Yoichiro Kusunoki

Aggressive natural killer cell leukaemia/lymphoma: report of four cases and review of the literature POSSIBLE EXISTENCE OF A NEW CLINICAL ENTITY ORIGINATING FROM THE THIRD LINEAGE OF LYMPHOID CELLS

The morphologic, immunologic, genotypic and functional properties of peripheral blood and bone marrow cells or cultured cells from four patients with a clinically aggressive non‐T, non‐B natural killer cell leukaemia/lymphoma (ANKL/L) are described. The leukaemic cells possessed medium to large granules in the cytoplasm, antigens against CD38, CD2, OKIa1 and NKH‐1 (CD56) monoclonal antibodies on their cell‐surface, and also showed natural killer (NK) activity. In addition, these ANKL/L belonged to neither T‐ nor B‐cell lineage, proved by studying clonal gene rearrangement for the Tβ, Tγ and Tδ receptors, and immunoglobulin.

Radiation dose-dependent increases in inflammatory response markers in A-bomb survivors

Purpose : The well-documented increases in malignant tumours in the A-bomb survivors have recently been supplemented by reports that non-cancer diseases, including cardiovascular disease, may also have increased in incidence with increasing radiation dose. Given that low-level inflammatory responses are widely accepted as a significant risk factor for such diseases, we undertook a detailed investigation of the long-term effects of ionizing radiation on the levels of the inflammatory markers C-reactive protein (CRP) and interleukin 6 (IL-6) in A-bomb survivors. Materials and methods : Blood samples were taken from 453 participants in a long-term epidemiological cohort of A-bomb survivors. Plasma levels of CRP and IL-6 were measured using standard antibody-mediated procedures. Relationships between CRP or IL-6 levels and radiation dose were then investigated by multivariate regression analysis. Blood lymphocytes from each individual were used for immunophenotyping by flow cytometry with murine monoclonal antibodies to CD3, CD4 and CD8. Results : CRP levels were significantly increased by about 31% Gy −1 of estimated A-bomb radiation (p =0.0001). Higher CRP levels also correlated with age, male gender, body mass index and a history of myocardial infarction. After adjustments for these factors, CRP levels still appeared to have increased significantly with increasing radiation dose (about 28% increase at 1Gy, p =0.0002). IL-6 levels also appeared to have increased with radiation dose by 9.3% at 1Gy (p =0.0003) and after multiple adjustments by 9.8% at 1Gy (p =0.0007). The elevated CRP and IL-6 levels were associated with decreases in the percentages of CD4 + helper T-cells in peripheral blood lymphocyte populations. Conclusions : Our results appear to indicate that exposure to A-bomb radiation has caused significant increases in inflammatory activity that are still demonstrable in the blood of A-bomb survivors and which may lead to increased risks of cardiovascular disease and other non-cancer diseases.

Caspase-2 and caspase-7 are involved in cytolethal distending toxin-induced apoptosis in Jurkat and MOLT-4 T-cell lines

ABSTRACT Cytolethal distending toxin (CDT) from Actinobacillus actinomycetemcomitans is a G2/M cell-cycle-specific growth-inhibitory toxin that leads to target cell distension followed by cell death. To determine the mechanisms by which A. actinomycetemcomitans CDT acts as an immunosuppressive factor, we examined the effects of highly purified CDT holotoxin on human T lymphocytes. Purified CDT was cytolethal toward normal peripheral T lymphocytes that were activated by in vitro stimulation with phytohemagglutinin. In addition, purified CDT showed cytolethal activity against Jurkat and MOLT-4 cells, which are known to be sensitive and resistant, respectively, to Fas-mediated apoptosis. Death in these cell lines was accompanied by the biochemical features of apoptosis, including membrane conformational changes, intranucleosomal DNA cleavage, and an increase in caspase activity in the cells. Pretreatment of Jurkat cells with the general caspase inhibitor z-VAD-fmk mostly suppressed CDT-induced apoptosis. Furthermore, specific inhibitors of caspase-2 and -7 showed significant inhibitory effects on CDT-induced apoptosis in Jurkat cells, and these inhibitory effects were fully associated with reduced activity of caspase-2 or -7 in the CDT-treated Jurkat cells. These results strongly suggest that CDT possesses the ability to induce human T-cell apoptosis through activation of caspase-2 and -7.

