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The posttransplant lymphoproliferative disorders (PTLDs) are a heterogeneous group of neoplasms that have wide variety of clinical and histological presentations. The management of PTLDs is challenging due to variety of involvement sites and histological types. The length and type of immunosuppression are correlated with the emergence of PTLDs, and most of the cases appear within the first two years after transplant. This case series describes five late-onset PTLDs with rare histological features and multiorgan involvement.

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Utilizing a clinically relevant haploidentical (HI) murine transplant model, lethally irradiated B6D2F1 (H2K(b/d)) mice were transplanted with T cell-depleted (TCD) BM from B6CBAF1 (H2K(b/k)) mice. We found that administration of IL-15 significantly increases the numbers of CD8+ T and natural killer (NK) cells in spleen and BM after transplantion without GVHD. Graft-versus-tumor (GVT) potency of the graft was evaluated upon tumor challenge using P815 tumor cells (H2(d)). IL-15 administration without T-cell infusion did not result in any survival improvement. However, IL-15 in combination with very low-dose T-cell infusion (1 × 10(4)) significantly increased GVT activity and improved survival in recipients of HI hematopoietic SCT (HSCT). This effect was observed when IL-15 was given at a later time point, rather than immediately following transplantation. IL-15 administration also specifically increased slow-proliferative CD8+ T-cell proliferation and IFN-γ secretion in CD8+ T cells in recipients of CFSE (carboxyfluorescein succinimidyl ester)-labeled HI T-cell infusion, whereas there was no effect on CD4+ T-cell proliferation, suggesting the critical effect of IL-15 on CD8+ T-cell homeostasis in HI host. We conclude that IL-15 can be used for enhancing antileukemia effect of HI-HSCT, which requires presence of donor-derived T cells.

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Allogeneic hematopoietic SCT (HSCT) has been shown to be an effective treatment option for advanced renal cell cancer (RCC). However, tumor resistance/relapse remains as the main post transplant issue. Therefore, enhancing graft-versus-tumor (GVT) activity without increasing GVHD is critical for improving the outcome of HSCT. We explored the GVT effect of haploidentical-SCT (haplo-SCT) against RCC in murine models. Lethally irradiated CB6F1 (H2K(b/d)) recipients were transplanted with T-cell-depleted BM cells from B6CBAF1 (H2K(b/k)) mice. Haplo-SCT combined with a low-dose haploidentical (HI) T-cell infusion (1 × 10(5)) successfully provided GVT activity without incurring GVHD. This effect elicited murine RCC growth control and consequently displayed a comparative survival advantage of haplo-SCT recipients when compared with MHC-matched (B6D2F1CB6F1) and parent-F1 (B6CB6F1) transplant recipients. Recipients of haplo-SCT had an increase in donor-derived splenic T-cell numbers, T-cell proliferation and IFN-γ-secreting donor-derived T-cells, a critical aspect for anti-tumor activity. The splenocytes from B6CBAF1 mice had a higher cytotoxicity against RENCA cells than the splenocytes from B6 and B6D2F1 donors after tumor challenge. These findings suggest that haplo-SCT might be an innovative immunotherapeutic platform for solid tumors, particularly for renal cell carcinoma.

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Umbilical cord blood (UCB) is a readily available source of hematopoietic stem cells for transplantation. UCB hematopoietic SCT for average- and large-sized patients is often limited by the number of cells available in a single unit. To address this limitation, we performed experiments to determine if adjunctive therapy with third-party human allogeneic cells enhances the engraftment of human UCB in immunodeficient mice. UCB cells with or without sequential infusion of irradiated third-party allogeneic cells were used in transplantation studies of NOD/SCID and NOD/SCID-IL2Rγ null mice. We studied the impact of irradiated allogeneic cells on colony formation in vitro using long-term culture assays also. Our studies demonstrate that short- and long-term UCB engraftment of immunodeficient mice is enhanced by irradiated allogeneic cells. Secondary transplants demonstrate the durability of engraftment. These preclinical studies support the further development of irradiated allogeneic cells as an adjunct to single UCB transplantation when limiting numbers of cells are available.

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In general, tuberculosis (Tb) is rarely seen in allogeneic stem cell transplant (alloSCT) recipients, but this observation has been challenged in developing countries such as Turkey, where Tb infection is more prevalent than in Europe and the US. In this retrospective study, we report on the incidence of Tb infections in 351 alloSCT recipients at 4 bone marrow transplantation units in Turkey over the last 10 years. The frequency of Tb in alloSCT recipients after allografting (5 of 351) was far greater than that in the general population (35.4 per 100,000). Of the 351 patients who underwent alloSCT, 77 who received isoniazid (INH) chemoprophylaxis for 6 months did not develop posttransplantation Tb. However, 5 of the remaining 274 patients who received no chemoprophylaxis developed Tb a median of 12 months (range, 10-47 months) after allografting. Antituberculosis therapy resulted in complete recovery in all cases. In 2 additional patients who were found to have active pulmonary Tb at the time of transplantation, alloSCT was delayed until the infections were treated. Infections of mycobacteria other than Mycobacterium tuberculosis were not observed. The number of patients who received and tolerated INH may not be sufficient for firm conclusions, but the data suggest that, in countries where Tb is prevalent, pre- and posttransplantation follow-up for Tb and the use of INH prophylaxis should be considered.

