Characterization and distribution of nucleic acid sequences of a novel type C retrovirus isolated from neoplastic human T lymphocytes

Natural antibodies to the structural core protein (p24) of the human T-cell leukemia (lymphoma) retrovirus found in sera of leukemia patients in Japan

In Japan, adult T-cell leukemias and lymphomas are more common than in the United States and Europe, and in the southwest part of Japan these T-cell malignancy cases appear in clusters. Therefore, we investigated the involvement in these leukemias and lymphomas of the human T-cell leukemia virus (HTLV) that was previously isolated in one of our laboratories from cultured T cells of some patients in the United States with leukemias and lymphomas involving relatively mature T cells. High titers of antibodies capable of quantitative precipitation of (125)I-labeled p24, a well characterized core protein of HTLV, were detected in 12 of 12 patients with untreated adult T-cell leukemia (ATL). (One negative was a patient on chemotherapy.) Ten of the 12 positive samples were from an area where the disease is endemic. Strong precipitating antibodies were also detected in five of seven cases of T-cell malignant lymphoma (TML) which differs from ATL by having fewer leukemic cells in the peripheral blood. High antibody titers were also observed in one of five cases of acute monoblastic leukemia and one of eight cases of chronic myelogenous leukemia in the blast phase of the disease. Low to moderate titers of antibodies were detected in several categories of leukemia (two cases of blast-phase chronic myelogenous leukemia, two cases of acute lymphoblastic leukemia of the null-cell type, and one case of acute myelogenous leukemia). Among all categories of leukemias, except ATL and TML, more cases were negative than positive for anti-p24 activity. All of 79 sera from normal Japanese, including 39 collected from the endemic ATL area of southwest Japan, were negative for antibodies to HTLV p24. All the positive reactivities observed were highly specific to HTLV. The only competition observed in the precipitation of HTLV p24 was with HTLV or with cell lines expressing HTLV and not with various animal retroviruses or a large number of human and subhuman primate cell lines, not known to be producing HTLV. The data strongly indicate an association of HTLV with the increased incidence of ATL in parts of Japan, probably with other forms of leukemias in Japan, and, less commonly, with certain T-cell malignancies in the United States.

Natural antibodies to human retrovirus HTLV in a cluster of Japanese patients with adult T cell leukemia

Human T cell lymphoma leukemia virus (HTLV) is a human retrovirus (RNA tumor virus) that was originally isolated from a few patients with leukemias or lymphomas involving mature T lymphocytes. Here we report that the serum of Japanese patients with adult T cell leukemia, but not the serum of tested normal donors, contains high titers of antibodies to HTLV. These observations, together with data from Japan showing that adult T cell leukemia is endemic in southwest Japan, suggest that HTLV is involved in a subtype of human T cell malignancy, including Japanese adult T cell leukemia.

Significant progress in dermatologic research since 1977

Some active fields of experiment dermatology have been selected to demonstrate the interaction between basic research and clinical dermatology. The identification of the Langerhans cell, the typing of mononuclear cells, and the identification of T cell growth factors have significant implication in contact dermatitis, lymphomas, etc. The group of papovaviruses is better defined in relationship to the type of disease that they produce and its oncogenic potential. Various types of vasculitis are better understood, thanks to research in humoral immunity and complement activation. Melanogenesis and its control by peptides is progressing. New specific proteins have been identified in the connective tissues, and their role has been clarified. Identification of specific proteins of keratinocytes and study of differentiation of these cells have provided useful information and some skin disorders. The control of epidermal cell proliferation and differentiation, through membrane receptors, growth factors, and intracellular enzymes, is progressively giving clues to the understanding of genetic disorders, cancers, the effect of retinoids and phototherapy.

Primary structure analysis of the major internal protein p24 of human type C T-cell leukemia virus

A human type C retrovirus [human T-cell leukemia (lymphoma) virus; HTLV], recently isolated from young adult patients with cutaneous T-cell lymphoma or leukemia, was not detectably related to other known animal retroviruses in molecular hybridization studies, by comparison of reverse transcriptase and the major core protein p24. The p24 core protein was purified to homogeneity. The amino acid composition, the COOH-terminal amino acid, and the NH(2)-terminal amino acid sequence of the first 25 residues of this major internal structural protein were determined. These results were then compared to the known structure of the internal core protein of other retroviruses. The compositional data reveal that HTLV p24 is chemically distinct from p30-p24 of other animal retroviruses, in agreement with the earlier immunological analyses. However, HTLV p24 shares the common NH(2)-terminal proline and COOH-terminal leucine of all mammalian type C viral p30s. In addition, like bovine leukemia virus (BLV), HTLV lacks the common prolylleucylarginine tripeptide and the larger conserved region found near the NH(2) terminus of the other mammalian type C viral p30s. Alignment of the amino acid sequence of HTLV p24 with previously determined sequences of other retrovirus proteins, including BLV p24, reveals statistically significant sequence homology only to BLV. The results reported here demonstrate that HTLV p24 is related to but chemically distinct from the major core protein of other retroviruses. Similarly, previous results showed that there was no immunological crossreactivity of the p24 protein and reverse transcriptase of HTLV with other retroviruses, including BLV, and no nucleic acid sequence homology. However, the present results, combined with the common size of the p24 and reverse transcriptase, suggest that HTLV may be closer to BLV than any other known retrovirus.