Decreases in percentages of naïve CD4 and CD8 T cells and increases in percentages of memory CD8 T-cell subsets in the peripheral blood lymphocyte populations of A-bomb survivors

Abstract Yamaoka, M., Kusunoki, Y., Kasagi, F., Hayashi, T., Nakachi, K. and Kyoizumi, S. Decreases in Percentages of Naïve CD4 and CD8 T Cells and Increases in Percentages of Memory CD8 T-Cell Subsets in the Peripheral Blood Lymphocyte Populations of A-Bomb Survivors. Radiat. Res. 161, 290–298 (2004). Our previous studies have revealed a clear dose-dependent decrease in the percentage of naïve CD4 T cells that are phenotypically CD45RA+in PBL among A-bomb survivors. However, whether there is a similar radiation effect on CD8 T cells has remained undetermined because of the unreliability of CD45 isoforms as markers of naïve and memory subsets among the CD8 T-cell population. In the present study, we used double labeling with CD45RO and CD62L for reliable identification of naïve and memory cell subsets in both CD4 and CD8 T-cell populations among 533 Hiroshima A-bomb survivors. Statistically significant dose-dependent decreases in the percentages of CD45RO−/CD62L+naïve cells were found in the CD8 T-cell population as well as in the CD4 T-cell population. Furthermore, the percentages of CD45RO+/ CD62L+and CD45RO+/CD62L−memory T cells were found to increase significantly with increasing radiation dose in the CD8 T-cell population but not in the CD4 T-cell population. These results suggest that the prior A-bomb exposure has induced long-lasting deficits in both naïve CD4 and CD8 T- cell populations along with increased proportions of these particular subsets of the memory CD8 T-cell population.

Perspectives on cancer immuno-epidemiology

Estimating human cancer risk based on host‐environment interaction is one task of epidemiology, and it has provided indispensable knowledge for prevention of cancer. The recent development of gene‐engineered mice has also provided solid evidence about the relationship between cancer development and immunity. The aim of this review is to discuss the possible contribution of epidemiology to understanding the role of immunity in host defense against cancer, and also to assess the involvement of inflammation in the occurrence of selected cancers. Here we look at the concepts of cancer immunosurveillance and infection‐inflammation‐cancer, and include a brief introduction to recent studies in humans and experimental animal models. It has been postulated for many years that the immune system has the ability to recognize and eliminate nascent transformed cells in the body (so‐called cancer immunosurveillance hypothesis), and this idea has recently obtained strong support from animal experiments. In humans, follow‐up studies among immunosuppressed transplant recipients revealed a remarkably increased risk of not only selected malignancies, but also cancers with no known viral etiology. On the other hand, a prospective cohort study among the general population revealed that individuals with low natural cytotoxic activity of peripheral blood lymphocytes had an increased risk of cancer development. More studies are warranted to allow the construction of a model for the interaction between host immunity, aging, and the environment. The host immune system is also involved in inflammatory responses to pathogen infection: insufficient immune function of the host, or repeated infection, may result in persistent inflammation, where growth/ survival factors continuously act on initiated cells. The combined use of biomarkers will be necessary to define low‐grade persistent inflammation in future cohort studies; and, in addition to these phenotype marker‐based cohort studies, one plausible future direction will be a genomic approach that can be undertaken within cohort studies, looking at the genetic background underlying individual variations in phenotype markers.

Aggressive Natural Killer Cell Leukemia/Lymphoma with N901-Positive:Surface Phenotype: Evidence for the Existence of a Third Lineage in Lymphoid Cells

The morphology, immunologic and functional properties of peripheral blood and bone marrow cells or cultured cells from 2 patients with clinically aggressive non-T, non-B lymphoma/leukemia are described. The leukemic cells possessed medium to large granules in the cytoplasm, antigens against CD38, CD2, CD25, OKIa1, CD16, TA-1, CD9, CD24 and NKH-1 (N901) monoclonal antibodies on their cell surface, and also showed a high natural killer (NK) activity. Phenotypically, the cells in these disorders were quite different from T gamma leukemia cells bearing Fc receptor or the traditionally reported NK leukemia cells possessing HNK-1 (Leu 7) antigens on their surface. In addition, these leukemias/lymphomas belonged to neither T- nor B-cell lineage, proved by studying clonal gene rearrangement for the T beta and T gamma receptor, and immunoglobulin. Hence, a quite interesting and important point, as suggested by our data, is that all our cases expressed an antigen for NKH-1 (N901), which is detectable on all NK cell surfaces and they lacked the antigen for Leu 7 (HNK-1), which is usually detected on the surface of leukemic NK cells. These facts indicate that we are dealing with a leukemic NK cell subset which is quite different from cells of all other reported cases of NK cell leukemias. We therefore concluded that such disorders with an aggressive clinical nature and a poor prognosis as in our cases belong to a new clinical entity originating from a portion of the NK cell subset.(ABSTRACT TRUNCATED AT 250 WORDS)

Increasing of oxidative stress from mitochondria in type 2 diabetic patients

Recent evidence increasingly indicates that oxidative stress may play an important role in the pathogenesis of diabetic vascular complications. Mitochondria has received much attention as an important organ in the generation of oxidative stress. However, the importance of oxidative stress among diabetic patients without vascular complications is unclear.

