Comparison of gene expression and flow cytometry for immune profiling in chronic lymphocytic leukaemia

Understanding how cancer and cancer therapies affect the immune system is integral to the rational application of immunotherapies. Flow cytometry is the gold standard method of peripheral blood immune cell profiling. However, the requirement for viable cells can limit its applicability, especially in studies of retrospective clinical cohorts. We aimed to determine if gene expression, analysed using the NanoString platform, could be used to quantify the immune populations present in cryopreserved peripheral blood mononuclear cell (PBMC) samples from patients with chronic lymphocytic leukaemia. Cell abundance scores derived from gene expression analysis were significantly correlated with the population frequency quantified by flow cytometry for all subsets analysed, including T cells, NK cells and Monocytes. This study demonstrates that gene expression analysis can be applied to cryopreserved PBMC and provides a concordant and complementary understanding of the immune profile to flow cytometry.

Imaging the Zigzag Wigner Crystal in Confinement-Tunable Quantum Wires

The existence of Wigner crystallization, one of the most significant hallmarks of strong electron correlations, has to date only been definitively observed in two-dimensional systems. In one-dimensional (1D) quantum wires Wigner crystals correspond to regularly spaced electrons; however, weakening the confinement and allowing the electrons to relax in a second dimension is predicted to lead to the formation of a new ground state constituting a zigzag chain with nontrivial spin phases and properties. Here we report the observation of such zigzag Wigner crystals by use of on-chip charge and spin detectors employing electron focusing to image the charge density distribution and probe their spin properties. This experiment demonstrates both the structural and spin phase diagrams of the 1D Wigner crystallization. The existence of zigzag spin chains and phases which can be electrically controlled in semiconductor systems may open avenues for experimental studies of Wigner crystals and their technological applications in spintronics and quantum information.

Abstract 1548: Genetic biomarkers predict clinical response and survival in myelodysplasia

Background: Hypomethylating agents (HMA) used in higher-risk myelodysplastic syndromes (MDS) improve survival but HMA-failure has a poor prognosis. Abnormal bone marrow (BM) colony-forming units (CFUs) persist in treated MDS patients despite achievement of complete remission, suggesting persistent abnormal stem cell function. We aim to identify genetic biomarkers following treatment with Azacitidine ± Thalidomide or Lenalidomide that predict clinical outcomes in MDS.

Methods: BM cells from patients enrolled in ALLG MDS3 and MDS4 clinical trials at baseline and after 4 cycles of treatment (C4) were grown in Methocult for 14 days. CFUs were pooled at baseline; C4 macroscopically normal and abnormal colonies were harvested separately. mRNA expression was quantified using the Nanostring nCounter PanCancer Pathways panel. Clinical outcomes analysed were: (1) clinical benefit at 12 months (haematological improvement or better as per IWG criteria) (2) best response achieved. Genes expressed above background level in ≥25% of samples were included for statistical analyses, resulting in 516 genes across 56 samples from 23 different patients. R limma package was used for differential expression analysis. Patients were weighted using limma's voomWithQualityWeights function. Moderated t-tests with empirical Bayes were done to identify differentially expressed genes. For testing between colonies, a log-fold-change cut-off of 0.5 was used with limma's treat function. P-values were adjusted for multiple hypothesis testing.

Results: 98 genes exhibited significantly different expression (p <0.05) when comparing C4 normal to baseline colonies and 118 genes were differentially expressed between C4 normal to C4 abnormal colonies. Key results are summarised: (1) Within C4 normal colonies - RFC3 (p=0.04) and LTBP1 (p=0.04) were upregulated in patients with clinical benefit at 12 months (2) Within C4 abnormal colonies - FN1 (p=0.03) was upregulated in those failing to achieve at least a partial response (PR) (3) Comparing C4 normal colonies to baseline: a. The top 5 differentially expressed genes: MAPK12, PLAU, FGFR1, IL10 and FLNA (p<0.001) were downregulated in the C4 normal group; b. In addition, for patients with clinical benefit, MYD88 and PIK3R5 were downregulated (p<0.001) while; c. In patients who achieved at least a PR as best response, NFKB1, SYK and TGFBR2 were downregulated (p<0.001). d. Gene ontology analysis revealed upregulated genes involved in plasma membrane and cytokine production were over-represented at baseline while; e. KEGG pathway analysis showed upregulated genes involved in the cytokine receptor, Notch and NF-kB signalling pathways.

