Hisashi Sohda

Significance of soluble interleukin‐2 receptor levels for evaluation of the progression of adult T‐cell leukemia

Background. The authors conducted a survey of a large cohort of patients with adult T‐cell leukemia (ATL) and a group of human T‐cell leukemia virus type 1 (HTLV‐1) carriers to elucidate whether measurements of soluble interleukin‐2 receptor (sIL‐2R) levels are indicative of ATL tumor burden and correlate with clinical progression.

Phenotypic diversity and prognosis of adult T-cell leukemia

We examined phenotypically 107 patients with adult T-cell leukemia (ATL), using a panel of monoclonal antibodies, in order to clarify the occurrence of aberrant phenotypes, and to determine the correlation between phenotypic diversity and prognosis. The incidence of the typical (CD4+.CD8-) phenotype, the double-negative (CD4-.CD8-), the double-positive (CD4+.CD8+), and the CD8-positive (CD4-.CD8+) phenotypes was 81%, 7%, 7%, and 4%, respectively. The median survival time (MST) for all patients was 10.0 months with 17% survival at 2 years. The patients with typical phenotypes had a 10.2 month MST with 20% survival at 2 years, significantly better than the patients with the unusual phenotypes whose MST were 4.9, 7.8, and 2.6 months, respectively, for the double-negative, double-positive, and CD8-positive phenotypes. Lack of antigens reactive with CD2, CD3, CD5, and WT31 monoclonal antibody panels was one factor in bad prognosis, but the presence of CD4 and CD8 antigen abnormalities was much more significant.

Characteristics of chemotherapy-induced clinical remission in long survivors with aggressive adult T-cell leukemia/lymphoma

The acute and lymphoma types of adult T-cell leukemia/lymphoma (ATL) usually have a very poor prognosis, although some patients achieve long survival after chemotherapy. A total of 114 patients with these aggressive types of ATL were newly diagnosed at our institution from 1975 to 1989. By multivariate analysis, poor performance status and high serum creatine levels were associated with shortened survival. With combination chemotherapy, 20 patients achieved complete remission (CR), 53 achieved partial remission (PR) and 35 showed no response. Fifteen of the CR or PR patients survived for more than two years and all other patients survived for less than two years. As compared with short survivors (< 2 years) after remission, long survivors (> or = 2 years) after remission had a higher CR/PR ratio, a longer time until remission and a higher doxorubicin dose to achieve remission. Death due to causes other than the primary disease occurred in 18% of short survivors after remission and in 11.2% of nonresponders, but in none of the long survivors. Long survivors with acute ATL included 6 patients with CR and 5 patients with PR. All four lymphoma type ATL long survivors achieved CR. Monoclonal integration of HTLV-I provirus was detected in the peripheral blood mononuclear cells of all 3 PR long survivors with acute ATL studied, but was not detected in all 4 CR cases studied at remission. The minimum CD4/CD8 ratio of peripheral mononuclear cells at remission was < 1.0 in all acute ATL long survivors with CR, and was > 1.0 in all acute ATL long survivors with PR. Three out of six acute ATL long survivors with CR developed suspected viral infection just before achieving CR. Our findings show that in aggressive ATL the characteristics of remission are heterogeneous even among long survivors.

Establishment and characterization of a new erythropoietin-dependent acute myeloid leukemia cell line, AS-E2.

We have established an erythropoietin-dependent human leukemia cell line, AS-E2, from a patient with acute myeloid leukemia. These cells have many characteristics of late erythroid progenitor cells, they are positive for CD36, Glycophorin A, and CD71 but negative for CD41, and positive for benzidine and PAS staining. These cells express GATA-1 and have low affinity erythropoietin (EPO) receptor on their surface. Interestingly, AS-E2 cells are strictly dependent on EPO for their growth and survival; other cytokines including GM-CSF, stem cell factor, or IL-3 cannot support the growth of this cell line. These features are similar to late erythroid lineage cells, like normal BFU-E or CFU-E, and we have demonstrated that EPO stimulation induces the tyrosine phosphorylation of several proteins in AS-E2 cells including the EPO receptor and JAK2 kinase. This new cell line is a useful reagent to study biological and molecular events during the late stages of erythropoiesis, and to understand transforming events in human erythroid cells.

Prognostic significance of the proportion of Ki‐67‐positive cells in adult t‐cell leukemia

The authors examined peripheral blood samples from patients with adult T‐cell leukemia (ATL) using the monoclonal antibody Ki‐67 which detects a nuclear antigen present in actively proliferating cells. In patients with chronic ATL, the percentage of Ki‐67‐positive cells was significantly lower than in acute ATL patients (median values, 3.3% versus 18.9%, P < 0.001). Furthermore, there was a significant inverse correlation between the percentage of Ki‐67‐positive cells and the length of survival (P < 0.001). Serum lactic dehydrogenase (LDH) levels also showed a significant inverse correlation with survival, but this was less strong than that for Ki‐67 (0.01 < P < 0.02). Thus, Ki‐67 positivity appears to indicate the aggressiveness of ATL, and can possibly be used for the clinical classification of ATL patients as well as for the prediction of prognosis.

