The immunophenotypes of blast cells in B-cell precursor acute lymphoblastic leukemia: How different are they from their normal counterparts?

Acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) is a haematological malignancy characterized by the uncontrolled proliferation of immature lymphoid cells. Over past decades, significant progress has been made in understanding the biology of ALL, resulting in remarkable improvements in its diagnosis, treatment and monitoring. Since the advent of chemotherapy, ALL has been the platform to test for innovative approaches applicable to cancer in general. For example, the advent of omics medicine has led to a deeper understanding of the molecular and genetic features that underpin ALL. Innovations in genomic profiling techniques have identified specific genetic alterations and mutations that drive ALL, inspiring new therapies. Targeted agents, such as tyrosine kinase inhibitors and immunotherapies, have shown promising results in subgroups of patients while minimizing adverse effects. Furthermore, the development of chimeric antigen receptor T cell therapy represents a breakthrough in ALL treatment, resulting in remarkable responses and potential long-term remissions. Advances are not limited to treatment modalities alone. Measurable residual disease monitoring and ex vivo drug response profiling screening have provided earlier detection of disease relapse and identification of exceptional responders, enabling clinicians to adjust treatment strategies for individual patients. Decades of supportive and prophylactic care have improved the management of treatment-related complications, enhancing the quality of life for patients with ALL.

Deciphering stage 0 hematogones by flow cytometry in follow-up bone marrow samples of pediatric B-Acute lymphoblastic leukemia cases: A potential mimicker of residual disease after anti CD19 therapy

CD19 is frequently targeted for immunotherapy in B cell malignancies, which may result in loss of CD19 expression in leukemic cells as an escape mechanism. Stage 0 hematogones (Hgs) are normal CD19-negative very early B cell precursors that can be potentially mistaken for CD19 negative residual leukemic cells by flow cytometry (FCM) in B cell acute lymphoblastic leukemia (BCP-ALL) cases treated with anti CD19 therapy. Our main objective was to characterize and study the incidence of stage 0 hematogones in follow-up bone marrow samples of pediatric BCP-ALL cases. We analyzed the flow cytometry standard files of 61 pediatric BCP-ALL cases treated with conventional chemotherapy and targeted anti-CD19 therapy, for identifying the residual disease and normal B cell precursors including stage 0 Hgs. A non-CD19 alternate gating strategy was used to isolate the B cells for detecting the residual disease and stage 0 Hgs. The stage 0 Hgs were seen in 95% of marrow samples containing CD19+ Hgs. When compared with controls and posttransplant marrow samples, the fraction of stage 0 Hgs was higher in patients receiving anti CD19 therapy (p = 0.0048), but it was not significant when compared with patients receiving chemotherapy (p = 0.1788). Isolated stage 0 Hgs are found in samples treated with anti-CD19 therapy simulating CD19 negative residual illness. Our findings aid in understanding the stage 0 Hgs and its association with CD19+ Hgs in anti CD19 therapy and conventional chemotherapy. This is crucial as it can be potentially mistaken for residual disease in patients treated with anti CD19 therapy.

Defining the Basal and Immunomodulatory Mediator-Induced Phosphoprotein Signature in Pediatric B Cell Acute Lymphoblastic Leukemia (B-ALL) Diagnostic Samples

It is theorized that dysregulated immune responses to infectious insults contribute to the development of pediatric B-ALL. In this context, our understanding of the immunomodulatory-mediator-induced signaling responses of leukemic blasts in pediatric B-ALL diagnostic samples is rather limited. Hence, in this study, we defined the signaling landscape of leukemic blasts, as well as normal mature B cells and T cells residing in diagnostic samples from 63 pediatric B-ALL patients. These samples were interrogated with a range of immunomodulatory-mediators within 24 h of collection, and phosflow analyses of downstream proximal signaling nodes were performed. Our data reveal evidence of basal hyperphosphorylation across a broad swath of these signaling nodes in leukemic blasts in contrast to normal mature B cells and T cells in the same sample. We also detected similarities in the phosphoprotein signature between blasts and mature B cells in response to IFNγ and IL-2 treatment, but significant divergence in the phosphoprotein signature was observed between blasts and mature B cells in response to IL-4, IL-7, IL-10, IL-21 and CD40 ligand treatment. Our results demonstrate the existence of both symmetry and asymmetry in the phosphoprotein signature between leukemic and non-leukemic cells in pediatric B-ALL diagnostic samples.