Conclusion: We identified changes in gene expression following treatment in MDS that predict outcomes in response and clinical benefit. These genetic biomarkers require further validation and could define early markers of resistance for investigation of novel therapies.

Citation Format: Lynette Chee, David Ritchie, Jessica Chung, Daniel Park, Mandy Ludford-Menting, Jane Ripley, Melita Kenealy, Rachel Koldej. Genetic biomarkers predict clinical response and survival in myelodysplasia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1548.

Strategies to enhance the graft versus tumour effect after allogeneic haematopoietic stem cell transplantation

Relapse of haematological malignancies after allogeneic haematopoietic stem cell transplant is a major cause of mortality. The immunological mechanisms that may lead to disease relapse may include immunological immaturity prior to reconstitution of the allogeneic immune system, tumour antigen downregulation or promotion of T-cell exhaustion by interactions with the tumour microenvironment. Current therapeutic strategies for post-transplant relapse are limited in their efficacy and alternative approaches are required. In this review, we discuss the mechanisms of T and NK-cell immune evasion that facilitate relapse of haematological malignancies after allogeneic stem cell transplantation, and explore emerging strategies to augment the allogeneic immune system in order to construct a more potent graft versus tumour response.

Detection of alpha-synuclein conformational variants from gastro-intestinal biopsy tissue as a potential biomarker for Parkinson's disease

Aims

Gastrointestinal (GI) α‐synuclein (aSyn) detection as a potential biomarker of Parkinson's disease (PD) is challenged by conflicting results of recent studies. To increase sensitivity and specificity, we applied three techniques to detect different conformations of aSyn in GI biopsies obtained from a longitudinal, clinically well‐characterized cohort of PD patients and healthy controls (HC).

Methods

With immunohistochemistry (IHC), we used antibodies reactive for total, phosphorylated and oligomeric aSyn; with aSyn proximity ligation assay (AS‐PLA), we targeted oligomeric aSyn species specifically; and with paraffin‐embedded tissue blot (AS‐PET‐blot) we aimed to detect fibrillary, synaptic aSyn.

Results

A total of 163 tissue blocks were collected from 51 PD patients (113 blocks) and 21 HC (50 blocks). In 31 PD patients, biopsies were taken before the PD diagnosis (Prodromal); while in 20 PD patients biopsies were obtained after diagnosis (Manifest). The majority of tissues blocks were from large intestine (62%), followed by small intestine (21%), stomach (10%) and oesophagus (7%). With IHC, four staining patterns were detected (neuritic, ganglionic, epithelial and cellular), while two distinct staining patterns were detected both with AS‐PLA (cellular and diffuse signal) and with AS‐PET‐blot (aSyn‐localized and pericrypt signal). The level of agreement between different techniques was low and no single technique or staining pattern reliably distinguished PD patients (Prodromal or Manifest) from HC.

Conclusions

Our study suggests that detection of aSyn conformational variants currently considered pathological is not adequate for the diagnosis or prediction of PD. Future studies utilizing novel ultrasensitive amyloid aggregation assays may increase sensitivity and specificity.

Prognostic markers in core-binding factor AML and improved survival with multiple consolidation cycles of intermediate-/high-dose cytarabine

OBJECTIVES

Core-binding factor acute myeloid leukaemia (CBF AML) defined by t(8;21)(q22;q22) or inv(16)(p13q22)/t(16;16)(p13;q22) has a favourable prognosis; however, 30%-40% of patients still relapse after chemotherapy. We sought to evaluate the risk factors for relapse in a de novo CBF AML cohort.

