Rapid reconstitution of functionally active 6-sulfoLacNAc(+) dendritic cells (slanDCs) of donor origin following allogeneic haematopoietic stem cell transplant.

The role of dendritic cells (DCs) and macrophages in allogeneic haematopoietic stem cell transplant (HSCT) is critical in determining the extent of graft-versus-host response. The goal of this study was to analyse slanDCs, a subset of human proinflammatory DCs, in haematopoietic stem cell (HSC) sources, as well as to evaluate their 1-year kinetics of reconstitution, origin and functional capacities in peripheral blood (PB) and bone marrow (BM) of patients who have undergone HSCT, and their presence in graft-versus-host disease (GVHD) tissue specimens. slanDCs were also compared to myeloid (m)DCs, plasmacytoid (p)DCs and monocytes in HSC sources and in patients' PB and BM throughout reconstitution. slanDCs accounted for all HSC sources. In patients' PB and BM, slanDCs were identified from day +21, showing median frequencies comparable to healthy donors, donor origin and kinetics of recovery similar to mDCs, pDCs, and monocytes. Under cyclosporin treatment, slanDCs displayed a normal pattern of maturation, and maintained an efficient chemotactic activity and capacity of releasing tumour necrosis factor (TNF)-α upon lipopolysaccharide (LPS) stimulation. None the less, they were almost undetectable in GVHD tissue specimens, being present only in intestinal acute GVHD samples. slanDCs reconstitute early, being donor-derived and functionally competent. The absence of slanDCs from most of the GVHD-targeted tissue specimens seems to rule out the direct participation of these cells in the majority of the local reactions characterizing GVHD.

Role of stromal cell-mediated Notch signaling in CLL resistance to chemotherapy.

Stromal cells are essential components of the bone marrow (BM) microenvironment that regulate and support the survival of different tumors, including chronic lymphocytic leukemia (CLL). In this study, we investigated the role of Notch signaling in the promotion of survival and chemoresistance of human CLL cells in coculture with human BM-mesenchymal stromal cells (hBM-MSCs) of both autologous and allogeneic origin. The presence of BM-MSCs rescued CLL cells from apoptosis both spontaneously and following induction with various drugs, including Fludarabine, Cyclophosphamide, Bendamustine, Prednisone and Hydrocortisone. The treatment with a combination of anti-Notch-1, Notch-2 and Notch-4 antibodies or γ-secretase inhibitor XII (GSI XII) reverted this protective effect by day 3, even in presence of the above-mentioned drugs. Overall, our findings show that stromal cell-mediated Notch-1, Notch-2 and Notch-4 signaling has a role in CLL survival and resistance to chemotherapy. Therefore, its blocking could be an additional tool to overcome drug resistance and improve the therapeutic strategies for CLL.

High serum levels of B-lymphocyte stimulator are associated with clinical-pathological features and outcome in classical Hodgkin lymphoma.

B-lymphocyte stimulator (BLyS) acts as survival factor for B lymphocytes. As Hodgkin and Reed-Sternberg (HRS) cells express receptors through which BLyS promotes their growth and chemotherapy resistance, we investgated whether this molecule was increased in sera from patients with classical Hodgkin lymphoma (cHL) and whether it correlates with clinical-pathological features and outcomes. Enzyme-linked immunosorbent assay was used to measure soluble BLyS (sBLyS) in sera from 87 patients and 33 donors; higher levels were detected in patients (mean +/- standard error 4493.9 +/- 264.9 pg/ml vs. 2687.0 +/- 200.9 pg/ml; P < 0.0001). Levels above the median value (4242.0 pg/ml) were associated with age > or = 45 years (P = 0.042), advanced stages of disease (P = 0.005), systemic symptoms (P = 0.014) and extranodal involvement (P = 0.009). Five-year failure-free survival (FFS) of patients with sBLyS below or equal to median levels was 88.6% as compared to 65.1% of those with levels above the median (P = 0.009). Statistical analyses confirmed the prognostic significance of sBLyS (P = 0.046). When patients were analysed according to variables associated with high levels, sBLyS showed an independent predictive power in terms of FFS. Our findings support the involvement of BLyS in cHL pathogenesis. The association between high serum levels and an inferior FFS indicates that sBLyS is a possible prognostic predictor with a potential significance as a therapeutic target.

