Primary plasma cell leukaemia

Plasma cell leukemia (PCL) is a rare form of malignant plasma cell dyscrasia. It can occur as a primary form without prior evidence of multiple myeloma or as a secondary form which is a terminal event in multiple myeloma. It is characterised by a proliferation of plasma cells in blood and the bone marrow. The outcome of plasma cell leukemia is poor with conventional therapy. Here we illustrate a case of primary plasma cell leukemia complicated by paraplegia. The patient initially responded to combination chemotherapy but succumbed to the disease two months after presentation

Extreme Peripheral Blood Plasmacytosis Mimicking Plasma Cell Leukemia as a Presenting Feature of Angioimmunoblastic T-Cell Lymphoma (AITL).

Angioimmunoblastic T-cell lymphoma (AITL) is one of four major subtypes of nodal peripheral T cell lymphoma, characterized by its cell of origin, the follicular helper T-cell (TFH). Patients typically present with prominent constitutional (B) symptoms, generalized lymphadenopathy, hepatosplenomegaly, cytopenias, and rash. Here we present a case of a 62-year-old male with progressive cervical adenopathy, fevers and weight loss presenting with extreme polyclonal plasmacytosis and high plasma EBV viral load. While the initial presentation appeared to mimic plasma cell leukemia or severe infection, lymph node biopsy and bone marrow biopsy confirmed a diagnosis of AITL. This case highlights the heterogeneity of the clinical presentation of AITL to enable physicians to more promptly recognize, diagnose and initiate treatment

Gender effects on cytidine analogue metabolism and myelodysplastic syndrome treatment outcomes

In vivo, half-lives of cytidine analogues such as 5-azacytidine and decitabine, used to treat myelodysplastic syndromes (MDS), are determined largely by cytidine deaminase (CDA), an enzyme that rapidly metabolizes these drugs into inactive uridine counterparts. Genetic factors influence CDA activity, and hence, could impact 5-azacytidine/decitabine levels and efficacy, a possibility requiring evaluation. Using an HPLC assay, plasma CDA activity was confirmed to be decreased in individuals with the CDA SNP A79C. More interestingly, there was an even larger decrease in females. Explaining the decrease in enzyme activity, liver CDA expression was significantly lower in female versus male mice. As expected, decitabine plasma levels, measured by mass-spectrometry, were significantly higher in females. In mathematical modeling, the detrimental effect of shortening half-life of S-phase specific therapy was amplified in low S-phase fraction disease (e.g., MDS). Accordingly, in multivariate analysis of MDS patients treated with 5-azacytidine/decitabine, overall survival was significantly worse in males

High fludarabine exposure and relationship with treatment-related mortality after nonmyeloablative hematopoietic cell transplantation.

Despite its common use in nonmyeloablative preparative regimens, the pharmacokinetics of fludarabine are poorly characterized in hematopoietic cell transplantation (HCT) recipients and exposure-response relationships remain undefined. The objective of this study was to evaluate the association between plasma F-ara-A exposure, the systemically circulating moiety of fludarabine, and engraftment, acute GVHD, TRM and OS after HCT. The preparative regimen consisted of CY 50 mg/kg/day i.v. day -6; plus fludarabine 30-40 mg/m²/day i.v. on days -6 to -2 and TBI 200 cGy on day -1. F-ara-A pharmacokinetics were carried out with the first dose of fludarabine in 87 adult patients. Median (range) F-ara-A area-under-the-curve (AUC((0-∞))) was 5.0 μg h/mL (2.0-11.0), clearance 15.3 L/h (6.2-36.6), C(min) 55 ng/mL (17-166) and concentration on day(zero) 16.0 ng/mL (0.1-144.1). Despite dose reductions, patients with renal insufficiency had higher F-ara-A exposures. There was strong association between high plasma concentrations of F-ara-A and increased risk of TRM and reduced OS. Patients with an AUC((0-∞)) greater than 6.5 μg h/mL had 4.56 greater risk of TRM and significantly lower OS. These data suggest that clinical strategies are needed to optimize dosing of fludarabine to prevent overexposure and toxicity in HCT

Noninfectious retrovirus particles drive the APOBEC3/Rfv3 dependent neutralizing antibody response.