PATIENTS/MATERIALS/METHODS

A retrospective review of patients from four Australian tertiary centres from 2001 to 2012, comprising 40 t(8;21) and 30 inv(16) AMLs.

RESULTS

Multivariate analysis identified age (P = .032) and white cell count (WCC)>40 (P = .025) as significant predictors for inferior OS and relapse, respectively. Relapse risk was higher in the inv(16) group vs the t(8;21) group (57% vs 18%, HR 4.31, 95% CI: 1.78-10.42, P = .001). Induction therapy had no bearing on OS or relapse-free survival (RFS); however, consolidation treatment with >3 cycles of intermediate-/high-dose cytarabine improved OS (P = .035) and RFS (P = .063). Five patients demonstrated post-treatment stable q PCR positivity without relapse.

CONCLUSIONS

>3 consolidation cycles of intermediate-/high-dose cytarabine improves patient outcomes Age and inv(16) CBF AML subtype are predictors of inferior OS and RFS, respectively. Stable low-level MRD by qPCR does not predict relapse Similar OS in the inv(16) cohort compared to the t(8;21) cohort, despite a higher relapse rate, confirms salvageability of relapsed disease.

Coherent Spin Amplification Using a Beam Splitter

We report spin amplification using a capacitive beam splitter in n-type GaAs where the spin polarization is monitored via a transverse electron focusing measurement. It is shown that partially spin-polarized current injected by the emitter can be precisely controlled, and the spin polarization associated with it can be amplified by the beam splitter, such that a considerably high spin polarization of around 50% can be obtained. Additionally, the spin remains coherent as shown by the observation of quantum interference. Our results illustrate that spin-polarization amplification can be achieved in materials without strong spin-orbit interaction.

Viral Respiratory Tract Infections in Allogeneic Hematopoietic Stem Cell Transplantation Recipients in the Era of Molecular Testing

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Rhinovirus caused the majority of vRTI episodes in first 100 days following transplantation.

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Progression to lower respiratory tract infection was seen in 30% of patients with vRTI.

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vRTI in first 100 days after transplantation is associated with morbidity (ie, ICU admission).

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All of the deaths in our study cohort occurred in patients who acquired vRTI within 30 days of transplantation.

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Previous autologous transplantation is a significant risk factor for vRTI.

Viral respiratory tract infection (vRTI) is a significant cause of morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). This study aimed to assess the epidemiologic characteristics, risk factors, and outcomes of vRTI occurring in the period from conditioning to 100 days after allo-HSCT in the era of molecular testing. This study was a retrospective record review of patients who underwent allo-HSCT at Royal Melbourne Hospital between January 2010 and December 2015. Symptomatic patients were tested using respiratory multiplex polymerase chain reaction (PCR). Logistic regression and Kaplan-Meier analysis were used to identify risk factors for vRTI and the risk of death or intensive care unit (ICU) admission, respectively. A total of 382 patients were reviewed, and 65 episodes of vRTI were identified in 56 patients (14.7%). Rhinovirus accounted for the majority of infections (69.2%). The majority of episodes presented initially with upper respiratory tract infection (58.5%), with 28.9% of them progressing to lower respiratory tract infection. Eleven episodes (16.9%) were associated with ICU admission. There were no deaths directly due to vRTI. Previous autologous HSCT was associated with an increased risk of vRTI (odds ratio, 2.1; 95% confidence interval, 1.0 to 4.1). The risks of death (P = .47) or ICU admission (P = .65) were not significantly different by vRTI status. vRTI is common in the first 100 days after allo-HSCT and is associated with ICU admission.