Estimating the Number of Hematopoietic or Lymphoid Stem Cells Giving Rise to Clonal Chromosome Aberrations in Blood T Lymphocytes

Abstract Nakano, M., Kodama, Y., Ohtaki, K., Itoh, M., Awa, A. A., Cologne, J., Kusunoki, Y. and Nakamura, N. Estimating the Number of Hematopoietic or Lymphoid Stem Cells Giving Rise to Clonal Chromosome Aberrations in Blood T Lymphocytes. Radiat. Res. 161, 273–281 (2004). Quantifying the proliferative capacity of long-term hematopoietic stem cells in humans is important for bone marrow transplantation and gene therapy. Obtaining appropriate data is difficult, however, because the experimental tools are limited. We hypothesized that tracking clonal descendants originating from hematopoietic stem cells would be possible if we used clonal chromosome aberrations as unique tags of individual hematopoietic stem cells in vivo.Using FISH, we screened 500 blood T lymphocytes from each of 513 atomic bomb survivors and detected 96 clones composed of at least three cells with identical aberrations. The number of clones was inversely related to their population size, which we interpreted to mean that the progenitor cells were heterogeneous in the number of progeny that they could produce. The absolute number of progenitor cells contributing to the formation of the observed clones was estimated as about two in an unexposed individual. Further, scrutiny of ten clones revealed that lymphocyte clones could originate roughly equally from hematopoietic stem cells or from mature T lymphocytes, thereby suggesting that the estimated two progenitor cells are shared as one hematopoietic stem cell and one mature T cell. Our model predicts that one out of ten people bears a non- aberrant clone comprising >10% of the total lymphocytes, which indicates that clonal expansions are common and probably are not health-threatening.

Individual Variation of Somatic Gene Mutability in Relation to Cancer Susceptibility: Prospective Study on Erythrocyte Glycophorin A Gene Mutations of Atomic Bomb Survivors

It has previously been reported that hemizygous mutant fraction (Mf) at the glycophorin A (GPA) locus in erythrocytes increased with radiation dose in heterozygotes among Hiroshima and Nagasaki atomic bomb survivors. In the present study, we analyzed the relationship between GPA Mf and cancer risk using newly developed cancers among previously cancer-free subjects whose GPA Mf had been measured between 1988 and 1996. Among 1,723 survivors (1,117 in Hiroshima and 606 in Nagasaki), we identified 186 subjects who developed a first cancer by the end of 2000. We compared the radiation dose responses of GPA Mf between cancer and cancer-free groups using a linear-quadratic model fit by multiple regression analysis in combination with age, sex, and city. The slope of the GPA Mf dose-response curve was significantly higher in the cancer group than in the cancer-free group among Hiroshima subjects. Moreover, no significant difference of GPA Mf between cancer and cancer-free groups was found in unexposed controls in the two cities. The same conclusions were obtained using a linear dose-response model and by further analysis using Cox regression of cancer incidence. These findings suggest that there might be interindividual variation in mutability of somatic genes and that Hiroshima survivors who have higher mutability in response to radiation exposure would be expected to have a higher probability of suffering radiation-related cancer.

Long-lasting changes in the T-cell receptor V beta repertoires of CD4 memory T-cell populations in the peripheral blood of radiation-exposed people

Summary. To study the long‐term effects of radiation‐induced T‐cell depletion on the T‐cell receptor (TCR) Vβ repertoires of human peripheral CD4 T‐cell populations, we measured the percentages of CD4 T cells representing each of the full range of possible TCR Vβ families in a cohort of atomic bomb survivors. We then estimated the extent to which the expression levels for individual TCR Vβ families differed from the average expression level for that particular TCR Vβ family across the entire cohort. We found no evidence of a systematic change in the TCR Vβ repertoires of the naïve CD4 T‐cell populations, but memory CD4 T‐cell TCR Vβ family expression levels diverged significantly from the population average for counterpart families, especially in individuals who had been exposed to higher doses and were at least 20 years of age at the time of the bombing. Comparisons of the TCR Vβ family expression profiles in the naïve and memory CD4 T‐cell pools of the same group of adult survivors revealed that differences in the TCR Vβ repertoires of these two types of CD4 T‐cell pool were larger in more heavily exposed survivors than in unexposed controls. These findings suggest that the memory CD4 T‐cell pools of individuals who received significant radiation doses in adulthood may well have become (and could still be) dependent upon a much less diverse complement of TCR Vβ families than would otherwise have been the case.