Allogeneic haematopoietic cell transplantation for extranodal natural killer/Tâ cell lymphoma, nasal type: a CIBMTR analysis

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146342/1/bjh14879.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146342/2/bjh14879_am.pd

Immunophenotypic studies of monoclonal gammopathy of undetermined significance

<p>Abstract</p> <p>Background</p> <p>Monoclonal gammopathy of undetermined significance (MGUS) is a common plasma cell dyscrasia, comprising the most indolent form of monoclonal gammopathy. However, approximately 25% of MGUS cases ultimately progress to plasma cell myeloma (PCM) or related diseases. It is difficult to predict which subset of patients will transform. In this study, we examined the immunophenotypic differences of plasma cells in MGUS and PCM.</p> <p>Methods</p> <p>Bone marrow specimens from 32 MGUS patients and 32 PCM patients were analyzed by 4-color flow cytometry, using cluster analysis of ungated data, for the expression of several markers, including CD10, CD19, CD20, CD38, CD45, CD56 and surface and intracellular immunoglobulin light chains.</p> <p>Results</p> <p>All MGUS patients had two subpopulations of plasma cells, one with a "normal" phenotype [CD19(+), CD56(-), CD38(bright +)] and one with an aberrant phenotype [either CD19(-)/CD56(+) or CD19(-)/CD56(-)]. The normal subpopulation ranged from 4.4 to 86% (mean 27%) of total plasma cells. Only 20 of 32 PCM cases showed an identifiable normal subpopulation at significantly lower frequency [range 0–32%, mean 3.3%, p << 0.001]. The plasma cells in PCM were significantly less likely to express CD19 [1/32 (3.1%) vs. 13/29 (45%), p << 0.001] and more likely to express surface immunoglobulin [21/32 (66%) vs. 3/28 (11%), p << 0.001], compared to MGUS. Those expressing CD19 did so at a significantly lower level than in MGUS, with no overlap in mean fluorescence intensities [174 ± 25 vs. 430 ± 34, p << 0.001]. There were no significant differences in CD56 expression [23/32 (72%) vs. 18/29 (62%), p = 0.29], CD45 expression [15/32 (47%) vs. 20/30 (67%), p = 0.10] or CD38 mean fluorescence intensities [6552 ± 451 vs. 6365 ± 420, p = 0.38]. Two of the six MGUS cases (33%) with >90% CD19(-) plasma cells showed progression of disease, whereas none of the cases with >10% CD19(+) plasma cells evolved to PCM.</p> <p>Conclusion</p> <p>MGUS cases with potential for disease progression appeared to lack CD19 expression on >90% of their plasma cells, displaying an immunophenotypic profile similar to PCM plasma cells. A higher relative proportion of CD19(+) plasma cells in MGUS may be associated with a lower potential for disease progression.</p

Biochemical studies of human methionine synthase reductase

Methionine synthase is one of the major enzymes that metabolizes homocysteine and catalyzes the transfer of a methyl group from the substrate, methyltetrahydrofolate to the cobalamin cofactor and subsequently, to the second substrate, homocysteine to form methionine. Its cofactor, methylcobalamin, cycles between different oxidation states in the catalytic cycle and is prone to oxidative inactivation. The dual flavoenzyme, methionine synthase reductase (MSR), transfers electrons from NADPH to the cobalamin cofactor and, in conjunction with S-adenosylmethionine, reactivates mammalian methionine synthase. The physiological importance of this reaction is in freeing methyltetrahydrofolate from the tetrahydrofolate pool to support DNA synthesis. The clinical significance of the methionine synthase-catalyzed reaction stems from hyperhomocysteinemia, representing a risk factor in the multifactorial etiology of cardiovascular diseases. While hereditary hyperhomocysteinemia is characterized by plasma homocysteine levels surging up to 100–200 μM, the levels in mild hyperhomocysteinemia generally varies between 15–40 μM. A detailed understanding of the regulation of homocysteine metabolism is of substantial biomedical interest. With this in mind, we embarked on unraveling the biochemical function and properties of human MSR, which had been previously described only at a genetic level. The objective was to evaluate the role of MSR in methionine synthase activation which had been previously suggested by genetic studies. We successfully expressed recombinant human MSR and characterized its spectral, kinetic and electron transfer properties. Importantly, we demonstrated for the first time, that MSR is able to activate methionine synthase in the presence of NADPH and S-adenosylmethionine. We have also subjected two common variants of MSR, I22M and S175L to similar biochemical scrutiny. The I22M polymorphism has been linked to hyperhomocysteinemia and homocysteine-related diseases, in conjunction with other genetic and nutritional factors. From a comparison of (i) the UV-visible and EPR spectroscopic properties, (ii) the electron transfer reaction to the natural and to artificial electron acceptors, and (iii) the redox midpoint potentials of the flavin cofactors of the MSR polymorphic variants with the wild-type enzyme, we have postulated that the polymorphisms result in decreased efficiency between the redox partners during methionine synthase activation