Engineering the spin polarization of one-dimensional electrons

We present results of magneto-focusing on the controlled monitoring of spin polarization within a one-dimensional (1D) channel, and its subsequent effect on modulating the spin-orbit interaction (SOI) in a 2D GaAs electron gas. We demonstrate that electrons within a 1D channel can be partially spin polarized as the effective length of the 1D channel is varied in agreement with the theoretical prediction. Such polarized 1D electrons when injected into a 2D region result in a split in the odd-focusing peaks, whereas the even peaks remain unaffected (single peak). On the other hand, the unpolarized electrons do not affect the focusing spectrum and the odd and even peaks remain as single peaks, respectively. The split in odd-focusing peaks is evidence of direct measurement of spin polarization within a 1D channel, where each sub-peak represents the population of a particular spin state. Confirmation of the spin splitting is determined by a selective modulation of the focusing peaks due to the Zeeman energy in the presence of an in-plane magnetic field. We suggest that the SOI in the 2D regime is enhanced by a stream of polarized 1D electrons. The spatial control of spin states of injected 1D electrons and the possibility of tuning the SOI may open up a new regime of spin-engineering with application in future quantum information schemes.

Irrigation and weed control alter soil microbiology and nutrient availability in North Carolina Sandhill peach orchards

Orchard management practices such as weed control and irrigation are primarily aimed at maximizing fruit yields and economic profits. However, the impact of these practices on soil fertility and soil microbiology is often overlooked. We conducted a two-factor experimental manipulation of weed control by herbicide and trickle irrigation in a nutrient-poor peach (Prunus persica L. cv. Contender) orchard near Jackson Springs, North Carolina. After three and eight years of treatments, an array of soil fertility parameters were examined, including soil pH, soil N, P and cation nutrients, microbial biomass and respiration, N mineralization, and presence of arbuscular mycorrhizal fungi (AMF). Three general trends emerged: 1) irrigation significantly increased soil microbial biomass and activity, 2) infection rate of mycorrhizal fungi within roots were significantly higher under irrigation than non-irrigation treatments, but no significant difference in the AMF community composition was detected among treatments, 3) weed control through herbicides reduced soil organic matter, microbial biomass and activity, and mineral nutrients, but had no significant impacts on root mycorrhizal infection and AMF communities. Weed-control treatments directly decreased availability of soil nutrients in year 8, especially soil extractable inorganic N. Weed control also appears to have altered the soil nutrients via changes in soil microbes and altered net N mineralization via changes in soil microbial biomass and activity. These results indicate that long-term weed control using herbicides reduces soil fertility through reducing organic C inputs, nutrient retention and soil microbes. Together, these findings highlight the need for alternative practices such as winter legume cover cropping that maintain and/or enhance organic inputs to sustain the soil fertility.

The CYP71AZ P450 Subfamily: A Driving Factor for the Diversification of Coumarin Biosynthesis in Apiaceous Plants

The production of coumarins and furanocoumarins (FCs) in higher plants is widely considered a model illustration of the adaptation of plants to their environment. In this report, we show that the multiplication of cytochrome P450 variants within the CYP71AZ subfamily has contributed to the diversification of these molecules. Multiple copies of genes encoding this enzyme family are found in Apiaceae, and their phylogenetic analysis suggests that they have different functions within these plants. CYP71AZ1 from Ammi majus and CYP71AZ3, 4, and 6 from Pastinaca sativa were functionally characterized. While CYP71AZ3 merely hydroxylated esculetin, the other enzymes accepted both simple coumarins and FCs. Superimposing in silico models of these enzymes led to the identification of different conformations of three regions in the enzyme active site. These sequences were subsequently utilized to mutate CYP71AZ4 to resemble CYP71AZ3. The swapping of these regions lead to significantly modified substrate specificity. Simultaneous mutations of all three regions shifted the specificity of CYP71AZ4 to that of CYP71AZ3, exclusively accepting esculetin. This approach may explain the evolution of this cytochrome P450 family regarding the appearance of FCs in parsnip and possibly in the Apiaceae.

