Lev Shvidel

IL-8 secreted in a macrophage migration-inhibitory factor- and CD74-dependent manner regulates B cell chronic lymphocytic leukemia survival

Chronic lymphocytic leukemia (CLL) is a malignant disease of small mature lymphocytes. Previous studies have shown that CLL B lymphocytes express relatively large amounts of CD74 mRNA relative to normal B cells. In the present study, we analyzed the molecular mechanism regulated by CD74 in B-CLL cells. The results presented here show that activation of cell-surface CD74, expressed at high levels from an early stage of the disease by its natural ligand, macrophage migration-inhibition factor (MIF), initiates a signaling cascade that contributes to tumor progression. This pathway induces NF-κB activation, resulting in the secretion of IL-8 which, in turn, promotes cell survival. Inhibition of this pathway leads to decreased cell survival. These findings could form the basis of unique therapeutic strategies aimed at blocking the CD74-induced, IL-8- dependent survival pathway.

Primary effusion lymphoma (PEL) in HIV-negative patients--a distinct clinical entity.

Primary effusion lymphoma (PEL) is a recently described rare type of non-Hodgkins lymphoma occurring almost exclusively in HIV infected people. Human herpesvirus 8 (HHV-8), has been linked with PEL, and a causative relationship has been suggested. In the vast majority of PEL cases Epstein-Barr virus (EBV) has been found in the tumour cells. We describe here an elderly human immune deficiency (HIV) seronegative man with intractable chest pain and pleural effusion. The diagnosis of malignant lymphoma was suggested cytologically and confirmed histologically following pleural biopsy. No lymphadenopathy or organ involvement with lymphoma was found. Systemic chemotherapy with a modified CHOP regimen with G-CSF support gradually led to the resolution of the chest pain and ultimately resulted in a complete clinical remission (CCR). The presence of HHV-8 was demonstrated by PCR using paraffin-embedded tissue samples from the involved pleura, whereas EBV-associated genetic material was absent. The patient remained in CCR for 18 months and died of an unrelated cause (cerebrovascular event). Only 11 other cases with clinical and virological features similar to those of our patient have been reported in the literature. Analysis of these rare cases suggests HIV-negative EBV-negative PEL to be a distinct clinical entity with epidemiological features resembling classical KS and supports an EBV-independent role for HHV-8 in the pathogenesis of PEL.

TAp63 Regulates VLA-4 Expression and Chronic Lymphocytic Leukemia Cell Migration to the Bone Marrow in a CD74-Dependent Manner

The hallmark of chronic lymphocytic leukemia (CLL) is the relentless accumulation of mature lymphocytes, mostly due to their decreased apoptosis. CD74 was recently shown to serve as a survival receptor on CLL cells. In this study, we show that stimulation of CD74 with its natural ligand, migration inhibitory factor, initiates a signaling cascade that results in upregulation of TAp63, which directly regulates CLL survival. In addition, TAp63 expression elevates the expression of the integrin VLA-4, particularly during the advanced stage of the disease. Blocking of CD74, TAp63, or VLA-4 inhibits the in vivo homing of CLL cells to the bone marrow (BM). Thus, CD74 and its target genes TAp63 and VLA-4 facilitate migration of CLL cells back to the BM, where they interact with the supportive BM environment that rescues them from apoptosis. These results could form the basis of novel therapeutic strategies aimed at blocking homing of CLL cells in their return to the BM and attenuating their survival.

Conventional dose fludarabine-based regimens are effective but have excessive toxicity in elderly patients with refractory chronic lymphocytic leukemia.

The best approach to elderly patients with relapsing chronic lymphocytic leukemia (CLL) or disease refractory to conventional therapy with alkylating agents has not yet been established. Fludarabine and its combination with mitoxantrone and/or cyclophosphamide, which is the most effective treatment in younger patients, has not been extensively utilized in the elderly CLL. Here we report our results with fludarabine-based chemotherapy in 32 previously treated patients over the age of 65 years. The overall response rate was 59% with no complete remission, 3 nodular partial remissions and 16 partial remissions. The median time to progression of disease was 7 months. Only 10 patients completed the entire treatment program, because of poor compliance due to toxicity. Eight patients developed neutropenic fever, 14 severe bacterial infections and 2 patients showed progressive encephalopathy. For comparison, in a younger group of patients with refractory CLL (<65 years), 38 of 50 patients completed the treatment plan, and the ORR was 80% (10 CR, 11 PR-nodular, 19 PR) with a median response of 12 months. Neutropenic fever was diagnosed in 10 and severe bacterial infection in 4 patients. In conclusion, fludarabine-based chemotherapy is effective for refractory CLL, however, excessive toxicity such as severe infections and neurological complications, do not allow completion of treatment in the majority of the elderly patients. Because maintenance of a good quality of life should be the main goal in the elderly CLL population, dose reduction of fludarabine and the appropriate use of myeloid growth factors and prophylactic antibiotics appear mandatory in this group of patients.

