Naoyuki Yahata

Telomeric length and telomerase activity vary with age in peripheral blood cells obtained from normal individuals

The telomerase activity and length of telomeres of peripheral blood mononuclear cells obtained from 124 healthy individuals aged 4–95years was measured. Telomerase activity level was semiquantitatively assessed by a fluorescent-telomeric repeat amplification protocol (fluorescent-TRAP) using an internal telomerase assay standard, fluorescent primers and an automated laser fluorescent DNA sequencer. Telomeric length, measured by assay of terminal restriction fragments (TRFs), was determined in HinfI-digested DNA by Southern blot analysis using a (TTAGGG)4 probe. TRF length was determined in 80 individuals and age-related progressive reduction of size was observed. TRF length in peripheral blood mononuclear cells obtained from normal individuals (aged 4–39years) decreased by approximately 84bp per year, while in individuals aged ≥40years it decreased by 41bp per year. In contrast, telomerase activity showed an apparent biphasic pattern with aging. Individuals aged 4–39years showed a progressive decrease in telomerase activity, whereas 65% of those aged ≥40years showed relatively stable but very low telomerase activity, and the remaining individuals aged ≥40years had no detectable telomerase activity. These data obtained from normal individuals might in the future be of value to help risk stratify and manage the care of patients with leukemia.

Telomere dynamics in myelodysplastic syndromes and acute leukemic transformation.

Myelodysplastic syndromes (MDS) are characterized by cytopenias in the blood and dysplastic features in the hematopoietic cells. Although the impact of cytogenetic abnormalities is considerable for prognosis, the exact genetic mechanism of MDS remains undetermined. In this study we assessed cytogenetic changes, microsatellite alterations, and telomere dynamics in order to obtain further insight into the pathogenesis of MDS. Thirty-three percentage of MDS patients and 60% of post-MDS acute leukemia (post-MDS AML) had de novo microsatellite changes. In the MDS phase, however, > 60% of patients showed reduction of telomere lengths without microsatellite changes, indicating that telomere reduction in most MDS patients does not seem to be directly linked to genome instability, or that reduction of telomere length does not induce microsatellite changes in the MDS phase. Some MDS patients had microsatellite changes without telomerase elevation, indicating that genome instability might accumulate during the disease progression in some MDS patients, and this condition (cellular senescence) may be related to ineffective hemopoiesis in MDS patients. In contrast, 40% of post-MDS AML patients had elevated telomerase activity with microsatellite changes, indicating that approximately 40% of patients with post-MDS AML patients had accumulation of genome instability resulting in elevated telomerase activity in an attempt to obtain genetic stability. However, the remaining MDS patients had microsatellite changes without telomerase up-regulation, suggesting that some MDS had genome instability even after leukemic transformation. Most MDS patients with elevated telomerase activity in the AML phase had elevated telomerase activity even in the MDS phase without apparent change in telomere length before and after leukemic transformation. These findings indicate that telomerase activity in the MDS phase may be independent of telomere length, although telomere shortening seems to be related to genomic instability, and this process may be linked to apoptosis of MDS cells.

Membranous glomerulonephritis with nephrotic syndrome associated with chronic lymphocytic leukemia.

A 66-year-old woman was admitted to our hospital for evaluation of edema of the extremities. Laboratory findings suggested that she had nephrotic syndrome and chronic lymphocytic leukemia (CLL). Renal biopsy (with PAM staining) showed a spike formation in the capillary wall. Immunofluorescent staining revealed deposition of immunoglobulin G (IgG) and the third component of complement in the glomerular basement membrane. Electron microscopy showed fibrillary deposits in the subepithelium. These findings indicated membranous glomerulonephritis (MGN). In addition, focal segmental sclerosis and interstitial lymphocytic infiltration were observed in the renal biopsy specimen. In CLL patients nephrotic syndrome occurs rarely. Even if the complication occurs, MGN is not frequent. Both diseases are suspected to occur in association with each other, and immunologic abnormality contributes to their coexistence. Although administration of prednisolone and endoxan improved leukocytosis, proteinuria was not sufficiently improved with combination therapy.

Late Appearance of t(5;12)(q31;p12) in Acute Myeloid Leukemia Associated with Eosinophilia

We report here a case of acute myeloid leukemia with eosinophilia and t(5;12)(q31;p12) at the second relapse. This cytogenetic anomaly is thus associated with one step toward leukemia and eosinophilia.

