Kaposi's sarcoma in human T-cell leukemia virus type I-associated adult T-cell leukemia

Kaposi's sarcoma (KS) developed in a patient with human T-cell leukemia virus type I (HTLV-I)-associated adult T-cell leukemia who was treated with a short-term course of monoclonal antibody immunotherapy. The presentation was transient and temporally related to the underlying clinical course. The association of KS in an HTLV-I infected, but not human immunodeficiency virus (HIV)-infected, individual should alert investigators to the occurrence of KS in retroviral-associated diseases other than acquired immunodeficiency disease syndrome. Recognition of the similarities and differences between HTLV-I and HIV infections may provide insights concerning the angiopathogenesis of KS.     

Human T-cell leukemia/lymphoma virus: the retrovirus of adult T-cell leukemia/lymphoma

Human T (thymus-derived)-cell leukemia/lymphoma virus (HTLV) is a new retrovirus first isolated from T-cell lines from a patient with cutaneous T-cell lymphoma from the southeastern United States. Closely related viruses have since been isolated from several patients with adult T-cell leukemia and lymphoma (and some normal persons) from different areas of the world. HTLV is not a genetically transmitted endogenous virus of humans, but it rather is acquired by postzygotic infection. Natural antibodies to several purified viral proteins have been observed in infected individuals. HTLV is transmissible in vitro to human cord blood T cells, and infection results in an increased growth rate, a reduced requirement for (and often independence from) T-cell growth factor, and an abrogation of the crisis period that usually occurs a month after the establishment of normal T-cell cultures. These data suggest that HTLV is the etiologic agent in some human cases of leukemia and lymphoma.     

Human T-cell lymphotropic virus I and adult T-cell leukemia: report of a cluster in North Carolina

PURPOSE: Human adult T-cell leukemia-lymphoma is a malignant, proliferative disease of CD4+ lymphocytes associated with infection with human T-cell lymphotropic virus type I (HTLV-I). Following the presentation of a patient who was infected with the virus, we undertook a study of his family members and sexual contacts to see if a cluster of infected persons could be identified. CASE REPORT: A black heterosexual North Carolina native with a history of drug abuse presented with jaundice, and pancytopenia subsequently developed. He then became hypercalcemic and leukemic, with high numbers of circulating, morphologically abnormal CD4+ lymphocytes. RESULTS: As determined by radioimmunoassay and immunoblot analyses, the serum of the index case contained antibodies against core proteins (p19 and p24) of HTLV-I. When cultured in vitro with interleukin-2, the lymphocytes expressed HTLV-I specific core proteins. The virus recovered from these T cells was transmitted to cord blood T cells, which became immortalized for continuous growth in vitro, expressed HTLV-I p19 protein, and displayed characteristic C-type particles by electron microscopy. Studies of family members and sexual contacts, all of whom were black, heterosexual central North Carolina natives, revealed five of 28 whose serum had anti-HTLV-I antibodies as determined by radioimmunoassay and immunoblot. Neither the patient nor the seropositive family/contacts had antibodies against human immunodeficiency virus proteins. Four of the six people with HTLV-I infection had no history of intravenous drug abuse. Three of the five seropositive family/contacts had circulating, morphologically abnormal lymphocytes suggestive of "preleukemic" or "smoldering" human adult T-cell leukemia-lymphoma.     

Human T-cell lymphotropic virus type I associated adult T-cell leukaemia/lymphoma in Taiwan Chinese

Twenty-five Chinese patients with human T-cell lymphotropic virus type I (HTLV-I) associated adult T-cell leukaemia/lymphoma (ATLL) were identified in Taiwan. No patients had been outside Taiwan and none were descendants of Japanese heritage. Their ages ranged from 28 to 71 years. There were 17 men and eight women. Main clinical and laboratory features at presentation were lymphadenopathy (16), skin lesions (11), hepatosplenomegaly (11), pulmonary lesions (11), hypercalcaemia (10) and bone marrow infiltration (14). Peripheral blood was characterized by leucocytosis with presence of pleomorphic abnormal lymphocytes but rare anaemia or thrombocytopenia. The clinical subtypes were acute in 15, chronic in three, smouldering in one, and lymphoma type in six. The immunophenotypes of the ATLL cells were characterized by the expression of CD2+, CD4+, CD7-, CD8- and CD25+. The overall prognosis was poor with a median survival of 5 months. The acute form had a significantly shorter survival (2 months) than lymphoma type (13 months). Susceptibility to various infections was common. Pulmonary complications accounted for 73% of the causes of death. The clinicopathologic features of ATLL in Taiwan are indistinguishable from those in HTLV-I endemic areas. The present series adds to the knowledge of the worldwide pattern of the disease.     