ZAP-70 expression, as detected by immunohistochemistry on bone marrow biopsies from early-phase CLL patients, is a strong adverse prognostic factor.

Zeta-associated protein-70 (ZAP-70), mostly assessed by flow-cytometry (FC), recently emerged as reliable prognostic factor in chronic lymphocytic leukaemia (CLL) at presentation. We evaluated ZAP-70 expression in 156 CLL patients by immunohistochemistry (IHC) on formalin-fixed bone marrow (BM) biopsies at diagnosis. At presentation, 117 patients (75%) were with Binet stage A, 27 (17%) stage B and 12 (8%) stage C. Median follow-up was 61 months (range 6-242). ZAP-70 was expressed in neoplastic lymphocytes of 69 patients (44%). Concordance between ZAP-70 by IHC and ZAP-70 by FC, immunoglobulin heavy chain variable genes (IGHV) mutational status and CD38 expression was found in 41/46 (89%), 41/49 (80%) and in 60/88 (68%) tested cases, respectively. ZAP-70 expression significantly correlated with advanced Binet stage (B-C), diffuse BM infiltration, increased lactate dehydrogenase (LDH) and beta2-microglobulin serum levels and lymphocyte doubling time <12 months. ZAP-70 positivity was significantly related to poorer time to progression (median 16 months vs 158 of ZAP-70-negative cases) (P<0.0001) and overall survival (median 106 months vs not reached) (P=0.0002); this correlation was confirmed at multivariate analysis. ZAP-70 expression correlated with poorer outcome also when evaluated only in the 117 stage A patients. In conclusion, immunohistological detection of ZAP-70 on formalin-fixed BM biopsies at diagnosis appears a useful methodological approach to identify patients with poor prognosis in CLL.

Distinctive natural history in hepatitis C virus positive diffuse large B-cell lymphoma: analysis of 156 patients from northern Italy.

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) has been correlated to hepatitis C virus (HCV) infection in few series, but characteristics and outcome of these patients remain undefined. PATIENTS AND METHODS: We analyzed 156 previously untreated consecutive HCV-positive patients with DLBCL observed between 1994 and 2004 in three major institutions from northern Italy. RESULTS: Median age at presentation was 63 years and 8% of patients had DLBCL transformed from low-grade lymphomas. Spleen was the most frequently involved extranodal site, followed by liver and stomach. Treatment was delivered with cure-intent in 132 patients, while the remaining 24 patients received monochemotherapy or radiotherapy alone due to old age or seriously impaired hepatic function. Only five patients (4%) had to discontinue chemotherapy due to severe liver function impairment. The addition of rituximab did not seem to affect patients' tolerance to treatment. Five-year overall survival of the entire cohort was 72%, while 5-year progression-free survival (PFS) of the 132 patients treated with cure-intent was 51%. Hepatitis B virus co-infection, advanced Ann Arbor stage and nodal origin of the tumor resulted the strongest adverse prognostic factors. CONCLUSIONS: Patients with HCV-positive DLBCL share distinctive clinical features. Future studies should prospectively evaluate the association between HCV and aggressive lymphomas.

beta(2)-microglobulin in Hodgkin's lymphoma: prognostic significance in patients treated with ABVD or equivalent regimens.

PURPOSE: Serum beta-2 microglobulin (sbeta(2)m) is an established prognostic factor for several lymphoproliferative disorders. Because its significance in Hodgkin's lymphoma (HL) is controversial, we determined sbeta(2)m levels in pretreatment serum samples of patients with HL in order to elucidate its prognostic value in this condition. PATIENTS AND METHODS: Pretreatment sbeta(2)m levels were determined in 379 HL patients who were treated with ABVD or equivalent regimens with or without radiotherapy (RT), using a radioimmunoassay (upper normal limit 2.4 mg/l). Sbeta(2)m levels were correlated with several clinical and laboratory parameters. RESULTS: Elevated sbeta(2)m levels were detected in 138/379 (36%) patients and correlated with all clinical and laboratory baseline features except gender, lung involvement and mediastinal bulk. They also correlated with serum soluble CD30 and interleukin-10 levels. The 8-year failure-free survival (FFS) was 78 -/+ 4% for patients with normal versus 65 -/+ 7% for patients with elevated sbeta(2)m levels (p=0.003). The corresponding rates among early-stage patients were 83 -/+ 53% versus 71 -/+ 9% (p=0.003), while for advanced stages they were 70 -/+ 6% versus 64 -/+ 8% (p=0.54). In multivariate analysis of the whole patient population elevation of sbeta(2)m levels was not predictive of FFS, but it was strongly predictive among early-stage patients. The 8-year overall survival (OS) rates were 91 -/+ 3% for patients with normal versus 59 -/+ 11% (p <0,0001) for patients with elevated sbeta(2)m levels, while unrelated mortality at 8 years was 1 -/+ 1% versus 27 -/+ 12% (p<0.0001). CONCLUSION: Our data suggest that sbeta(2)m levels may be a potent prognostic factor for FFS in patients with early stage HL treated with ABVD and equivalent regimens. Their effect on OS is confounded by the higher unrelated mortality in patients with elevated baseline sbeta(2)m levels, probably due to the strong association between sbeta(2)m and older age.

