Mesenchymal stromal cells (MSCs) have unique characteristics such immune suppression by inhibiting T cell proliferation, tissue-repair ability and acceleration of hemopoietic stem cell engraftment. The cells are rare in bone marrow, but easily cultured under standard culture conditions. Soluble factors and cells are implicated in the MSC-mediated T cell suppression and numerous clinical trials using MSCs to prevent and treat graft-versus-host disease (GVHD) have been reported. MSCs are suggested to suppress acute GVHD without impairing graft-versus-leukemia effects and increasing systemic infections. In this review, we focus on basic aspects of MSC-mediated T cell suppression and clinical trials using MSCs for GVHD and related conditions.

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Rearrangements of the MLL gene located at 11q23 are common chromosomal abnormalities associated with acute leukemia (AL), especially infant and secondary leukemia after previous treatment with DNA topoisomerase II inhibitors. 11q23/MLL abnormalities have been widely recognized as an important prognostic factor in AL. Over 70 chromosome partners of 11q23 have been identified to date, at least 50 of which have been cloned and characterized at the molecular level. Recent studies showed that the prognosis of 11q23/MLL AL varies widely according to the partner gene, the leukemia cell lineage, the age of the patient and the treatment administered. Special strategies are needed to treat 11q23/MLL AL, including allogeneic hematopoietic stem cell transplantation, according to the fusion partner. The development of novel methodologies, including new molecular therapeutic targets, is also needed to improve the prognosis of 11q23/MLL AL. The present article provides an update on the current status of prognosis and treatment of 11q23/MLL AL according to the fusion partner.

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We investigated the priming effect and mechanism of granulocyte colony-stimulating factor (G-CSF) in chemotherapy with low-dose Ara-C and VP-16 for acute myeloid leukemia. We analyzed cell proliferation, apoptosis, and cell cycle in vitro using leukemia cell lines 32Dcl3, U937, HL-60, and Ba/F3. Cell proliferation assays were performed using the Trypan Blue dye exclusion method. For detection of apoptosis, the Annexin V-binding capacity of treated cells was examined by flow cytometry. To evaluate the cell cycle, we used an FITC BrdU Flow kit and conducted analysis by flow cytometry. The combination of Ara-C and VP-16 significantly enhanced the observed effects compared with those of Ara-C or VP-16 alone. Concurrent administration of G-CSF further reduced the cell number and viability of 32Dcl3 and U937 cells, but not of HL-60 and Ba/F3 cells. Apoptotic cells were significantly increased in number by the addition of G-CSF to 32Dcl3 and U937 cells, while G-CSF had no significant effect on HL-60 and Ba/F3 cell lines. The addition of G-CSF significantly decreased the percentage of G0/G1-phase cells and significantly increased that of S-phase cells among 32Dcl3 and U937 cells. No significant effect was observed for HL-60 and Ba/F3 cells. An enhancement was confirmed for the combination of Ara-C, VP-16, and G-CSF for 32Dcl3 and U937 cells but not for HL-60 and Ba/F3 cells. It was thought that this difference was a result of different responses to G-CSF. G-CSF potentiates Ara-C- and VP-16-induced cytotoxicities through apoptosis induction by mobilizing resting G0-G1-phase cells into S phase.

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Splenic marginal zone lymphoma (SP-MZL) is a rare low-grade B-cell neoplasm that often shows leukemic manifestation. Less than 20% of cases of SP-MZL express CD5. We analyzed 11 cases of CD5-positive SP-MZL with leukemic manifestation. The clinical characteristics of these cases did not differ from those of CD5-negative SP-MZL. Flow cytometry revealed positive results as follows : CD3, 0/9 ; CD5, 11/11 ; CD10, 0/11 ; CD11c, 4/10, CD13, 5/11 ; CD19, 11/11 ; CD20, 10/11 ; CD21, 4/4 ; CD22, 7/7 ; CD23, 5/10 ; CD25, 8/11 ; FMC7, 5/7 ; κ type 6/9, and λ type 2/9. All 3 cases with monoclonal γ-globulinemia expressed CD13. Resected spleen exhibited a proliferation of neoplastic cells in white pulp in all 8 splenectomy patients and a marginal pattern was detected in 5 patients. Only 2 cases showed involvement of red pulp. Immunohistochemistry showed that the lymphoma cells were positive for CD5, CD20, and BCL-2 and negative for CD3, CD10, cyclin D1, BCL-6, and MUM-1 in all 11 cases. These results suggest that CD5-positive SP-MZL differs from B-cell chronic lymphocytic leukemia, that CD13 expression is found in about half of CD5-positive SP-MZL cases, and that CD5-positive SP-MZL may be related to memory B-cell neoplasm or plasma cell differentiation.