Members of the APOBEC3 family of deoxycytidine deaminases counteract a broad range of retroviruses in vitro through an indirect mechanism that requires virion incorporation and inhibition of reverse transcription and/or hypermutation of minus strand transcripts in the next target cell. The selective advantage to the host of this indirect restriction mechanism remains unclear, but valuable insights may be gained by studying APOBEC3 function in vivo. Apobec3 was previously shown to encode Rfv3, a classical resistance gene that controls the recovery of mice from pathogenic Friend retrovirus (FV) infection by promoting a more potent neutralizing antibody (NAb) response. The underlying mechanism does not involve a direct effect of Apobec3 on B cell function. Here we show that while Apobec3 decreased titers of infectious virus during acute FV infection, plasma viral RNA loads were maintained, indicating substantial release of noninfectious particles in vivo. The lack of plasma virion infectivity was associated with a significant post-entry block during early reverse transcription rather than G-to-A hypermutation. The Apobec3-dependent NAb response correlated with IgG binding titers against native, but not detergent-lysed virions. These findings indicate that innate Apobec3 restriction promotes NAb responses by maintaining high concentrations of virions with native B cell epitopes, but in the context of low virion infectivity. Finally, Apobec3 restriction was found to be saturable in vivo, since increasing FV inoculum doses resulted in decreased Apobec3 inhibition. By analogy, maximizing the release of noninfectious particles by modulating APOBEC3 expression may improve humoral immunity against pathogenic human retroviral infections

Fatal lymphoproliferation and acute monocytic leukemia-like disease following infectious mononucleosis in the elderly

Three elderly patients are reported, in whom serologically confirmed recent infectious mononucleosis is followed by fatal lymphoproliferation (case 1), by acute monocytic leukemia (case 2), and by acute probably monocytic leukemia (case 3)

HTLV-1 Tax-1 interacts with SNX27 to regulate cellular localization of the HTLV-1 receptor molecule, GLUT1

An estimated 10–20 million people worldwide are infected with human T cell leukemia virus type 1 (HTLV-1), with endemic areas of infection in Japan, Australia, the Caribbean, and Africa. HTLV-1 is the causative agent of adult T cell leukemia (ATL) and HTLV-1 associated myopathy/tropic spastic paraparesis (HAM/TSP). HTLV-1 expresses several regulatory and accessory genes that function at different stages of the virus life cycle. The regulatory gene Tax-1 is required for efficient virus replication, as it drives transcription of viral gene products, and has also been demonstrated to play a key role in the pathogenesis of the virus. Several studies have identified a PDZ binding motif (PBM) at the carboxyl terminus of Tax-1 and demonstrated the importance of this domain for HTLV-1 induced cellular transformation. Using a mass spectrometry-based proteomics approach we identified sorting nexin 27 (SNX27) as a novel interacting partner of Tax-1. Further, we demonstrated that their interaction is mediated by the Tax-1 PBM and SNX27 PDZ domains. SNX27 has been shown to promote the plasma membrane localization of glucose transport 1 (GLUT1), one of the receptor molecules of the HTLV-1 virus, and the receptor molecule required for HTLV-1 fusion and entry. We postulated that Tax-1 alters GLUT1 localization via its interaction with SNX27. We demonstrate that over expression of Tax-1 in cells causes a reduction of GLUT1 on the plasma membrane. Furthermore, we show that knockdown of SNX27 results in increased virion release and decreased HTLV-1 infectivity. Collectively, we demonstrate the first known mechanism by which HTLV-1 regulates a receptor molecule post-infection.</div