Primary mediastinal large B-cell lymphoma (PMLBCL): long-term results from a retrospective multicentre Italian experience in 138 patients treated with CHOP or MACOP-B/VACOP-B.

The optimal treatment of primary mediastinal large B-cell lymphoma (PMLBCL) is still undefined. In the absence of randomised studies, we retrospectively analysed: (a) the effectiveness of two chemotherapy regimens (CHOP vs MACOP-B/VACOP-B) in complete remission (CR) achievement and event-free survival (EFS) and (b) the role of mediastinal involved-field radiotherapy (IF-RT) as consolidation. From 1982 to 1999, 138 consecutive patients affected by PMLBCL were treated in 13 Italian institutions with CHOP (43) or MACOP-B/VACOP-B (95). The two groups of patients were similar as regard to age, gender, presence of bulky mediastinal mass, pleural effusion, stage and international prognostic indexes category of risk. Overall, 75.5% of patients in CR received IF-RT as consolidation. Complete remission was 51.1% in the CHOP group and 80% in MACOP-B/VACOP-B (P<0.001). Relapse occurred in 22.7% of CHOP- and in 9.2% of MACOP-B/VACOP-B-treated patients (n.s.). Event-free patients were 39.5% in CHOP and 75.7% in the MACOP-B/VACOP-B group (P<0.001). The addition of IF-RT as consolidation improved the outcome, irrespectively of the type of chemotherapy (P=0.04). At a multivariate analysis, achievement of CR (P<0.0001) and type of CT (MACOP-B/VACOP-B) retained the significance for OS (P=0.008) and EFS (P=0.03). In our experience, MACOP-B/VACOP-B appears to positively influence OS and EFS in patients affected by PMLBCL, as compared to CHOP. Consolidation IF-RT on mediastinum further improves the outcome of CR patients.

Serum levels of soluble CD30 improve International Prognostic Score in predicting the outcome of advanced Hodgkin's lymphoma.

BACKGROUND: The International Prognostic Score (IPS) and circulating levels of the soluble form of CD30 molecule (sCD30) have both been associated with poor outcome in patients with advanced Hodgkin's lymphoma (HL). The aim of this study was to assess the prognostic power of the combined evaluation of sCD30 and IPS in these patients. PATIENTS AND METHODS: We included 101 patients with advanced HL, treated with ABVD (doxorubicin, bleomycin, vinblastine and dacarbazine) or MOPP (mechlorethamine, vincristine, procarbazine and prednisone)/ABVD chemotherapy with or without radiotherapy. All were tested for pre-treatment sCD30 levels. RESULTS: Six-year estimated overall survival (OS) and failure-free survival (FFS) was 89% +/- 3% and 75% +/- 4%, respectively. Thirty-three patients (33%) had IPS >2; their FFS was 60% compared with 82% in the remaining patients (P = 0.027). Serum sCD30 levels were > or =100 U/ml in 41 (41%) patients; their FFS at 6 years was 58%, compared with 87% in patients with sCD30 <100 U/ml (P = 0.003). In the 18 patients with both sCD30 > or =100 U/ml and IPS >2, FFS was significantly worse (44%) than in patients with low sCD30 and low IPS (89%) (P <0.001) or with only one of the two adverse prognostic factors (73%) (P = 0.03). CONCLUSIONS: In our study, the combination of IPS >2 and serum sCD30 levels > or =100 U/ml identifies a sizeable subgroup (18%) of advanced HL patients with very poor FFS, who might take advantage of intensified up-front treatment strategies.