Two types of defective human T-lymphotropic virus type I provirus in adult T-cell leukemia

Adult T-cell leukemia (ATL), an aggressive neoplasm of mature helper T cells, is etiologically linked with human T lymphotropic virus type I (HTLV-1). After infection, HTLV-I randomly integrates its provirus into chromosomal DNA. Since ATL is the clonal proliferation of HTLV-I- infected T lymphocytes, molecular methods facilitate the detection of clonal integration of HTLV-I provirus in ATL cells. Using Southern blot analyses and long polymerase chain reaction (PCR) we examined HTLV-I provirus in 72 cases of ATL, of various clinical subtypes. Southern blot analyses revealed that ATL cells in 18 cases had only one long terminal repeat (LTR). Long PCR with LTR primers showed bands shorter than for the complete virus (7.7 kb) or no bands in ATL cells with defective virus. Thus, defective virus was evident in 40 of 72 cases (56%). Two types of defective virus were identified: the first type (type 1) defective virus retained both LTRs and lacked internal sequences, which were mainly the 5' region of provirus, such as gag and pol. Type 1 defective virus was found in 43% of all defective viruses. The second form (type 2) of defective virus had only one LTR, and 5'- LTR was preferentially deleted. This type of defective virus was more frequently detected in cases of acute and lymphoma-type ATL (21/54 cases) than in the chronic type (1/18 cases). The high frequency of this defective virus in the aggressive form of ATL suggests that it may be caused by the genetic instability of HTLV-I provirus, and cells with this defective virus are selected because they escape from immune surveillance systems.     

Development of leukemia in mice transgenic for the tax gene of human T-cell leukemia virus type I.

The human T-cell leukemia virus type I Tax protein trans-activates several cellular genes implicated in T-cell replication and activation. To investigate its leukemogenic potential, Tax was targeted to the mature T-lymphocyte compartment in transgenic mice by using the human granzyme B promoter. These mice developed large granular lymphocytic leukemia, demonstrating that expression of Tax in the lymphocyte compartment is sufficient for the development of leukemia. Furthermore, these observations suggest that human T-cell leukemia virus infection may be involved in the development of large granular lymphocytic leukemia.     

Human T lymphotropic virus type-I and adult T-cell leukemia in Japan

HTLV-I is the first retrovirus to be associated directly with human malignancy. In ATL-endemic areas, the rate of HTLV-I carriers is high. Both HTLV-I and ATL have been shown to be endemic in some regions of the world, especially in southwest Japan, the Caribbean islands, South Americas, and parts of Central Africa. Antibodies against HTLV-I have been found in over one million individuals, and more than 700 cases of ATL have been diagnosed each year in Japan alone. The cumulative incidence of ATL among HTLV-I carriers in Japan is estimated at 2.5% (3-5% in males, 1-2% in females). In endemic areas, HTLV-I Ab were found in the sera of 6 to 37 percent of healthy adults over 40 years of age. This clustering is thought to be due to the limited transmission of virus between socially isolated populations. The diagnostic criteria for HTLV-I associated ATL have been defined as follows. 1) Histologically and/or cytologically proven lymphoid malignancy with T cell antigens. 2) Abnormal T-lymphocytes present in the peripheral blood, except in the lymphoma type. 3) Serum specimens for all patients with ATL have HTLV-I Ab. 4) Demonstration of clonality of HTLV-I proviral DNA is a definite diagnosis of ATL. ATL shows diverse clinical features but can be divided into four subtypes: acute, chronic, smoldering, and lymphoma type. The pattern of HTLV-I transmission is through one of three different modes. Infected mothers can transmit the virus to newborns mainly via breast milk. The virus also can be transmitted from male to female by sexual intercourse, and through blood transfusion. Chemotherapy is not effective; the acute and lymphoma types have a poor prognosis. ATL is generally treated with curative intent using combination chemotherapy, although long-term success has been very limited. Unfortunately that advance did not translate into an improvement in the overall survival; the median remain 10 months. In contrast, smoldering ATL, or some cases of chronic ATL, may have a more protracted natural course, which may be compromised by aggressive chemotherapy. Alternative strategies for both acute and chronic forms are clearly needed. After infection of HTLV-I, there is a long latent period before onset of ATL. Analyses by PCR showed that clearly proliferation occurred in intermediate state or even carriers with high virus load. Such clonal proliferation might be preleukemic stage, which suggested that carriers with high virus load should be risk group to have ATL.     

Simian T-cell leukemia virus type I infection in captive baboons.

Human T-cell leukemia virus type (HTLV-I) is a type C retrovirus that has been linked to both adult T-cell leukemia and neurological disorders in humans. Baboons and other Old World non-human primates harbor a related virus termed simian T-cell leukemia virus type 1 (STLV-I), which may also be associated with neoplastic disease. To explore the utility of the baboon as a model for HTLV-I infection and disease, 329 baboons from a colony of 3200 at the Southwest Foundation for Biomedical Research (SFBR) were analyzed for the presence of antibodies against STLV-I. An overall seroprevalence rate of > 40% was found, with higher rates in females versus males. Furthermore, seroprevalence rates increased dramatically with age, reaching greater than 80% in animals over the age of 16. Molecular and antigenic analysis of proviral DNA isolated from both tumor tissue and a cell line isolated from a baboon with non-Hodgkin's lymphoma (NHL) indicates that STLV-I in this colony is closely related to HTLV-I. Furthermore, monoclonally integrated provirus isolated from lymphoma tissue was detected, strongly implicating STLV-I in the etiology of this malignancy. DNA primer pairs homologous to HTLV-I sequences amplified both HTLV-I and STLV-I, but not HTLV-II, providing further evidence for a close genetic relationship between baboon-derived STLV-I and HTLV-I. The detailed study of a large population of naturally infected baboons may therefore shed some light into the complex processes required for the induction of disease associated with HTLV-I infection in humans.     