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Atypical lymphoplasmacytic immunoblastic proliferation (ALPIB) is a rare lymphoproliferative disorder (LPD) associated with autoimmune disease (AID). To further clarify the clinicopathologic, immunohistological, and genotypic findings of ALPIB in lymph nodes associated with well-documented AIDs, 9 cases are presented. These 9 patients consisted of 4 patients with systemic lupus erythematosus, 3 patients with rheumatoid arthritis, and one case each with Sjögren's syndrome and dermatomyositis. All 9 patients were females aged from 25 to 71 years with a median age of 49 years. Four cases presented with lymphadenopathy as the initial manifestation. In 4 patients, immunosuppressive drugs were administered before the onset of lymph node lesion. However, none of the 9 patients received methotrexate therapy. The present 9 cases were characterized by : (i) prominent lymphoplasmacytic and B-immunoblastic infiltration ; (ii) absence of pronounced arborizing vascular proliferation ; (iii) absence of CD10⁺ “clear cells” ; (iv) presence of hyperplastic germinal center in 7 cases ; (v) immunohistochemistry, flow cytometry, and polymerase chain reaction demonstrated a reactive nature of the T- and B-lymphocytes ; and (vi) on in situ hybridization, there were no Epstein-Barr virus -infected lymphoid cells in any of the 9 cases. Overall 5-year survival of our patients was 83%. The combination of clinical, immunophenotypic, and genotypic findings indicated that the present 9 cases can be regarded as having an essentially benign reactive process. Finally, we emphasized that ALPIB should be added to the differential diagnostic problems of atypical LPDs, particularly lymph node lesions of IgG4-related diseases.

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B-cell activating factor receptor (BAFF-R) is one of three known receptors for BAFF. BAFF-R is required for B-cell maturation and survival. We tried to determine the normal pattern of BAFF-R expression in non-neoplastic and neoplastic B- and T-cells. We used immunohistochemistry to evaluate the expression pattern of BAFF-R in non-neoplastic and neoplastic lymphoid tissues of routinely fixed paraffin-embedded samples, and examined the relationships among BAFF-R and expressions of CD10, bcl-6, MUM-1, and MIB-1. BAFF-R expression was detected on B-cells of the mantle zones, some cells within germinal centers, and scattered cells in the interfollicular areas of reactive lymph nodes. BAFF-R expression was only found in B-cell lymphoma (60/120, positive samples/examined samples), but not in T/NK cell lymphoma (0/10) or Hodgkin lymphoma (0/10). The proportions were as follows : follicular lymphoma (14/16), diffuse large B-cell lymphoma (DLBCL) (27/61), mantle cell lymphoma (4/4), and Burkitt lymphoma (0/4). According to Hans' criteria, DLBCLs were subclassified into germinal center B-cell-like (GCB) and non-germinal center B-cell-like (non-GCB) types. Interestingly, in nodal lymphomas, in the GCB subgroup (n=12), 9 of 12 (75%) were positive for BAFF-R, while 6 of 20 (30%) were positive in the non-GCB subgroup (n=20) (p < 0.05). In addition, expression of BAFF-R related to lower MIB-1 index was associated with GCB-type DLBCL. In conclusion, BAFF-R was only found in some B-cell lymphomas, which was closely associated with the expression pattern in normal counterparts, although BAFF-R expression on follicular lymphoma is different from that on germinal center cells, which is similar to bcl-2. BAFF-R was rather specifically related to low growth activity of GCB-type DLBCL of nodal origin.

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The purpose of this study is to determine the relationship of ocular adnexal benign or reactive lymphoid hyperplasia, including orbital pseudotumor, with immunoglobulin G4 (IgG4)-related diseases. Medical charts of 9 consecutive patients with ocular adnexal benign lymphoid lesions, seen in the Department of Ophthalmology, Okayama University Hospital, were reviewed, and pathological sections were restained immunohistochemically for IgG4-, IgG-, and CD138-positive plasma cells. The diagnosis of IgG4-positive lesions was based on 10 or more IgG4-positive plasma cells in a high-power field and greater than 40% ratios of IgG4-positive plasma cells/CD138-positive plasma cells and IgG4-positive plasma cells/IgG-positive plasma cells. IgG4-positive lesions were determined as absent in 5 patients (4 with bilateral lacrimal/orbital lesions and one with a unilateral conjunctival lesion), none of whom showed systemic manifestations. In contrast, IgG4-positive lesions were present in 4 patients (3 with bilateral lacrimal/orbital lesions and one with a unilateral lacrimal/orbital lesion), who showed systemic manifestations : one with Hashimoto thyroiditis, one with IgG4-positive bilateral interstitial lung disease and hepatic inflammatory pseudotumor, one with bilateral interstitial lung disease, and one with systemic lymphadenopathy and antiphospholipid syndrome. In conclusion, IgG4-positive ocular adnexal benign lymphoid lesions might be used as a benchmark for the probable presence of other systemic lymphoid lesions.