Role of CD30+ T cells in rheumatoid arthritis: a counter-regulatory paradigm for Th1-driven diseases.

CD30 has been proposed to identify Th0/2-type clones. However, the in vivo relevance of this finding is still a matter of debate, as high serum levels of soluble CD30 have been found in both Th1- and Th2- dominated disorders. Among these, rheumatoid arthritis represents a condition where the Th1 predominance is combined with the presence of CD30(+) T-cell activity, particularly in specific stages of the disease. This article discusses the hypothesis that CD30(+) T cells might play a counter-regulatory role at sites of inflammation in Th1-mediated conditions, such as rheumatoid arthritis.

Serum interleukin-10 levels are an independent prognostic factor for patients with Hodgkin's lymphoma.

BACKGROUND AND OBJECTIVES: Interleukin-10 (IL-10) is a pleiotropic cytokine which increases bcl-2 levels and protects cells from steroid or doxorubicin-induced apoptosis. Hodgkin and Reed-Sternberg (HRS) cells bear functional IL-10 receptors. Thus serum IL-10 (sIL-10) might inhibit apoptosis in HRS cells, which could occur as a result of either chemotherapy or the crippled immunoglobulin genes. DESIGN AND METHODS: We determined sIL-10 levels in 122 patients with Hodgkin's lymphoma (HL), treated with ABVD or equivalent regimens with or without radiotherapy, and correlated them with presenting clinical and laboratory features, as well as failure-free survival (FFS) and overall survival. RESULTS: Elevated sIL-10 levels ( > or = 10 pg/mL) were detected in 55 patients (45%), and were correlated with advanced stage and elevated serum b2-microglobulin levels. At 7 years FFS was 85% vs. 63% for patients with normal vs. elevated sIL-10 levels, respectively (p=0.01); overall survival was 97% vs. 73% (p=0.005). Multivariate analysis with Cox's proportional hazards model demonstrated that elevated sIL-10 levels were the strongest independent predictor of FFS, and were also associated with inferior overall survival. INTERPRETATION AND CONCLUSIONS: We conclude that sIL-10 levels are elevated in 45% of patients with HL, and are associated with inferior FFS and overall survival, independently of other established prognostic factors.

Low expression of p27 and low proliferation index do not correlate in hairy cell leukaemia.

The molecular basis accounting for the peculiar clinical and biological features of hairy cell leukaemia (HCL) is currently unknown. Deregulation of cell cycle genes plays a significant role in oncogenesis and there is considerable evidence suggesting that Cdk inhibitors (Ckis) function as tumour suppressors. We and others have recently demonstrated low expression of Cki p27 in very aggressive neoplasms and high-grade lymphomas. To investigate whether HCL cases express normal p27 protein, as in other low-grade lymphomas with a low proliferation index, 58 cases of HCL were characterized using a sensitive biotin-streptavidin-immunoperoxidase technique and specific antibodies against p27. All HCL cases showed either no or very weak reactivity, in contrast to other types of low-grade B-cell lymphoma [22 cases of chronic lymphocytic leukaemia (CLL), 12 cases of gastric marginal B-cell lymphoma (MALT), 16 cases of follicular lymphomas and two cases of splenic marginal zone lymphomas]. To investigate the possible mechanism(s) accounting for the low p27 expression observed in hairy cells, multiple approaches were used. According to these molecular studies, low levels of p2 7 are not as a result of (1) increased ubiquitin-mediated degradation, (2) decreased levels of p27 transcription or (3) p27 somatic mutations and/or allelic loss. These findings suggest that low p27 protein expression in HCL may be achieved through post-transcriptional regulation. Finally, our data demonstrate that p27 expression in HCL does not correlate with either cell cycle progression or proliferation index, suggesting that low levels of p27 in hairy cells may be associated with their unique stage of B-cell differentiation and/or the activation of as yet unknown pathways.

Transplantation potential of peripheral whole blood primed by VACOP-B chemotherapy plus filgrastim (r-metHuG-CSF) in patients with aggressive non-Hodgkin's lumphoma.

