HTLV-I carriers among migrants from an ATL-endemic area to ATL non-endemic metropolitan areas in Japan

Increase in incidence of adult T-cell leukemia/lymphoma in non-endemic areas of Japan and the United States

Adult T-cell leukemia/lymphoma (ATLL) is a peripheral T cell neoplasm that is associated with infection by the human T-cell leukemia virus type I (HTLV-1). Although the high incidence of ATLL in HTLV-1-endemic areas is well known, population-based evidence concerning the incidence of ATLL in non-endemic areas is scarce. To answer this, we estimated the age-standardized incidence of ATLL from 1993 to 2006 for Japan and 1993 to 2008 for the US and assessed its trend using data from a population-based cancer registry in Japan and Surveillance Epidemiology and End Results (SEER) in the US. The Japanese data were collected from 15 prefectures. A total of 2055 patients in the three prefectures in Kyushu and 1380 patients in the 12 prefectures in Honshu were diagnosed with ATLL in the study period. In the US, a total of 140 patients were diagnosed with ATLL. The results showed that the age-standardized incidence in non-endemic areas in Japan and in the US significantly increased during this period (annual percent change [95%CI]; Japan-Honshu: +4.6% [1.1, 8.2]; US: +6.2% [1.5, 11.1]), while in the endemic areas of Japan there was no change (annual percent change [95%CI]; Japan-Kyushu: 0.0% [-1.6, 1.7]). This result indicates that the disease has been spread by carriers to non-endemic areas, and suggests the necessity of establishing a standard preventive strategy.

[Combined infection with HTLV-1 and Strongyloides stercoralis]

Infection of carriers of strongyloides by the human oncogenic retrovirus HTLV-1 significantly augments the number of larval parasites in the stools and impairs the action of anti-helminthic agents, resulting in an increase in immediate and longer term failure of therapy. The proliferation of cytokine type 1 secreting lymphocytes, the preferred target for viral infection, shifts the Th1/Th2 balance in favour of a Th1 response with a consequent increase in the production of gamma interferon (INF-γ). In addition to other effects, this causes a decrease in the secretion of cytokines IL-4, IL-5 and IL-13, which results in substantial reduction in total and specific IgE; failure of activation of eosinophils or stagnation in or reduction of their numbers; and an increased risk of development of a severe form of strongyloidiasis. This risk is clearly correlated with the level of anti-HTLV-1 antibodies and the amplitude of the proviral load of peripheral lymphocytes. The polyclonal expansion of infected CD4 cells might be partly due to the activation of the IL-2/IL-2R system by parasite antigens together with the action of the virus type 1 Tax protein. The fact that adult T cell leukaemia arises significantly earlier and more often in individuals with combined infection is an argument in favour of the parasite's role as a leukaemogenic co-factor. In practice it is, therefore, appropriate to initiate all available measures to eliminate parasites from co-infected hosts although this does present difficulties, and one should not reject the possibility of a diagnosis of strongyloidiasis in the absence of hypereosinophilia. In all cases of chronic strongyloidiasis without hypereosinophilia, co-infection with HTLV-1 should be looked for routinely. The same applies to carriers of strongyloides with repeated treatment failures. Finally, corticosteroids and immunosuppressants should be used only with care in HTLV-1-positive patients who seem not to be co-infected, even if they have received precautionary therapy.

Inclusion body myositis associated with human T-lymphotropic virus-type I infection: eleven patients from an endemic area in Japan

The objective of this study was to investigate the association of human T-lymphotropic virus-type I (HTLV-I) infection with sporadic inclusion body myositis in 11 patients from an endemic area in Japan. The clinical features were consistent with sporadic inclusion body myositis, and anti-HTLV-I antibodies were present in the sera of all patients. Their muscle biopsies showed the diagnostic features of inclusion body myositis, including endomysial T-cell infiltration, rimmed vacuoles, deposits of phosphorylated tau, and abnormal filaments in the nuclei and cytoplasm of the myofibers. The fibers expressed major histocompatibility complex class I antigens and were invaded by CD8 and CD4 cells. In a single human leukocyte antigen-A2-positive patient, in situ human leukocyte antigen-A*0201 / Tax11-19-pentamer staining showed pentamer-positive cells surrounding the muscle fibers. Double-immunogold silver staining and polymerase chain reaction in situ hybridization revealed that HTLV-I proviral DNA was localized on helper-inducer T cells, but not on muscle fibers. Human T-lymphotropic virus-type I proviral loads in peripheral blood mononuclear cells from each patient were similar to those in HTLV-I-associated myelopathy/tropical spastic paraparesis. This study suggests that HTLV-I infection may be one of the causes of sporadic inclusion body myositis, as has been reported in human immunodeficiency virus type-1 infection.

