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Human T-cell leukemia virus-1 (HTLV-1) is the first pathogenic human retrovirus discovered in 1980.1 HTLV-1 causes 2 devastating diseases: adult T-cell leukemia/lymphoma (ATL) and a neurological disorder, HTLV-1–associated myelopathy/tropical spastic paraparesis (HAM/TSP or, more briefly, HAM). ATL becomes apparent in 2% to 5% of those infected with HTLV-1; another 1% to 2% will develop HAM.2 There are usually 2 to 3 decades of latency after the infection before the onset of symptoms. A second HTLV (HTLV-2) isolated in 1982 has been causally linked to HAM, but not ATL.3 In other cases, HTLV-1 and HTLV-2 infection may remain asymptomatic for years while being transmitted from person-to-person through host cells in body fluids and breast milk, blood cell transfusions, and solid organ transplantation. There are no licensed vaccines to prevent HTLV-1 or HTLV-2 infections.

The influence of human T-cell leukemia/ lymphoma virus type II (HTLV-II) in individuals also infected with HIV-1 is poorly understood, To evaluate the reciprocal influence of HTLV-II and HIV-1 infection, primary peripheral blood mononuclear cell (PBMC) cultures from coinfected individuals were established in the presence of interleukin 2 (IL-2), In these cultures, the kinetics of HTLV-II replication always preceded those of HIV-1. Noteworthy, the kinetics of HIV-1 production were inversely correlated to the HTLV-II proviral load in vi7vo and its replication ex vivo. These observations suggested a potential interaction between the 2 retroviruses, In this regard, the levels of IL-2, IL-6, and tumor necrosis factor-alpha (TNF-alpha) were measured in the same coinfected PBMC cultures. Endogenous IL-2 was not produced, whereas IL-6 and TNF-alpha were secreted at levels compatible with their known ability to up-regulate HIV-1 expression. The HIV-suppressive CC-chemokines RANTES, macrophage inflammatory protein-1 alpha (MIP-1 alpha), and MIP-1 beta were also determined in IL-2-stimulated PBMC cultures. Of interest, their kinetics and concentrations were inversely related to those of HIV-1 replication. Experiments were performed in which CD8(+) T cells or PBMCs from HTLV-II monoinfected individuals were cocultivated with CD4(+) T cells from HIV-1 monoinfected individuals separated by a semipermeable membrane in the presence or absence of antichemokine neutralizing antibodies. The results indicate that HTLV-II can interfere with the replicative potential of HIV-1 by upregulating viral suppressive CC-chemokines and, in particular, MIP-1 alpha. This study is the first report indicating that HTLV-II can influence HIV replication, at least in vitro, via up-regulation of HIV-suppressive chemokines, (Blood, 2000;95: 2760-2769) (C) 2000 by The American Society of Hematology.

An extensive collaboration of laboratories and investigators has been developed to define the seroprevalence of human T-cell leukaemia/ lymphoma virus type I and II (HTLV-I and -II) infection in Europe. An algorithm for serological screening for HTLV-I and -II infection has been established by consensus. Data from screening almost 4 million subjects, including many unpublished studies, which conform to this algorithm are presented. In extensive studies the seroprevalence of HTL.V-I/II in blood donors is low, ranging from1 in 100,000 to 30 in 100,000 donors and is due predominantly to HTLV-I. In antenatal clinics in France and the United Kingdom the seroprevalence of HTLV-I is0.2%, but surveillance in this setting has been limited and extensive study of the seroprevalence of HTLV-I/II infection in pregnant women in Europe is urgently required to determine the need for HTLV-I/II antenatal screening. HTLV-I is present in populations who have immigrated to Europe from endemic areas and is spreading into indigenous European populations, particularly through sexual transmission to females. HTLV-II infection is present predominantly amongst IVDU and is usually a coinfection with HIV-I. There are considerable regional differences in HTLV-II seroprevalence.

International audience; Langerhans cells (LC) belong to the dendritic cell family and represent the principal antigen presenting cells populating squamous epithelia. We have reported the presence of human immunodeficiency virus Type 1 (HIV-1) proviral DNA and RNA in purified LC from the epidermis of seropositive patients. The aim of this study was to quantify HIV-1 proviral DNA in LC of infected patients using a competitive polymerase chain reaction (PCR) assay. Bulk epidermal cell (EC) suspensions were obtained from the skin of nine AIDS patients and six seronegative subjects. Purified LC and LC-depleted EC were prepared by immunomagnetic separation using an anti-CD1a monoclonal antibody. LC preparations did not contain T cells, as assessed by reverse transcription PCR analysis of the T cell receptor beta-chain gene (C region). In addition, no CD14+ cells could be detected in LC fractions by immunostaining of cytospin preparations. To quantify HIV-1 DNA, a new competitive PCR system was devised using SK145/150 as primers (gag) and a competitor plasmid DNA with a modified sequence (209 instead of 142 bp). The number of HIV-1 DNA copies found in the LC of AIDS patients ranged from 107 to 3,645/10(5) LC. In contrast, LC-depleted EC from the same subjects were all negative. The results indicate that in AIDS patients the frequency of infected LC is comparable to that reported for peripheral blood CD4+ T cells.

International audience; Human Langerhans cells (LC) are bone marrow-derived, HLA-DR+, CD1a+, and CD4+ dendritic antigen-presenting cells found in stratified squamous epithelia. As other members of the dendritic leukocyte family, to which they belong, LC have been reported as targets for HIV-1 infection. The aim of the present study was to investigate whether HIV-1 RNA is expressed in epidermal LC of HIV-1-infected patients. Bulk epidermal cell (EC) suspensions were prepared from skin of nine recently deceased AIDS patients and 11 seronegative controls. Purified LC (94 +/- 4% HLA-DR+ cells with no CD3+ cells, as assessed by flow microfluorimetry analysis) and LC-depleted EC were obtained by immunomagnetic separation using an anti-CD1a monoclonal antibody. Samples were analyzed for the presence of HIV-1 RNA by reverse transcription of a spliced mRNA region of the tat gene, followed by polymerase chain reaction amplification. HIV-1-spliced RNA was detected in LC from 6 of 9 patients examined, whereas LC-depleted EC fractions from the same patients were all negative. The results indicate that epidermal LC from HIV-seropositive patients actively transcribe HIV-1 proviral DNA, further supporting the hypothesis that HIV productively infected LC could serve as a reservoir of the virus in the epidermis and as a source for the infection of T lymphocytes.