Large volumes of peripheral blood need to be processed to obtain sufficient stem cells for hematopoietic rescue after myeloablation, and more than one leukapheresis is necessary in most patients. We conceived the feasibility of harvesting sufficient numbers of hematopoietic cells from the whole blood, obtainable by venaepunctures, of patients treated with a standard dose chemotherapy regimen for high-grade non-Hodgkin's lymphoma. We evaluated the kinetics of mobilization, amount and quality of hematopoietic cells released into circulation during VACOB-B chemotherapy (which consists of a 12-week program), and G-CSF in 6 patients with aggressive non-Hodgkin's lymphoma. The median number of granulocyte-macrophage colony-forming cells (GM-CFC) x 10(3)/ml of blood (range), were 1.9 (0.3-8), and 1.16 (0.2-3.2) after the 7th and 11th weekly dose of drugs, respectively, showing an increase of 19- and 12-fold over patients' prechemotherapy values and of 53- and 33-fold over normal controls (p < 0.001). The median number of CD34+ cells x 10(3)/ml of blood (range), at the 7th and 11th cycle, was 135 (53.7-240.9) and 79.8 (69-173.5), respectively, showing an increase of 10- and 13-fold over patients prechemotherapy values (p < or = 0.04) and of 300- and 179-fold over normal controls (p < or = 0.001). Long-term culture initiating cells (LTC-IC) were released into circulation together with hematopoietic progenitors. We estimated that 1 liter of peripheral blood could yield on average 1.8 x 10(6)/kg CD34+ cells and 2 x 10(4)/kg GM-CFC with LTC-IC frequency comparable to a bone marrow harvest. These figures may be considered sufficient for hematopoietic rescue after myeloablation or hematopoietic support after high-dose chemotherapy.

Antibodies binding granulocyte-macrophage colony stimulating factor produced by cord blood-derived B cell lines immortalized by Epstein-Barr virus in vitro.

We detected natural antibodies (auto-Abs) binding human granulocyte-macrophage colony stimulating factor (GM-CSF) in umbilical cord blood (CB) (23 of 94 samples screened) and peripheral blood of women at the end of pregnancy (6 of 42 samples tested). To demonstrate that Abs detected in CB were produced by the fetus, CB mononuclear cells were infected with Epstein-Barr virus in vitro. Ten cell lines producing constitutively anti-recombinant human GM-CSF (rhGM-CSF) Abs were isolated and characterized. These cells displayed a male karyotype, an early activated B cell phenotype, coexpressed surface IgM and IgD, and secreted only IgM with prevailing lambda clonal restriction. Specific cell surface binding of biotinylated rhGM-CSF and high-level anti-rhGM-CSF IgM Ab production were typical features of early cell cultures. In late cell passages the frequency of more undifferentiated B cells increased. Serum Abs of either maternal or fetal origin or Abs produced in culture did not affect the granulocyte and macrophage colony stimulating activity of rhGM-CSF from bone marrow progenitors in soft agar, suggesting that the Abs produced were nonneutralizing.

B7 costimulatory molecules from malignant cells in patients with b-cell chronic lymphoproliferative disorders trigger t-cell proliferation.

BACKGROUND: B7 family molecules are involved in T-B-cell communications after interaction with their ligands CD28 and CD152. They play a key role in costimulatory mechanisms and during antigen presentation by efficient antigen presenting cells. B7 molecules are usually absent or expressed at low intensity on B lymphocytes from healthy subjects. In this study, the authors addressed the questions of whether B7 molecules are expressed and modulated in vitro on malignant B lymphocytes from patients with chronic lymphoproliferative diseases of B-cell type and whether they are able to trigger allogenic T-cell reactions. METHODS: Malignant B cells from the peripheral blood of 32 patients with B-cell chronic lymphocytic leukemia, mantle cell lymphoma, hairy cell leukemia, and its variant form were investigated for the expression of B7 molecules on the cell surface and for the ability to trigger allogenic T lymphocytes in different experimental conditions. RESULTS: Flow cytometry analysis demonstrated that freshly isolated malignant B cells express B7 molecules and that their expression may be up-regulated by the in vitro triggering of the CD40 molecule. Furthermore, freshly isolated malignant B cells induce allogenic T-cell proliferation. The in vitro triggering of malignant B lymphocytes by CD40, alone and in combination with interleukin-4, elicits a strong allogenic T-cell proliferation. This T-cell proliferation is related mainly to the presence of B7 molecules on malignant and normal B lymphocytes. CONCLUSIONS: These findings indicate that malignant B cells are efficient antigen presenting cells. It might be suggested that vaccination with pulsed malignant B cells themselves or dendritic cells with in vitro preactivated tumor B cells may represent an alternative therapeutic approach in these patients to generate an antilymphoma T-cell response in vivo.