A major susceptibility locus for HTLV-1 infection in childhood maps to chromosome 6q27

Human T-cell leukemia/lymphoma virus type 1 (HTLV-1) is a human oncoretrovirus causing adult T-cell leukemia/lymphoma and chronic neuromyelopathy. We previously showed by segregation analysis that a dominant gene controls HTLV-1 infection through breast-feeding in children of African origin. Here, we report the mapping of this locus by a genome-wide linkage analysis based on the genetic model provided by segregation analysis. Five pedigrees of African origin with HTLV-1 seropositive children were included in the study. Significant evidence for linkage (LOD score of 3.36, P=0.00004) was obtained for chomosomal region 6q27 when using the robust analysis including only HTLV-1-infected subjects. When HTLV-1 seronegative children born to infected mothers were added in the analysis, a maximum LOD score of 2.79 (P=0.0002) was obtained for chomosome 2p25. This result was mostly due to the largest pedigree of our sample, which alone gave a LOD score of 2.90 (P=0.00013). We further excluded the role of exonic variants of two candidate genes located in the linked regions, CCR6 (chemokine receptor 6) in 6q27 and ID2 (inhibitor of DNA binding 2) in 2p25. Our results, mapping a major susceptibility locus to chromosome 6q27 and suggesting genetic heterogeneity with another locus at 2p25, pave the way to the determination of the molecular basis of predisposition to HTLV-1 infection in children.

Green tea polyphenols induce apoptosis in vitro in peripheral blood T lymphocytes of adult T-cell leukemia patients

Green tea polyphenols (TEA) are known to exhibit antioxidative activity as well as tumor-suppressing activity. In order to examine the tumor-suppressing activity of TEA against adult T-cell leukemia (ATL), we cultivated peripheral blood T lymphocytes of ATL patients (ATL PBLs), an HTLV-I-infected T-cell line (KODV) and healthy controls (normal PBLs) for 3 days in the presence of TEA and its main constituent, epigallocatechin-3-gallate (EGCg), to measure cell proliferation and apoptosis, and to quantitate mRNAs of HTLV-I pX and beta-actin genes of the cultured cells. Growth of ATL PBLs was significantly inhibited by 9-27 microg/ml of TEA and EGCg, in contrast to minimal growth inhibition of T cells of normal PBLs. Inhibition of KODV was intermediate between ATL PBLs and normal PBLs. The ATL PBLs and KODV treated with 27 microg/ml of either TEA or EGCg induced apoptotic DNA fragmentation, producing terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL)-positive cells, while the normal PBLs treated with the same concentration of TEA or EGCg produced a negligibly small number of TUNEL-positive cells, in which apoptotic DNA fragmentation was not detectable. Expression of HTLV-I pX mRNA was suppressed more than 90% in ATL PBLs by treatment with 3-27 microg/ml of either TEA or EGCg, while expression of beta-actin mRNA was much less suppressed by treatment with the same concentration of TEA or EGCg. These results indicate that TEA and EGCg inhibit growth of ATL PBLs, as well as HTLV-I-infected T-cells, by suppressing HTLV-I pX gene expression and inducing apoptotic cell death.