The Cytokine Midkine and Its Receptor RPTPζ Regulate B Cell Survival in a Pathway Induced by CD74

Lasting B cell persistence depends on survival signals that are transduced by cell surface receptors. In this study, we describe a novel biological mechanism essential for survival and homeostasis of normal peripheral mature B cells and chronic lymphocytic leukemia cells, regulated by the heparin-binding cytokine, midkine (MK), and its proteoglycan receptor, the receptor-type tyrosine phosphatase ζ (RPTPζ). We demonstrate that MK initiates a signaling cascade leading to B cell survival by binding to RPTPζ. In mice lacking PTPRZ, the proportion and number of the mature B cell population are reduced. Our results emphasize a unique and critical function for MK signaling in the previously described MIF/CD74-induced survival pathway. Stimulation of CD74 with MIF leads to c-Met activation, resulting in elevation of MK expression in both normal mouse splenic B and chronic lymphocytic leukemia cells. Our results indicate that MK and RPTPζ are important regulators of the B cell repertoire. These findings could pave the way toward understanding the mechanisms shaping B cell survival and suggest novel therapeutic strategies based on the blockade of the MK/RPTPζ-dependent survival pathway.

B-Cell Prolymphocytic Leukemia: A Survey of 35 Patients Emphasizing Heterogeneity, Prognostic Factors and Evidence for a Group with an Indolent Course

We report a retrospective survey of 35 patients (18 males and 17 females) with B-Prolymphocytic leukemia (B-PLL) followed for a median of 63 months. Twelve patients fulfilled Galtons original clinical and hematological criteria, presented with prominent splenomegaly and hyperleukocytosis and showed rapid progression soon after diagnosis. Twelve cases with gradually increasing spleen size and prolymphocyte count had an indolent course. Seven of this group are alive 68 to 164 months after diagnosis, whereas five died from causes unrelated to PLL. Eleven patients who never developed impressive leukocytosis had a variable prognosis. In the group of 17 patients treated with chlorambucil and prednisone (CP) or cyclophosphamide, vincristine, prednisone (COP) 8 achieved a partial remission (PR) with a median response of 32 months. In the group of six cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) treated patients one achieved a complete remission and two PR (median response was maintained for 30 months). Three patients treated with 2CdA achieved good PR. Six patients remained untreated. Median survival was 65 months and the probability of overall survival for 3, 5, and 10 years was 63%, 56% and 35%, respectively. Anemia < 11 g/dl and lymphocytosis > 100 x 10(9)/l were predictors of shorter survival in this group of patients. Age over 70, gender, B-symptoms at presentation, spleen size, thrombocytopenia, low IgG and complement levels, presence of paraproteinemia and the pattern of bone marrow infiltrate were not significant. Our findings show that all B-PLL may not have such a poor prognosis as described in earlier reports. The existence of prior symptoms evolving gradually after years to obvious PLL and cases with mild prolymphocytosis could possibly lead to underdiagnosis of the entity. Identification and follow-up of such cases may suggest a different natural history, variable prognostic features and different survival curves for B-PLL patients. In the light of the above, we suggest that the therapeutic approach for B-PLL should always relate to the severity of the disease.

Busulphan is safe and efficient treatment in elderly patients with essential thrombocythemia

Busulphan is safe and efficient treatment in elderly patients with essential thrombocythemia

Polyclonal Reactive Peripheral Blood Plasmacytosis Mimicking Plasma Cell Leukemia in a Patient with Staphylococcal Sepsis

A 41-year-old man presented with rhabdomyolysis and sepsis while the peripheral blood smear showed a pseudo-leukemic picture of plasma cells. After starting supportive therapy, the morphologic finding disappeared within 24 h.

Rapamycin and curcumin induce apoptosis in primary resting B chronic lymphocytic leukemia cells

B chronic lymphocytic leukemia (B-CLL) cells exist in patients as slowly accumulating resting as well as proliferating B cells. In this study, we examined whether Rapamycin and Curcumin, two naturally occurring compounds shown to have apoptotic effects, could selectively induce apoptosis in resting B-CLL cells. Mononuclear cells isolated from patients with B-CLL were treated with these agents and analysed by AnnexinV/propidium iodide binding, caspase activity, and changes in bcl-2/Bax ratio. Rapamycin and curcumin significantly induced apoptosis in resting B-CLL cells obtained from patients with CLL. Furthermore, rapamycin and curcumin increased caspase 9, 3 and 7 activity, decreased anti-apoptotic bcl-2 levels, and increased the pro-apoptotic protein Bax. These data suggest rapamycin and curcumin may be an effective treatment for B-CLL and are of high clinical significance considering the growing population of patients and lack of efficient treatment for this malignant disease.

Acute basophilic leukaemia: eight unsuspected new cases diagnosed by electron microscopy.

Summary. We report eight new patients with de novo acute basophilic leukaemia (ABL) diagnosed by electron microscopy (EM) in 184 patients with poorly differentiated AML who were selected for ultrastructural analysis between the years 1989 and 2002. Morphology by light microscopy, cytochemistry, immunophenotyping and cytogenetics did not enable an accurate diagnosis in any of these patients. In almost all the patients, the blasts showed reactivity for HLA‐DR and CD34. EM studies demonstrated the presence of basophilic granules in the leukaemic blasts. These granules were membrane bound and their contents varied in appearance from uniformly electron dense to partially speckled or electron lucent. Theta granules were present in only three patients and no mast‐cell type granules were observed. By light microscopy, the myeloperoxidase reaction was positive in three patients in an unusual coarse granular pattern. Ultrastructural demonstration of peroxidase in the granules, nuclear membrane and profiles of endoplasmic reticulum was observed in all eight patients. The reaction in the granules showed a particular speckled pattern. The outcome was unfavourable in six of our eight patients. As a definitive diagnosis of ABL may be made only by EM, we suggest including such studies as an integral part of the diagnostic work‐up of acute leukaemia cases that lack differentiation markers.