Interleukin 6 receptor expression by human cord blood- or peripheral blood-derived primitive haematopoietic progenitors implies acquisition of different functional properties

The significance of interleukin 6 receptor (IL‐6R) expression by cord blood (CB)‐ and peripheral blood (PB)‐derived primitive haematopoietic progenitors was investigated. IL‐6R was preferentially expressed by PB‐derived myeloid progenitors. Most PB‐derived erythroid bursts (BFU‐E) and mixed colony‐forming cells (CFU‐Mix) did not express this receptor. However, CB‐derived primitive progenitor cells possessed multipotentiality, irrespective of IL‐6R expression. Interestingly, the long‐term culture‐initiating cell (LTC‐IC) population was enriched in PB‐derived CD34+ IL‐6R+ cells, but the extended LTC‐IC (ELTC‐IC) population, which represents a less mature class of haematopoietic progenitors, seemed to be equally distributed in the IL‐6R+ and IL‐6R− cell populations. In contrast, the number of LTC‐ICs and ELTC‐ICs was similar in CB‐derived CD34+ IL‐6R+ or IL‐6R− cells. It is noteworthy that the number of LTC‐ICs and ELTC‐ICs in CB‐derived CD34+ cells was markedly higher than that in PB‐derived CD34+ cells regardless of IL‐6R expression. Telomerase activity was consistently lower in PB‐derived CD34+ IL‐6R− cells than in CD34+ IL‐6R+ cells. In contrast, telomerase activity was similar in CB‐derived CD34+ IL‐6R+ or IL‐6R− cells. The pattern of telomerase induction upon cytokine stimulation differed between CB‐ and PB‐derived CD34+ IL‐6R+ or IL‐6R− cells. However, overall telomerase activity per dish was well correlated with the proliferative potential of both cell populations, suggesting that induction of telomerase plays an important role in the escape from replicative senescence of primitive haematopoietic progenitors. Collectively, these results suggest that CB‐derived primitive progenitors are less mature than PB‐derived progenitors and that the expression of IL‐6R by primitive haematopoietic progenitors may have different implications for PB‐ and CB‐derived CD34+ cells.

A sole del(15q) anomaly in post-myelodysplasia acute myeloid leukemia

We report the second case of post-myelodysplasia acute myeloid leukemia (post-MDS AML) with a sole chromosome change del(15q). This anomaly is rarely seen. To our knowledge, only seven cases so far have been reported in human neoplasias, including one case each of acute myeloid leukemia (AML), acute lymphoid leukemia, post myelodysplasia AML, myelodysplastic syndrome, myelofibrosis, macroglobulinemia, Hodgkins lymphoma and uterine leiomyoma. This case suggests that del(15q) is related to lympho-myeloproliferative disorders. Moreover, we speculate that certain oncogene(s) located on 15q might have some role in the progression of the disease, since the del(15q) anomaly appeared only in the AML phase in this case.

MALT lymphoma originating in breast and uvula.

A case of marginal zone B cell lymphoma of MALT type arising in the uvula and breast is reported. The patient, a 30-year-old woman who delivered a child and lactated in 1997, was suffering from Sjögren syndrome (SS). She was diagnosed with MALT lymphoma after a biopsy of the right breast and uvula. To investigate the relationship of the delivery, lactation and MALT lymphoma, we examined the immunohistochemical analysis of hormone receptors. As a result, lymphoid cells of the breast were stained with anti-progesterone receptor antibodies in the cytoplasm. Consequently, the MALT lymphoma of the uvula appeared to be associated with SS. Moreover, hormones such as progesterone may have influenced the breast involvement of MALT lymphoma in our case.

Chronic Lymphocytic Leukemia Complicated by Plasmacytoma Originating from Different Clones

In a woman with chronic lymphocytic leukemia (CLL), a plasmacytoma developed on the back region after four years. CLL cases complicated with plasmacytoma are rare. In the present case, the plasmacytoma showed kappa cytoplasmic immunoglobulin (Ig), and the CLL showed gamma lambda surface Ig. To reveal the clonal origin of CLL and plasmacytoma, we analyzed Ig gene rearrangements in the patients peripheral blood and plasmacytoma. Ig gene DNA analysis confirmed the presence of different rearrangements in the heavy and light chain genes of CLL and plasmacytoma. These findings suggest that in this patient, the two B cell malignancies arose from expansion of two phenotypically and genotypically distinct clones.