Serological cross-reactivity between envelope gene products of type I and type II human T-cell leukemia virus.

People exposed to type I human T-cell leukemia virus (HTLV-I) develop antibodies to an antigen at the surface of virus-infected cells, designated human T-cell leukemia virus membrane antigen (HTLV-MA). In an earlier study, we demonstrated that the major component of HTLV-MA is gp61, a glycoprotein encoded by the HTLV env gene. In the current study, we found that human antibodies that react with HTLV-MA on cells infected with HTLV-I react equally well with HTLV-MA on C3-44/MO, a target cell infected with type II HTLV. A glycoprotein with an approximate size of 67 kDa, gp67, was identified in C3-44/MO using immunoprecipitation and NaDodSO4/PAGE analysis. The positions of serine and cysteine residues were determined in the amino terminus of gp67 by radiolabel sequencing analysis. Comparison with the amino acid sequence deduced from the primary nucleotide sequence of HTLV-IIMO virus reveals that gp67 is also encoded, at least in part, by the env gene. The gp67 of HTLV-IIMO, like the env gene product of HTLV-ICR, gp61, is recognized both by antibodies from a HTLV-IIMO-infected patient with a variant form of hairy cell leukemia, and by antibodies from patients with HTLV-I-associated adult T-cell leukemia/lymphoma. These results indicate that, despite the divergence between HTLV-I and HTLV-II, the major env gene products of the two types of HTLV are conserved to the degree that they are serologically cross-reactive.     

Serum dehydroepiandrosterone and DHEA-sulfate in patients with adult T-cell leukemia and human T-lymphotropic virus type I carriers

The serum levels of dehydroeplandrosterone (DHEA) and DHEA-sulfate (DHEA-S) were determined by radioimmunoassay in 38 patients with adult T-cell leukemia (ATL). Levels of serum DHEA and DHEA-S were also measured in 60 human T-lymphotropic virus type I (HTLV-I) carriers, and did not differ from those in 60 healthy control subjects. Serum levels in patients with ATL were lower than those in the age- and sex-matched healthy controls and in HTLV-I carriers with statistical significance. Serum DHEA and DHEA-S in male patients with acute and lymphoma-type ATL were 1.06 ± 0.77 ng/ml and 245.8 ± 192.9 ng/ml, respectively. Levels in male patients with chronic and smoldering-type ATL were 1.69 ± 0.68 ng/ml and 477.6 ± 251.5 ng/ml, respectively. Serum levels of DHEA and DHEA-S in patients with acute and lymphoma-type ATL were significantly lower than those in patients with chronic and smoldering-type ATL (P < 0.05). These data suggest that a decrease in serum levels of DHEA and DHEA-S may be associated with patients who have some clinical subtypes of ATL. Moreover, androgens may have a therapeutic role in patients with ATL, as administered in patients with hairy-cell leukemia. Because there is at present no curative chemotherapy for ATL, a trial combination of androgens and standard chemotherapy may be a reasonable therapeutic option in such patients. © 1996 Wiley-Liss, Inc.     

Human immature thymocytes as target cells of the leukemogenic activity of human T-cell leukemia virus type I

The risk of developing adult T-cell leukemia (ATL) associated with neonatal infection by human T-cell leukemia virus type I (HTLV-I) suggests that early events triggered by HTLV-I might be of crucial importance in initiating the multistep lymphoproliferative process leading several decades later to the development of leukemic disease. Thus, infection of thymocytes early in life might be directly correlated with the development of ATL. In the present study, we show that in vitro infection of mature (CD2+CD3+) or immature (CD2+CD3-) thymocytes resulted in the exogenous interleukin (IL)-2-dependent proliferation of HTLV-I-positive thymocytes, most of them displaying a CD2+CD3-CD4+ phenotype and expressing the CD25 molecule, the alpha chain of the IL-2 receptor. Furthermore, the CD80 and CD54 antigens, normally expressed by thymic stromal cells, were detected on these transformed thymocytes, indicating that HTLV-I infection may disturb the cooperation between thymocytes and their thymic environment. These HTLV-I-positive thymocytes were producing significant amounts of IL-6, which was found to be implicated in their proliferation and in the expression of CD25, as demonstrated by blocking experiments using a monoclonal antibody to IL-6. The present study suggests that immature thymocytes may provide an environment favorable to the unfolding of events leading to leukemia.