Abstract 11: Progression from newly diagnosed multiple myeloma to relapsed refractory multiple myeloma is associated with significant alterations in the CD4+ Treg population phenotype

Introduction: Immune compromise is a recognized complication of multiple myeloma (MM), aging, and anti-MM therapies used throughout the course of the disease. Our group have previously reported that patients with relapsed/refractory MM (RRMM) have marked CD4+ T lymphopenia that is not present in newly diagnosed MM (NDMM) and does not recover with successive cycles of lenalidomide and dexamethasone (len/dex) treatment1,2. However, the proportion of Tregs within the CD4+ T-cell population (defined as CD127dimCD25hiFoxp3+) increased with successive cycles of treatment and approached normal range by cycle 9. We hypothesized that this represented homeostatic proliferation of peripherally-derived Tregs (pTreg) as opposed to thymic production of naturally-derived Tregs (nTreg), which can be differentiated by methylation status of the T-cell specific demethylation region (TSDR) found in intron 1 of the Foxp3 gene3. This bears relevance, as (a) pTregs are likely to be derived from senescent cells that are functionally different to recent thymic emigrants, (b) pTregs may exhibit plasticity, as opposed to nTregs, and (c) the population of effector memory T (TEM) cells may be compromised.

Methods: We sought to investigate at what point this change occurred throughout the course of disease in MM by analyzing 5 paired samples from patients with NDMM (ANZCTR trial ID ACTRN12613000344796) and RRMM (ANZCTR trial ID NCT00482261), and comparing with 5 age-matched normal donors. In the NDMM cohort, we examined Tregs from samples at baseline, after 4 cycles of len/dex, and after autologous stem cell transplant (ASCT), and in the RRMM cohort samples from baseline and after 9 cycles of len/dex. Tregs (defined as CD4+CD127-CD25+) were FACS sorted from each sample and DNA was extracted and bisulfite converted. The TSDR was PCR amplified using primers previously described3, and transformed into chemically competent E.coli. Individual colonies were picked and their DNA plasmids were sequenced. Cytosine matches/mismatches at CpG sites in the TSDR were identified and % methylation was calculated.

Results: The TSDR methylation status of Tregs from baseline NDMM patient samples is largely unmethylated and similar to age-matched controls, i.e., predominantly nTregs.

(1) The TSDR methylation status of Tregs from baseline RRMM patient samples is largely methylated, i.e., predominantly pTregs.

(2) Len/dex treatment in both NDMM and RRMM patient did not alter the respective phenotypes.

(3) After ASCT, 2 of the 5 NDMM patient samples analyzed had changed to a “pTreg phenotype.” Both these patients subsequently relapsed from complete remission, compared to 2 of 3 of the patients with an “nTreg phenotype” maintaining CR 8-9 years later.

Conclusions: This study adds evidence that the character of the CD4+ T cell population is radically altered in RRMM, compared with NDMM and age-matched controls. It is likely that thymic involution is a contributor to this, which is not only a normal occurrence with immunosenescence, but may be accelerated with ASCT in some patients. In this way, methylation status of the TSDR could potentially represent a biomarker for poorer prognosis.

References

1. Hsu A, Ritchie DS, Neeson,P. Are the immuno-stimulatory properties of Lenalidomide extinguished by co-administration of Dexamethasone? Oncoimmunology 2012;1:372-4.

2. Cooke RE et al. Spontaneous onset and transplant models of the Vk*MYC mouse show immunological sequelae comparable to human multiple myeloma. J Transl Med 2016;14:259.

3. Baron U et al. DNA demethylation in the human FOXP3 locus discriminates regulatory T cells from activated FOXP3(+) conventional T cells. Eur J Immunol 2007;37:2378-89.

Citation Format: Rachel Cooke, Hang Quach, Simon Harrison, Miles Prince, Rachel Koldej, David Ritchie. Progression from newly diagnosed multiple myeloma to relapsed refractory multiple myeloma is associated with significant alterations in the CD4+ Treg population phenotype [abstract]. In: Proceedings of the Second AACR Conference on Hematologic Malignancies: Translating Discoveries to Novel Therapies; May 6-9, 2017; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(24_Suppl):Abstract nr 11.