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Mediastinal gray zone lymphoma (MGZL) represents a range of tumors possessing characteristics of both nodular sclerosis classical Hodgkin lymphoma (NSHL) and mediastinal large B-cell lymphoma (MLBCL). Here we report two patients with MGZL. Patient 1 was a 30-year-old woman and patient 2 was a 22-year-old man. Both patients had a mediastinal mass, were initially diagnosed with NSHL and exhibited resistance to first-line chemotherapy. Re-biopsy of the relapsed tumors or the residual lesion was performed and based on the findings the tumors were diagnosed as MGZL. In patient 1, the morphological features of the tumor resembled those of NSHL, but the immunophenotypic features indicated MLBCL. In patient 2, the tumor was a composite lymphoma with both NSHL and MLBCL components. Both the patients received high-dose chemotherapy followed by autologous peripheral-blood stem-cell transplantation. Although there is an overlap in the biological and morphological features between NSHL and MLBCL, the therapeutic approaches to NSHL and MLBCL are quite different. The development of effective therapies for MGZL is therefore extremely critical.

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We report a case of primary pulmonary classical Hodgkin lymphoma (CHL) in a 58-year-old woman. Twelve years ago, the patient complained of slight fever and weight loss. A mass of about 5 cm in diameter was seen in the right lung on radiography and computed tomography (CT). Right total pneumonectomy and resection of mediastinal lymph nodes were performed. A pathological examination led to a strong suspicion of Hodgkin disease (HD) (now referred to as CHL), but a definite diagnosis could not be made at the time. Six years later, a chest CT showed a tumor around the ascending aorta, which was treated successfully by radiation therapy. Six years later, the chest CT revealed a tumor in the anterior mediastinum. CHL was diagnosed based on an immunohistochemical re-examination of lung specimens resected 12 years earlier and CT-guided fine needle tumor biopsy specimens of the second recurrent tumor in the anterior mediastinum were compatible with the recurrence of CHL. Therefore, we diagnosed this case as primary pulmonary CHL that later relapsed in the mediastinum. The tumor size was reduced by radiation therapy and the patient is currently under observation as an outpatient.

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We report two cases of Pneumocystis jiroveci pneumonia (PCP) with CD20⁺ B-cell lymphoma. They were treated by several courses of CHOP-based chemotherapy containing rituximab. We confirmed by flow cytometric analysis that both of them completely lost CD19⁺ and CD20⁺ B-cells from their peripheral blood after the first course of chemotherapy. They were successfully treated with Trimethoprim-sulfamethoxazole (TMP-SMX) after the diagnosis of PCP by polymerase chain reaction (PCR). We overviewed CD20⁺ B-cell lymphoma patients treated with CHOP-based regimens from 1997 until 2005 in our hospital. We treated 114 patients with and 121 patients without rituximab. Five patients in the group with rituximab developed interstitial pneumonia (IP). Two of them were confirmed to have PCP and the other three were suspected cases ; however, no patients with IP were seen in the group without rituximab. We strongly suggest the necessity of PCP prophylaxis with oral TMP-SMX when treating B-cell lymphoma patients with chemotherapy containing rituximab.

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A 70-year-old female with a long history of progressive leukocytopenia and giant splenomegaly is described. She had no clinically manifested rheumatoid arthritis, although she complained of slight arthralgia in the digital joints, wrists and ankles at irregular intervals. Repeated bone marrow aspirations showed no cellular atypism, chromosomal abnormalities, or phenotypical abnormalities. Just before splenectomy, both anti-neutrophil antibody positivity and anti-cyclic citrullinated peptide antibody positivity were shown. Histology of the splenectomized spleen showed follicular hyperplasia with plasmacyte infiltration and extramedullary hematopoeisis. After splenectomy, leukocyte counts returned to normal with normal leukocyte differentials and anti-neutrophil antibodies disappeared. She was almost free of arthralgia one year after splenectomy, although the anti-cyclic citrullinated peptide antibody titers remained high.

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