Biochemical studies of human methionine synthase reductase

Methionine synthase is one of the major enzymes that metabolizes homocysteine and catalyzes the transfer of a methyl group from the substrate, methyltetrahydrofolate to the cobalamin cofactor and subsequently, to the second substrate, homocysteine to form methionine. Its cofactor, methylcobalamin, cycles between different oxidation states in the catalytic cycle and is prone to oxidative inactivation. The dual flavoenzyme, methionine synthase reductase (MSR), transfers electrons from NADPH to the cobalamin cofactor and, in conjunction with S-adenosylmethionine, reactivates mammalian methionine synthase. The physiological importance of this reaction is in freeing methyltetrahydrofolate from the tetrahydrofolate pool to support DNA synthesis. The clinical significance of the methionine synthase-catalyzed reaction stems from hyperhomocysteinemia, representing a risk factor in the multifactorial etiology of cardiovascular diseases. While hereditary hyperhomocysteinemia is characterized by plasma homocysteine levels surging up to 100–200 μM, the levels in mild hyperhomocysteinemia generally varies between 15–40 μM. A detailed understanding of the regulation of homocysteine metabolism is of substantial biomedical interest. With this in mind, we embarked on unraveling the biochemical function and properties of human MSR, which had been previously described only at a genetic level. The objective was to evaluate the role of MSR in methionine synthase activation which had been previously suggested by genetic studies. We successfully expressed recombinant human MSR and characterized its spectral, kinetic and electron transfer properties. Importantly, we demonstrated for the first time, that MSR is able to activate methionine synthase in the presence of NADPH and S-adenosylmethionine. We have also subjected two common variants of MSR, I22M and S175L to similar biochemical scrutiny. The I22M polymorphism has been linked to hyperhomocysteinemia and homocysteine-related diseases, in conjunction with other genetic and nutritional factors. From a comparison of (i) the UV-visible and EPR spectroscopic properties, (ii) the electron transfer reaction to the natural and to artificial electron acceptors, and (iii) the redox midpoint potentials of the flavin cofactors of the MSR polymorphic variants with the wild-type enzyme, we have postulated that the polymorphisms result in decreased efficiency between the redox partners during methionine synthase activation

Emerging Role of T-cell Receptor Constant β Chain-1 (TRBC1) Expression in the Flow Cytometric Diagnosis of T-cell Malignancies

T-cell clonality testing is integral to the diagnostic work-up of T-cell malignancies; however, current methods lack specificity and sensitivity, which can make the diagnostic process difficult. The recent discovery of a monoclonal antibody (mAb) specific for human TRBC1 will greatly improve the outlook for T-cell malignancy diagnostics. The anti-TRBC1 mAb can be used in flow cytometry immunophenotyping assays to provide a low-cost, robust, and highly specific test that detects clonality of immunophenotypically distinct T-cell populations. Recent studies demonstrate the clinical utility of this approach in several contexts; use of this antibody in appropriately designed flow cytometry panels improves detection of circulating disease in patients with cutaneous T-cell lymphoma, eliminates the need for molecular clonality testing in the context of large granular lymphocyte leukemia, and provides more conclusive results in the context of many other T-cell disorders. It is worth noting that the increased ability to detect discrete clonal T-cell populations means that identification of T-cell clones of uncertain clinical significance (T-CUS) will become more common. This review discusses this new antibody and describes how it defines clonal T-cells. We present and discuss assay design and summarize findings to date about the use of flow cytometry TRBC1 analysis in the field of diagnostics, including lymph node and fluid sample investigations. We also make suggestions about how to apply the assay results in clinical work-ups, including how to interpret and report findings of T-CUS. Finally, we highlight areas that we think will benefit from further research