Human retroviruses

It was only in 1980 that the first human retrovirus, HTLV-1, was isolated. Since then, HTLV-2, HIV-1 and HIV-2 have been identified. All four viruses are transmitted with varying efficiency sexually, vertically from mother to infant, and through blood by transfusion or contamination. HTLV-1 is endemic in populations in south-west Japan, Taiwan, sub-Saharan Africa, the Caribbean, southern USA, central and south America, Australia, Papua New Guinea, Solomon Islands and western Asia. There is now epidemic spread amongst IVDUs in north and south America and southern Europe. HTLV-1 is the aetiological agent of adult T-cell leukaemia/lymphoma (ATL) and tropical spastic paraparesis/HTLV-1 associated myelopathy (TSP/HAM). Other associations which may be causative are with polymyositis, infective dermatitis, gastrointestinal malignant lymphoma and chronic lymphatic leukaemia. ATL appears to be due to malignant transformation of HTLV-1 infected cells, and TSP/HAM to chronic activation of these cells. The epidemiology of HTLV-2 is being separated only recently from HTLV-1 through the application of PCR. It has a low level of endemicity in populations of central Africa, and central and south America. It is being spread epidemically amongst IVDUs in north America and southern Europe. Its association with any pathology in man remains uncertain. HIV-1 is epidemic and spreading rapidly throughout the world. In areas where homosexual contact was the predominant mode of transmission, heterosexual spread is becoming increasingly important. The areas where heterosexual contact is the predominant mode of transmission include the worst affected populations in the world, for example sub-Saharan Africa and some of the Caribbean. There have been recent and explosive increases of HIV-1 seroprevalence in IVDUs and female prostitutes in Asia, especially Thailand and India. Of the diverse pathology following infection, only the haematological consequences are reviewed in detail: these include anaemia, leucopenia, thrombocytopenia, disorders of coagulation and lymphomas. HIV-2, compared to HIV-1, is less infectious and causes less immunosuppression with more slowly progressive disease. It is prevalent in west Africa, but is spreading, albeit slowly, far beyond.

The epidemiology of HTLV-I infection

It has been 10 years since the discovery of the human T-cell lymphotropic virus type I (HTLV-I), the first human retrovirus. During the past decade, significant progress has been made in understanding the transmission of the virus and defining its geographic distribution. It has been shown conclusively that HTLV-I is a causal factor in the induction of both adult T-cell leukemia/lymphoma and HTLV-I-associated myelopathy. However, the pathogenesis of each of these conditions is not clear, and in the light of the evidence of immune dysfunction seen among carriers of the infection, it is likely that other associated diseases will be identified. The challenge in the next decade will be to develop and implement therapeutic interventions among carriers to prevent such diseases as well as to curtail transmission within endemic populations.

Viruses and cancer. Causal associations

This review first considered some general problems in establishing causal links between a virus and a human cancer and offered some guidelines in the pursuit of this objective. Second, it reviewed the current causal associations for several candidate oncogenic viruses in relation to the tumors with which they are associated. These include Epstein-Barr virus in relation to Burkitt's lymphoma, nasopharyngeal carcinoma, Hodgkin's disease, and non-Hodgkin's lymphoma; hepatitis B and C viruses in relation to hepatocellular carcinoma; human T-cell leukemia/lymphoma virus type 1 and atypical leukemia/lymphoma; and human papilloma viruses in relation to cervical carcinoma. For some, the causal relationship is strong: hepatitis B virus with hepatocellular carcinoma, and human T-cell leukemia/lymphoma virus with adult T-cell leukemia/lymphoma. For one, the causal relationship is moderate: Epstein-Barr virus with African Burkitt's lymphoma. For others it is incomplete or inconclusive: Epstein-Barr virus with Hodgkin's disease and non-Hodgkin's lymphoma, and hepatitis C virus with hepatocellular carcinoma. Current techniques do not permit an answer for some: human papilloma virus with cervical carcinoma.

The 4th nation-wide study of adult T-cell leukemia/lymphoma (ATL) in Japan: estimates of risk of ATL and its geographical and clinical features. The T- and B-cell Malignancy Study Group