A hospital and home-based exercise program to address functional decline in people following allogeneic stem cell transplantation

PURPOSE

The aims of this study are to investigate the feasibility of an exercise program commencing 60 days following allogeneic stem cell transplantation (alloSCT), to investigate changes in physical function and health-related quality of life (HRQoL) in patients from pre- to post-alloSCT and to explore changes in patient outcomes before and after the program.

METHODS

This study is a single site, prospective case series including 43 adults undergoing alloSCT. The intervention was an 8-week outpatient and home-based exercise and education program. Outcomes included feasibility (consent, attendance, compliance and completion rates), functional exercise capacity (incremental shuttle walk test), muscle strength (hand-held dynamometry), self-efficacy for physical activity (Physical Activity Assessment Inventory) and HRQoL (Functional Assessment of Cancer Therapy-Bone Marrow Transplant). Outcomes were measured pre-alloSCT, 60 days post-alloSCT (pre-intervention) and 100 days post-alloSCT (post-intervention).

RESULTS

The consent rate was 93%. From baseline to 60 days post-alloSCT, there was significant decline in functional exercise capacity (mean difference 224 m, 95% CI 153-295, p < 0.0005), self-efficacy for physical activity (294 points, 95% CI 136-452, p = 0.001) and HRQoL (15 points, 95% CI 8-21, p < 0.0005). Ten participants did not commence the exercise program due to death (n = 5), illness (n = 1) or cancellation of alloSCT (n = 4). The intervention was feasible in those not affected by major medical complications or death. No adverse events occurred. From pre- to post-intervention, there was significant improvement in functional exercise capacity (p = 0.001) and HRQoL (p = 0.001).

CONCLUSIONS

AlloSCT results in significant decline in functional exercise capacity, self-efficacy for physical activity and HRQoL, which may be improved through an exercise program. This pilot demonstrated safety, feasibility and high patient interest. Further randomised research is required.

Low T-Cell Responses to Mitogen Stimulation Predicts Poor Survival in Recipients of Allogeneic Hematopoietic Stem Cell Transplantation

Background

Successful engraftment and reconstitution of the innate and adaptive immune system are associated with improved outcomes in recipients of allogeneic hematopoietic stem cell transplantation (HSCT). A clinically meaningful and simple biomarker of immunosuppression could potentially assist clinicians in their decision-making. We aimed to determine the relationship between T-cell production of interferon gamma (IFN-γ) in response to phytohemagglutinin (PHA) to clinical outcomes in HSCT recipients.

Methods

A prospective observational multicenter study of 73 adult allogeneic HSCT recipients was conducted in Melbourne, Australia. Eligible participants were >18 years and at risk of cytomegalovirus disease. T-cell responses to PHA were assessed at 3, 6, 9, and 12 months post-HSCT using the commercial quantiferon-cytomegalovirus assay, which quantifies IFN-γ production by ELISA following stimulation with PHA. A low response was defined as IFN-γ <0.5 IU/ml following stimulation with PHA.

Results

At 3 months post-HSCT, high responses to PHA (median IFN-γ 7.68 IU/ml) were seen in 63% of participants and low responses to PHA (median IFN-γ 0.06 IU/ml) in 37%. IFN-γ responses to PHA were significantly associated with the severity of acute graft versus host disease (AGVHD) (spearman r = −0.53, p < 0.001) and correlated with blood lymphocyte count (spearman r = 0.52, p < 0.001). Twelve month overall survival was greater in individuals with high compared to low IFN-γ response to PHA at 3 months [92 vs. 62%, respectively, Cox proportional hazard ratio (HR): 4.12 95% CI: 1.2–13.7, p = 0.02]. Non-relapse mortality (NRM) was higher in individuals with low IFN-γ response to PHA (competing risk regression HR 11.6 p = 0.02). In individuals with no AGVHD compared to AGVHD and high IFN-γ response to PHA compared to AGVHD and low IFN-γ response to PHA, 12-month survival was 100 vs. 80 vs. 52%, respectively (log rank test p < 0.0001).