Intracellular cytokine profile of cord blood T-, and NK- cells and monocytes.

BACKGROUND AND OBJECTIVES: Many functional peculiarities of cord blood (CB) lymphocytes and antigen presenting cells, including cytokine production, are associated with low intensity of innate and acquired (cellular and humoral) responses. These peculiarities may have implications both for immunologic maturation in post-natal life and for immune functions after CB transplantation [e.g. the lower incidence of graft-versus-host disease (GvHD) in comparison with after bone marrow transplantation (BMT)]. The aim of our study was to compare the intracellular production of cytokines involved both in phagocyte-dependent immunity/inflammation and in humoral immune responses in CB and adult peripheral blood (PB). DESIGN AND METHODS: Intracellular single cell analysis by flow cytometry was used to detect, following aspecific in vitro stimulation, the production of interferon (IFN)-gamma, Interleukin (IL)-2, IL-1alpha, IL-1beta, IL-8, tumor necrosis factor (TNF)-alpha and -beta, IL-4, IL-5, IL-6, IL-10 and IL-13 by T-cell subsets, NK-cells and monocytes obtained from 10 CB and 10 PB samples. The cytokine production was expressed as the percentage of positive cells. RESULTS: Significantly lower number of CD4+ T-cells producing IFN-g (p<0.001), TNF-alpha (p=0.012) and TNF-beta (p=0.03) and of CD8+ T-cells producing IFN-gamma (p<0.001), IL-2 (p=0.005) and TNF-alpha (p<0.001) were found in CB as compared to PB. In CB we have also found a lower number of NK cells and monocytes producing TNF-alpha (p<0.001 and p=0.001, respectively). In contrast, the number of IL-1alpha+ monocytes was higher in CB than in PB (p=0.03). INTERPRETATION AND CONCLUSIONS: Our data confirm that the cytokines which normally sustain the phagocytic-dependent T helper/cytotoxic 1-type immune responses (IFN-gamma, IL-2 and TNF-alpha) and the NK cell/monocyte-dependent aspecific responses (TNF-alpha) are reduced in CB. Since these cytokines are also involved in acute GvHD pathogenesis, these results are in keeping with the evidence of a low incidence of acute GvHD after CB transplantation.

Increased proteasome degradation of cyclin-dependent kinase inhibitor p27 is associated with a decreased overall survival in mantle cell lymphoma.

Mantle cell lymphoma (MCL) is an aggressive neoplasm characterized by the deregulated expression of cyclin D1 by t(11;14). The molecular mechanisms responsible for MCL's clinical behavior remain unclear. The authors have investigated the expression of p53, E2F-1, and the CDK inhibitors p27 and p21 in 110 MCLs, relating their expression to proliferative activity (Ki-67). For comparison, they have similarly analyzed low-grade (12 MALT, 16 CLL/SLL) and high-grade (19 DLCL) lymphomas. p53 was detected more frequently in large-cell MCL (l-MCL; 5 of 7) than in classical MCL (s-MCL; 13 of 103) and DLCL (8 of 19). In MCL and DLCL, the percentage of E2F-1+ nuclei was high, correlating with high Ki-67 expression. Most MCLs (91 of 112) and DLCLs (12 of 19) showed a loss of p27; MALT and CLL/SLL, however, were p27 positive. Reverse transcription-polymerase chain reaction and in vitro protein degradation assays demonstrated that MCLs have normal p27 mRNA expression but increased p27 protein degradation activity via the proteasome pathway. Correlation of MCL p53 and p27 expression with clinical data showed an association between reduced overall survival rates and the overexpression of p53 (P =.001), the loss of p27 (P =. 002), or both. Loss of p27 identified patients with a worse clinical outcome among p53 negative cases (P =.002). These findings demonstrated that MCL has a distinct cell cycle protein expression similar to that of high-grade lymphoma. The loss of p27 and the overexpression of p53 in MCL are prognostic markers that identify patients at high risk. The demonstration that low levels of p27 in MCL result from enhanced proteasome-mediated degradation should encourage additional clinical trials. (Blood. 2000;95:619-626) (Blood. 2000;95:619-626)