To estimate the annual incidence of adult T-cell leukemia/lymphoma (ATL) by district in Japan, a large-scale nationwide survey of ATL and of non-Hodgkin's lymphoma was performed in 1988. Questionnaires for the registration of ATL and of T-cell and non-T-cell lymphoma were distributed to the physicians in charge of this survey in 1,287 hospitals with 200 or more beds throughout Japan. From the positive rate of anti-HTLV-I antibody in adults, the annual incidence of ATL was estimated at 697, independently of the present survey. In fact, 657 cases (47% of the estimated number), newly diagnosed during the 2 years January 1986 to December 1987, were registered from 191 general hospitals throughout Japan. Major results obtained from the present survey are as follows: (1) among all ATL cases registered, 51% were from Kyushu and 29% were from metropolitan areas (Kanto, Chubu and Kinki) and most, but not all, patients with ATL in the metropolitan areas had come from the ATL-endemic areas and settled in the metropolitan areas; (2) the estimated annual incidence rates of ATL per million adults were 40.4 in males and 26.4 in females in Kyushu, the overall risk of ATL being 1.5 times as high in males as in females; (3) the age-specific incidence rate in Kyushu increased steeply with age until the age of 70, and then decreased markedly in both sexes; (4) the ratio of T-cell versus non-T-cell lymphomas was 2.9 in Kyushu but 0.5 in other districts of Japan, however, this difference regressed to the average for the whole of Japan if ATL cases were excluded; (5) 26.5% of patients with ATL had a family history of cancer, and among these, 14 (8.2%) were ATL, 21 (12.2%) were lymphoma and 17 (9.9%) were hematopoietic malignancies, the incidence of which was markedly higher than in the general population; (6) with regard to clinicopathological features of ATL, there were more advanced cases in south Kyushu than in other districts, however, these differences were not statistically significant. To clarify the chronological changes and geographical variations in the annual incidence of ATL in Japan, continuous systematic nationwide surveillance is necessary and further nation-wide studies are being prepared.

Malignant lymphomas in Japan: epidemiological analysis of adult T-cell leukemia/lymphoma (ATL)

The incidence of malignant lymphomas in Japan is relatively low compared to that in western European countries and the United States. However, in limited areas in Japan a specific type of lymphoid malignancy called adult T-cell leukemia/lymphoma (ATL), which is caused by human T-cell leukemia virus type I (HTLV-I), is highly prevalent, and there are also many healthy carriers of HTLV-I in the same areas. A cross-sectional seroepidemiological study of HTLV-I showed that the age-specific proportion of healthy HTLV-I carriers in these ATL-endemic areas increased with age, especially over 40, and was higher in females than in males. Three main routes of HTLV-I transmission are recognized: 1) vertical transmission from mother to child mainly through breast milk; 2) horizontal transmission from man to woman through semen, and; 3) parenteral transmission from carrier donor to non-carrier recipient. The annual incidence rate of ATL among HTLV-I carriers is estimated at 2.0 in males and 0.5 in females, and the cumulative risk for ATL in HTLV-I carriers during a 70-year life span is 1%-5%. Possible risk factors for ATL in addition to HTLV-I infection were considered, i.e. genetic factors, environmental factors, nutritional condition, thymus involution etc., but none of these were found to be clearly associated with ATL. To determine whether there exist particularly susceptible hosts for ATL in the ATL endemic areas, HLA types were examined, but no conclusive results on the positive relationships between HLA types and ATL manifestation or HTLV-I infection were obtained. From follow-up studies on the age-specific distribution of HTLV-I carriers in Japan, it is now speculated that the HTLV-I infection rate might have decreased naturally in the more recent generational cohort groups, even in the ATL-endemic areas. However, ATL in Japan is an important subject for study in the field of cancer epidemiology, and several trial intervention programs for the prevention of ATL, such as controls of vertical transmission from mother to child through breast milk, are now ongoing in the ATL-endemic areas of Japan.

The third nation-wide study on adult T-cell leukemia/lymphoma (ATL) in Japan: characteristic patterns of HLA antigen and HTLV-I infection in ATL patients and their relatives. The T- and B-cell Malignancy Study Group