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Chronic a-interferon use has been reported to cause a variety of neurotoxic side effects. This case summary suggests the possibility of a new neurotoxic side effect of normal pressure hydrocephalus following chronic a-interferon use.

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Clonogenic capacity of bone marrow progenitors and stromal layers established from bone marrow of 12 patients with CML and 13 healthy controls were evaluated. The initial BFU-E and CFU-GM contents were slightly higher in the CML patients (p > 0.05) in contrast to CFU-GEMM. CFU-GEMM was lower in the patients compared to healthy controls (p < 0.001). In long-term cultures, the number of non-adherent cell population and total clonogenic progenitor cell content decreased gradually in both groups. Weekly evaluation of stromal confluency of adherent cells revealed that establishment of adherent stromal layer was slower in CML patients than in control samples (p < 0.05). At the end of fourth week, the number of samples presenting confluency was 41.7% in the CML group compared with 92.3% in the controls. The initial CD34 positive cell content of the bone marrow samples was similar in both groups. Although CD34 positive cell number in the adherent stromal layer was well preserved in the control group at the end of 4 weeks, this figure decreased significantly in the CML group. The numbers of total adherent cells as well as the total clonogenic progenitor content of adherent layer were also lower in the CML group (3.03% vs 98.2%). When normal CD34+ cells were cultured on IFN-alpha-treated stromal layer followed by the assessment of the long-term culture initiating cells, a reduced capacity to support hemopoietic growth was observed with IFN-alpha-treated normal stroma. This reduction was even higher when CML stroma was treated with IFN-alpha followed by the seeding of the normal CD34+ cells on this stromal layer (26.9% vs 42.8%). These findings show that stromal cells are abnormal in CML patients as well as the progenitor cells, and IFN-alpha treatment causes further defects of the stromal cells.

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In order to investigate the relationship between aberrant marker expression and DNA ploidy, 61 adult patients with acute leukemia (39 AML and 22 ALL) were studied. Aberrant marker expression was observed in 20 patients (16/39 of AML and 4/22 of ALL patients). In flow cytometric DNA analysis aneuploidy was observed in 18 patients (9/39 of AML and 9/22 of ALL patients). The incidence of aneuploidy in patients with aberrant marker expression was 35% whereas this was 26.8% in patients without aberrant marker expression. Furthermore, 7 patients with aberrant marker expression showed an aneuploid, double G0/G1 peaks appearance whereas the remaining 11 patients with aberrant marker expression had euploid DNA content. Double G0/G1 appearance was not observed in patients without aberrant marker expression. Further analyses revealed that this did not correlate with apoptosis. All 7 patients, who had both aberrant marker expression and double G0/G1 peak had a poor clinical outcome with a short survival and all died within three months whereas three-months survival was 67% for AML, 69% for ALL patients and 81% for patients with aberrant marker expression respectively (p<0.01). Our data indicate that the evaluation of the DNA ploidy in patients with aberrant marker expression may be of prognostic importance.

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Typical manifestations of Behcet's disease (BD) and a positive pathergy reaction were observed in a few patients with chronic myeloid leukaemia (CML) on interferon alpha (IFN-alpha) therapy and the significance of this observation was assessed in a prospective study. The skin pathergy test was applied to 15 patients with CML prior to IFN-alpha therapy, 29 patients with CML following IFN-alpha therapy and 30 patients with BD. Twenty-five patients with inflammatory arthropathies (IA), 20 patients with recurrent oral ulcers (ROU), 23 patients treated with IFN-alpha for various disorders and 20 normal individuals were also studied as control groups. The pathergy reaction was positive in nearly a quarter of IFN-alpha-treated CML cases (24%) as well as one-half of the patients with BD (50%). All CML patients prior to IFN-alpha treatment and all patients using IFN-alpha for other diseases were negative for the pathergy reaction. These results may indicate a similarly altered neutrophil function in both BD and IFN-alpha-treated CML patients.

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Fifty-seven adult patients with idiopathic thrombocytopenic purpura (ITP) were treated with either conventional-dose prednisolone (CDP) (1 mg/kg/d, 36 patients) or high-dose methylprednisolone (HDP) (30 mg/kg/d, 21 patients), as first-line treatment. Patients in the HDP arm responded more rapidly (4.7 v 8.4 d), with a higher response rate (80% v 52.7%), and without severe side-effects. One quarter of the patients (3/12) who were non-responsive to CDP achieved complete remission when they were treated with HDP. The findings suggest that HDP may be a more effective first-line treatment than CDP for adult ITP, and it may also be preferred for life-threatening cases of ITP. However, these results must be confirmed by a randomized study prior to any change in the current practice of employing CDP as first-line treatment for adult ITP.

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Two patients with chronic myelogenous leukemia (CML) who developed characteristic features of Behçet's disease (BD) during alpha-interferon (IFN-alpha) treatment and another patient who had a diagnosis of BD preceding CML are presented. In the first two patients, features of BD appeared 6 months after the initiation of IFN-alpha treatment: they included recurrent oral aphthae, genital ulceration, arthritis, folliculitis, and a positive skin pathergy test. The third patient, however, had a diagnosis of Behçet's disease 4 years before diagnosis of Philadelphia-positive CML. We prospectively examined the skin pathergy reaction in a group of patients with CML, multiple myeloma, and hairy cell leukemia both before and after IFN-alpha treatment and found two additional patients with CML who developed a positive skin pathergy test following IFN-alpha treatment.

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