Conclusion

Low IFN-γ response to PHA at the 3-month time-point following allogeneic HSCT was predictive of reduced 12-month overall survival, increased NRM, and reduced survival in recipients with AGVHD. Assessing IFN-γ response to PHA post-HSCT may be a clinically useful immune biomarker.

Predicting Risk of Infection in Patients with Newly Diagnosed Multiple Myeloma: Utility of Immune Profiling

Background

A translational study in patients with myeloma to determine the utility of immune profiling to predict infection risk in patients with hematological malignancy was conducted.

Methods

Baseline, end of induction, and maintenance peripheral blood mononuclear cells from 40 patients were evaluated. Immune cell populations and cytokines released from 1 × 10⁶ cells/ml cultured in the presence of a panel of stimuli (cytomegalovirus, influenza, S. pneumoniae, phorbol myristate acetate/ionomycin) and in media alone were quantified. Patient characteristics and infective episodes were captured from clinical records. Immunological variables associated with increased risk for infection in the 3-month period following sample collection were identified using univariate analysis (p < 0.05) and refined with multivariable analysis to define a predictive immune profile.

Results

525 stimulant samples with 19,950 stimulant–cytokine combinations across three periods were studied, including 61 episodes of infection. Mitogen-stimulated release of IL3 and IL5 were significantly associated with increased risk for subsequent infection during maintenance therapy. A lower Th1/Th2 ratio and higher cytokine response ratios for IL5 and IL13 during maintenance therapy were also significantly associated with increased risk for infection. On multivariable analysis, only IL5 in response to mitogen stimulation was predictive of infection. The lack of cytokine response and numerical value of immune cells were not predictive of infection.

Conclusion

Profiling cytokine release in response to mitogen stimulation can assist with predicting subsequent onset of infection in patients with hematological malignancy during maintenance therapy.

Temperature Dependence of Spin-Split Peaks in Transverse Electron Focusing

We present experimental results of transverse electron-focusing measurements performed using n-type GaAs. In the presence of a small transverse magnetic field (B_⊥), electrons are focused from the injector to detector leading to focusing peaks periodic in B_⊥. We show that the odd-focusing peaks exhibit a split, where each sub-peak represents a population of a particular spin branch emanating from the injector. The temperature dependence reveals that the peak splitting is well defined at low temperature whereas it smears out at high temperature indicating the exchange-driven spin polarisation in the injector is dominant at low temperatures.

Identifying Cytomegalovirus Complications Using the Quantiferon-CMV Assay After Allogeneic Hematopoietic Stem Cell Transplantation

Background

A simple test to identify recovery of CMV-specific T-cell immunity following hematopoietic stem cell transplantation (HSCT) could assist clinicians in managing CMV-related complications.

Methods

In an observational, multicenter, prospective study of 94 HSCT recipients we evaluated CMV-specific T-cell immunity at baseline, 3, 6, 9, and 12 months after transplant using the Quantiferon-CMV, an enzyme-linked immunosorbent spot assay (ELISpot), and intracellular cytokine staining.

Results

At 3 months after HSCT, participants who developed CMV disease (n = 8) compared with CMV reactivation (n = 26) or spontaneous viral control (n = 25) had significantly lower CD8+ T-cell production of interferon-γ (IFN-γ) in response to CMV antigens measured by Quantiferon-CMV (P = .0008). An indeterminate Quantiferon-CMV result had a positive predictive value of 83% and a negative predictive value of 98% for identifying participants at risk of further CMV reactivation. Participants experiencing CMV reactivation compared with patients without CMV reactivation had a reduced proportion of polyfunctional (IFN-γ+/tumor necrosis factor α-positive) CD4+ and CD8+ T cells and a higher proportion of interleukin 2-secreting cells (P = .01 and P = .002, respectively).

Conclusions

Quantifying CMV-specific T-cell immunity after HSCT can identify participants at increased risk of clinically relevant CMV-related outcomes.