To clarify the intrinsic factors involved in the manifestation of adult T-cell leukemia/lymphoma (ATL) in Japan, a third nation-wide study on ATL was conducted by the T- and B-cell Malignancy Study Group. General clinico-epidemiological findings on ATL and infectious modes of transmission of human T-lymphotropic virus type I (HTLV-I) from 181 ATL patients and their relatives were analyzed and the frequency of HLA antigens in 64 ATL patients was compared with that of 48 relatives of ATL probands, 340 controls from all Japan and 236 controls from Kyushu (Tanaka et al., 1984). General findings on ATL were mostly the same as those in the 2 previous nation-wide studies. The age-specific positivity rate of anti-HTLV-I antibody in siblings of ATL patients was markedly higher than that in children of ATL patients. This suggests that there is a high risk of mothers of ATL patients transmitting HTLV-I to their children who may develop clinical ATL after reaching ATL risk age. Frequencies of HLA antigens A26 and B39, among patients with ATL in ATL-endemic areas (Kyushu and South Shikoku), were higher (RR greater than 2.0 and p less than 0.05) than those of controls in Kyushu, and lower (RR less than 0.5 and p less than 0.05) with respect to A24, Bw46, Bw52, Bw61 and DR7. The frequency of Bw52 was also lower in relatives positive for anti-HTLV-I antibody than in relatives without antibody. However, these differences were not statistically significant after correction for the 45 antigens typed. These results can neither support nor refute the possibility of genetic susceptibility to HTLV-I infection and manifestation of ATL.

Epidemiological features of HTLV-I carriers and incidence of ATL in an ATL-endemic island: a report of the community-based co-operative study in Tsushima, Japan

To extend the epidemiological study on adult T-cell leukemia-lymphoma (ATL) in Japan, the geographical and demographic characteristics of carriers of human T-lymphotropic virus type I (HTLV-I) and patients with ATL were analyzed in Tsushima Island, which is one of the typical endemic areas of ATL in Kyushu, Japan. Even on the small island of Tsushima (710 km2; pop. 48,875; 123 villages), the positive rates of anti-HTLV-I antibody among the 58 villages studied varied from 2% to 50%, a fact that is probably associated with the historical events affecting the movement of the indigenous population of Tsushima Island. The positive rate of anti-HTLV-I antibody in males increased little with age; however, the female rate increased distinctly with age in moderate and high HTLV-I-endemic villages where more than 15% of the inhabitants had positive anti-HTLV-I antibody. Analysis of anti-HTLV-I antibody positivity between spouses confirmed that HTLV-I was more contagious from husband to wife than from wife to husband, which corresponded to the fact that the positive rate of anti-HTLV-I antibody in females older than 30 years was higher than that in males. Recently the rate of carrier children from HTLV-I carrier mothers was estimated at around 20%. The recent annual incidence rates of ATL among 1,000 HTLV-I carriers older than 40 years living in Tsushima Island was estimated at 2.2 in males, 0.8 in females.

Malignant lymphoma in Nebraska and Guangzhou, China: a comparative study

Two hundred thirty-four consecutive cases of malignant lymphoma (192 non-Hodgkin's lymphomas and 42 Hodgkin's disease) from Guangzhou, China, and 589 cases (498 non-Hodgkin's lymphomas and 91 Hodgkin's disease) from the University of Nebraska Lymphoma Registry were examined in a retrospective histopathologic analysis and the results compared to those of the National Cancer Institute (NCI) Working Formulation Summary. Aggressive non-Hodgkin's lymphoma was excessive in Guangzhou (82.3 per cent; P less than 0.001) and Nebraska (80.3 per cent; P less than 0.001) when compared with the NCI data (54.2 per cent). The small noncleaved cell, lymphoblastic, and diffuse mixed-cell subtypes were more frequent in China (15.6 per cent each; P less than 0.001), whereas the small lymphocytic, follicular large cell, and immunoblastic subtypes predominated in Nebraska (8 per cent, 8.4 per cent, and 21.8 per cent, respectively; P less than 0.001). The overall median age of onset for non-Hodgkin's lymphoma was 42.0 years in Guangzhou and 63.5 years in Nebraska. Hodgkin's disease represented 18 per cent of the malignant lymphomas in Guangzhou and 15 per cent in Nebraska. The mixed-cellularity type was most common in Guangzhou (52 per cent; P less than 0.001) and the nodular-sclerosing type in Nebraska (56 per cent; P less than 0.010). The low median age and excess of certain aggressive subtypes of non-Hodgkin's disease in Guangzhou suggest a possible viral etiology, whereas the excess of certain subtypes of non-Hodgkin's lymphoma in Nebraska may be related to intense agricultural activity.