the possibility that the prevalence of HTLV infection in the general population of the United States also may be underestimated.

Demonstration of antibodies to human T-cell lymphotropic virus-I tax in patients with the cutaneous T-cell lymphoma, mycosis fungoides, who are seronegative for antibodies to the structural proteins of the virus.

Although most patients with the cutaneous T-cell lymphoma, mycosis fungoides (MF), are seronegative for human T-cell lymphotropic virus-I or -II (HTLV-I/II) when tested by assays that measure only antibodies to the viral structural proteins, the majority of such patients harbor HTLV-I-related pol and tax proviral sequences that encode proteins not included in routinely used serologic tests. Tax mRNA has also been detected in their peripheral blood mononuclear cells (PBMC). Therefore, it seemed possible that these patients have antibodies to the tax protein.

Effect of thrombopoietin on the development of megakaryocytes and platelets: an ultrastructural analysis.

Megakaryocytopoiesis and platelet production can be assessed with reasonable accuracy by quantitative and functional analyses of circulating platelets. The evaluation of megakaryocytopoiesis in culture has remained unsatisfactory, particularly because platelet production is rarely observed. In mouse culture systems, megakaryocytes have been identified almost entirely by measurements of acetyl cholinesterase, size, and ploidy without concomitant assessment of maturation based on such criteria as the formation of granules, demarcation membranes, and cytoplasmic fragmentation.

Localization of human T-cell lymphotropic virus-1 tax proviral sequences in skin biopsies of patients with mycosis fungoides by in situ polymerase chain reaction.

The histopathologic diagnosis of mycosis fungoides (MF), even when clinical manifestations of the disease seem convincing, is often tenuous. The observation that practically all patients with MF harbor human T cell lymphotropic virus type I (HTLV-I) proviral sequences in their circulating lymphocytes raised the possibility that such viral footprints could be detected in their cutaneous infiltrates. Application of in situ polymerase chain reaction (PCR) to skin biopsies of 11 of 12 patients demonstrated this assumption to be correct.

Megakaryocyte and platelet structure in thrombocytopoiesis: the effect of cytokines.

This paper presents an overview of selected data which the author considers crucial to an understanding of structure/function relationships of megakaryocytes (MK) and platelets. The observation that platelet territories form within the MK cytoplasm and that, therefore, MK and platelet plasma membranes need not be structurally or antigenically identical is substantiated on the basis of results obtained with a variety of experiments. While the predominant site of MK fragmentation is still debated, it is generally accepted that such terms as "proplatelets," "giant platelets" or "megathrombocytes" refer to MK fragments consisting of more than one platelet territory.

Transcription factor NF-E2 is required for platelet formation independent of the actions of thrombopoietin/MGDF in megakaryocyte development.

Despite the importance of blood platelets in health and disease, the mechanisms regulating their formation within megakaryocytes are unknown. We generated mice lacking the hematopoietic subunit (p45) of the heterodimeric erythroid transcription factor NF-E2. Unexpectedly, NF-E2-/- mice lack circulating platelets and die of hemorrhage; their megakaryocytes show no cytoplasmic platelet formation.

Interaction of human immunodeficiency virus type 1, human T-cell leukemia/lymphoma virus type I (HTLV-I), and HTLV-II with in vitro-generated dendritic cells.

Although it is known that impairment of dendritic cells (DC) plays a role in the pathogenesis and immunosuppression of retrovirus-associated diseases, it is not clear whether, or to what extent, these antigen-presenting cells themselves become infected. The realization that the cells can be generated in vitro in larger numbers than can be isolated from circulating blood or bone marrow raised the possibility that they could be used for therapeutic purposes. Therefore, we investigated whether DC generated in vitro from CD34 precursors are susceptible to infection when cocultured with human immunodeficiency virus type 1- or human T-cell leukemia/lymphoma virus-infected cell lines.

Thrombopoietin, the Mp1 ligand, is essential for full megakaryocyte development.

The development of megakaryocytes (MKs) from their marrow precursors is one of the least understood aspects of hematopoiesis. Current models suggest that early-acting MK colony-stimulating factors, such as interleukin (IL) 3 or c-kit ligand, are required for expansion of hematopoietic progenitors into cells capable of responding to late-acting MK potentiators, including IL-6 and IL-11. Recently, the Mp1 ligand, or thrombopoietin (Tpo), has been shown to display both MK colony-stimulating factor and potentiator activities, at potencies far greater than that of other cytokines.