Established IL‐2‐dependent double‐negative (CD4‐ CD8‐) TCRαβ/CD3+ ATL cells: induction of CD4 expression

Summary. We established IL‐2‐dependent T cells from an adult T‐cell leukaemia (ATL) patient whose leukaemic cells changed from CD4 single‐p‐positive in the initial phase to double‐negative (CD4‐ CD8‐) at the time of exacerbation. The cells termed SO‐4 were of ATL cell origin and showed the double‐negative TCRαβ/CD3+ T‐cell phenotype. SO‐4 cells acquired CD4 antigen expression following stimulation with concanavlin A (ConA) or immobilized anti‐CD3 antibody. The induction was inhibited by herbimycin A, an inhibitor of protein tyrosine kinase (PTK) activity. No CD4 mRNA was detectable in unstimulated SO‐4 cells but a 3.0 kb signal specific for CD4 mRNA was detected after stimulation. These findings indicate that SO‐4 cells return to their original phenotype (CD4 single‐positive) by stimulation involving PTK. The results indicate that there is a pathway of phenotypic cycling between CD4 single‐positive and double‐negative T cells.

Frequent Hepatic Involvement in Adult T Cell Leukemia: Comparison with non-Hodgkin's Lymphoma

We examined 111 patients with acute type- or lymphoma type-adult T-cell leukemia (ATL) and compared them with 106 patients with non-Hodgkins lymphoma (NHL). In addition to skin involvement and hypercalcemia which are already known to be frequent in ATL, ATL patients showed an higher incidence of hepatic involvement. There was more frequent palpable hepatomegaly, higher total bilirubin, GOT, GPT, lactate dehydrogenase (LDH), and alkaline phosphatase values in ATL than in NHL patients (p < 0.0001). Among 36 autopsied liver samples, invasion of ATL cells was confirmed in 22 cases. ATL patients with impaired hepatic function showed shorter survival times than patients without hepatic dysfunction. Moreover, ATL patients showed a worse performance status (PS), a higher incidence of lytic bone lesions, lower total protein (TP) and serum albumin levels than NHL patients. This invasive characters of ATL cells and consequent impaired general condition seemed to be factors affecting the poor prognosis recorded in ATL.

DNA aneuploidy of adult T-cell leukemia cells

To clarify the biological characteristics of adult T-cell leukemia (ATL), immunophenotyping and DNA aneuploid analysis were performed in 72 ATL cases, using flow cytometric techniques. DNA aneuploidy was found in 45 cases (62.5%); the DNA index ranged from 1.03 to 2.16 (mean: 1.24). The incidence of aneuploidy in smoldering, chronic, acute, and lymphoma ATL subtypes was 20.0%, 46.6%, 76.3%, and 77.8%, respectively. The aneuploid patients had a greater tumor burden (adenopathy, hepatosplenomegaly, and leukocytosis with ATL cells), a higher level of serum LDH, and a higher incidence of hypercalcemia, compared with the diploid group. Further, unusual aberrant immunophenotypes were identified predominantly in the aneuploid group. Patients with aneuploidy had a 7.6 month median survival time (MST) with a 2 year survival rate of 24.6%, significantly worse than in the patients with diploidy, whose MST was 25.4 months with a 2 year survival of 60.1%. In some aneuploid patients, the disease often progresses from a static to an aggressive form. Thus, the determination of aneuploidy and unusual immunophenotype should be useful for detecting clinical behavior and for monitoring ATL patients, particularly in regard to such progression.

Unusual Morphological Features of Adult T-cell Leukemia Cells with Aberrant Immunophenotype

We describe 4 cases of adult T-cell leukemia (ATL) with unusual morphology and aberrant immunophenotype. All patients were Japanese and born in the Nagasaki district, an area endemic for HTLV-I. Peripheral blood and/or bone marrow films revealed bizarre giant cells with and without large nucleoli; the cells were 5 to 6 times the diameter of erythrocytes, resembling Hodgkins cells. Some peripheral blood cells were morphologically similar to prototypic ATL cells, while many other cells in the bone marrow showed unusual morphology. Furthermore, leukemic cells had aberrant immunophenotypes such as the CD8-positive type in patients 1 and 2, the CD4-.CD8- double-negative type in patient 3, and the CD5 antigen defect in patient 4. All patients had marked elevations of the serum calcium and LDH and organomegaly, while all had a short survival. Anti-HTLV-I antibodies and provirus DNA monoclonality were demonstrated in all patients. The results suggested that the unusual morphology and aberrant ATL cell immunophenotype may be indicative of a high grade malignant behaviour of ATL.

Multi-clonal expansion of unique human T-lymphotropic virus type-I-infected T cells with high growth potential in response to interleukin-2 in prodromal phase of adult T cell leukemia

We established a simple IL-2-dependent colony-forming assay for T cells infected with human T-lymphotropic virus type-I (HTLV-I). IL-2-dependent cell lines were subsequently established by expanding individual colonies in liquid cultures. Lymphocyte-rich fractions were prepared from 31 HTLV-I carriers, 12 patients with smoldering ATL, 11 chronic ATL, 12 crisis ATL and 10 acute ATL. Primary colonies of CD4+ p19+ T cells were formed in all cases of carriers, smoldering and chronic ATL, and in 10 of 12 crisis cases. In contrast, no colony was formed from cells of patients with acute ATL. The rate of establishment of cell lines in HTLV-I carriers was significantly lower than that in patients of prodromal phase ATL. Cell lines established from cells of three prodromal cases were clonally identical to the parent ATL cells, while others had clonally distinct cell lines. Our results indicated the presence of four components of HTLV-I-infected T cells: (1) normal carrier T cells capable of forming colonies but not cell lines; (2) pre-malignant T cells capable of forming colonies as well as cell lines; (3) malignant T cells capable of forming colonies as well as cell lines; (4) fully malignant T cells unresponsive to IL-2. Our results suggest the presence of a multiclonal expansion of unique T cells in the prodromal phase of ATL, which have a high growth potential in response to IL-2. The coexistence of multiclonality with a dominant ATL clone may be closely related to the underlying pathology in HTLV-I leukemogenesis.