Detection of the human T cell lymphoma virus p19 in cells of some patients with cutaneous T cell lymphoma and leukemia using a monoclonal antibody

A monoclonal antibody specific for the internal p19 protein of a type-C retrovirus (HTLV) isolated from human neoplastic T cells has been developed. Its specificity has been shown by radioimmune precipitation and by affinity chromatography of iodinated HTLV proteins. By indirect immune fluorescence this antibody recognizes only HTLV-producing cells. Examination of cells from patients with cutaneous T cell lymphomas and leukemias and with other types of lymphomas and leukemias indicated that HTLV p19 expression is rare. The monoclonal antibody will be useful in determining the natural reservoir of HTLV, possibly in a subset of mature T cell neoplasias.

Adult T-cell leukemia: antigen in an ATL cell line and detection of antibodies to the antigen in human sera

Indirect immunofluorescence of certain human sera demonstrated an antigen(s) in the cytoplasm of 1--5% of the cells of a T-cell line, MT-1, from a patient with adult T-cell leukemia (ATL), which is endemic in southwestern Japan. The antigen was not detected in other human lymphoid cell lines, including six T-cell lines, seven B-cell lines, and four non-T non-B cell lines. The antigen did not show cross antigenicity with that of herpesviruses, including Epstein--Barr virus, herpes simplex virus, cytomegalovirus, varicella-zoster virus, herpesvirus saimiri, and Marek disease virus. The proportion of antigen-bearing cells was increased by a factor of approximately 5 on culture in the presence of 5-iodo-2'-deoxyuridine. Antibodies against the antigen in MT-1 cells were found in all 44 patients with ATL examined and in 32 of 40 patients with malignant T-cell lymphomas (most of them had diseases similar to ATL except that leukemic cells were not found in the peripheral blood). The antibodies were also detected in 26% of the healthy adults examined from ATL-endemic areas but in only a few of those examined from ATL-non-endemic areas. On electron microscopy, extracellular type C virus particles were detected in pelleted MT-1 cells cultured in the presence of 5-iodo-2'-deoxyuridine.

Natural antibodies to the human T cell lymphoma virus in patients with cutaneous T cell lymphomas

Sera from patients with cutaneous T cell lymphoma and leukemia were screened for the presence of natural antibody to the human T cell lymphoma (leukemia) virus, HTLVCR, using a solid-phase radioimmunoassay. Sera from two patients, including patient CR, from whose cultured T lymphoblastic cell line (HUT102), the retrovirus HTLVCR was isolated, reacted specifically with proteins of HTLVCR. Serum from patient CR also reacted specifically with proteins of HTLVMB, an independent but highly related retroviral isolate from a patient with Sezary T cell leukemia. The specificity for HTLVCR proteins was demonstrated by solid-phase immunocompetition assays and competition radioimmunoprecipitation assays. Analysis of radioimmunoprecipitates indicated that the natural antibodies were directed against HTLVCR core proteins with molecular weights of 24,000 and 19,000 (p24 and p19). Whereas the serum reactivities for HTLVCR proteins were shown to be highly specific, additional reactivities seen against proteins of animal retroviruses including GaLV, SSV, FeLV, and BaEV were clearly shown not to be viral specific but rather were due to reactivity with cellular antigens contaminating the viral preparations or with related antigens present in fetal calf serum. These results demonstrating natural antibodies to HTLVCR provide the first evidence for a specific antibody response to a retrovirus in humans.

Immunological properties of a type C retrovirus isolated from cultured human T-lymphoma cells and comparison to other mammalian retroviruses

HTLV strain CR (HTLVCR) is a retrovirus which was isolated from a human T-cell lymphoma cell line. A protein of molecular weight 24,000 p24, was purified from this virus. Several results indicate that this p24 is an internal core protein of HTLVCR. (i) The p24 copurified with viral cores. (ii) It was labeled with 125I after disruption of the virus, but not when undisrupted virus was iodinated. (iii) The amount of p24 was directly proportional to the amount of HTLVCR. (iv) In chromatographic properties, the HTLVCR p24 behaved similarly to the major structural protein (24,000- to 30,000-molecular-weight protein) of other retroviruses. A rabbit antiserum raised against disrupted HTLVCR precipitated the labeled p24, and the precipitation was competed for by unlabeled HTLVCR and by cytoplasmic proteins from cells producing HTLVCR, but not by proteins from normal human cells, including normal growing human T-cells, and several cultured human cutaneous T-cell lymphoma lines. Proteins from several mammalian type B, type C, and type D viruses also failed to compete in this precipitation. Moreover, HTLVCR did not react in homologous and interspecies assays for p30 antigens of several mammalian type C and type D viruses. These observations agree with immunological comparisons between reverse transcriptase of HTLVCR and other retroviruses and nucleic acid sequence homology studies which indicate that the various HTLVCR isolates represent new retroviruses found in some human T-cell neoplasias.

Regulation of human T-cell proliferation: T-cell growth factor and isolation of a new class of type-C retroviruses from human T-cells

The discovery, characterization, and purification of human T-cell growth factor (TCGF) has led to the establishment of continuously growing T-lymphoblast cell lines from normal people and from patients with certain T-cell neoplasias. In contrast to normal T-cells, neoplastic mature T-cells respond directly to TCGF, requiring no prior lectin or antigen in vitro activation. The transformed T-cell lines have phenotypic characteristics consistent with the neoplastic cells of their disease of origin. A novel retrovirus, human T-cell lymphoma-leukemia virus (HTLV), has been isolated from the fresh and cultured cells of two of these patients. Subsequent characterization of this virus has shown that it is not significantly related to any known animal retrovirus, is not an endogenous (genetically transmitted) virus of man, and so far has been associated only with fresh or cultured T-cells from patients with T-cell neoplasia. These results suggest that HTLV infected some mature T-cells of some people and that it might be involved in some neoplasias involving these cells.