ANPELA: Significantly Enhanced Quantification Tool for Cytometry-Based Single-Cell Proteomics

ANPELA is widely used for quantifying traditional bulk proteomic data. Recently, there is a clear shift from bulk proteomics to the single-cell ones (SCP), for which powerful cytometry techniques demonstrate the fantastic capacity of capturing cellular heterogeneity that is completely overlooked by traditional bulk profiling. However, the in-depth and high-quality quantification of SCP data is still challenging and severely affected by the large numbers of quantification workflows and extreme performance dependence on the studied datasets. In other words, the proper selection of well-performing workflow(s) for any studied dataset is elusory, and it is urgently needed to have a significantly enhanced and accelerated tool to address this issue. However, no such tool is developed yet. Herein, ANPELA is therefore updated to its 2.0 version (https://idrblab.org/anpela/), which is unique in providing the most comprehensive set of quantification alternatives (>1000 workflows) among all existing tools, enabling systematic performance evaluation from multiple perspectives based on machine learning, and identifying the optimal workflow(s) using overall performance ranking together with the parallel computation. Extensive validation on different benchmark datasets and representative application scenarios suggest the great application potential of ANPELA in current SCP research for gaining more accurate and reliable biological insights.

Hematogones: The Supreme Mimicker and a Cytomorphological Confounder in Acute Lymphoblastic Leukemia

Objective B-lymphocyte progenitors, namely the hematogones (HGs), may pose problems in morphological assessment of bone marrow, not only during the diagnostic workup but also while evaluating bone marrow for remission status following chemotherapy. Here, we describe a series of 12 cases of acute lymphoblastic leukemia (ALL) that included both B-ALL and T-ALL cases, which were evaluated for remission status and revealed blast-like mononuclear cells in bone marrow in the range of 6 to 26%, which on immunophenotypic analysis turned out to be HGs.

Materials and Methods This is a case series of 12 ALL cases who were undergoing treatment at the Army Hospital (Referral and Research), New Delhi. All these cases were under workup for post-induction status (day 28) and to check for suspected ALL relapse. Bone marrow aspirate (BMA), biopsy, and immunophenotyping were performed. Multicolored flow cytometry was performed using CD10, CD20, CD22, CD34, CD19, and CD38 antibodies panel.

Results BMA assessment of 12 cases revealed a maximum of 26% blastoid cells and a minimum of up to 6%, raising the suspicion of hematological relapse. However, on clinical assessment, these patients were well preserved, with preserved peripheral counts. Hence, marrow aspirates were subjected to flow cytometry using the CD markers panel, as discussed above, which revealed HGs. These cases were followed by minimal residual disease (MRD) analysis that revealed MRD-negative status, further confirming our findings.

Conclusion This case series highlights the importance of morphology and bone marrow immunophenotyping in unveiling the diagnostic dilemma in post-induction ALL patients.

Targeting CD10 on B-Cell Leukemia Using the Universal CAR T-Cell Platform (UniCAR)

Chimeric antigen receptor (CAR)-expressing T-cells are without a doubt a breakthrough therapy for hematological malignancies. Despite their success, clinical experience has revealed several challenges, which include relapse after targeting single antigens such as CD19 in the case of B-cell acute lymphoblastic leukemia (B-ALL), and the occurrence of side effects that could be severe in some cases. Therefore, it became clear that improved safety approaches, and targeting multiple antigens, should be considered to further improve CAR T-cell therapy for B-ALL. In this paper, we address both issues by investigating the use of CD10 as a therapeutic target for B-ALL with our switchable UniCAR system. The UniCAR platform is a modular platform that depends on the presence of two elements to function. These include UniCAR T-cells and the target modules (TMs), which cross-link the T-cells to their respective targets on tumor cells. The TMs function as keys that control the switchability of UniCAR T-cells. Here, we demonstrate that UniCAR T-cells, armed with anti-CD10 TM, can efficiently kill B-ALL cell lines, as well as patient-derived B-ALL blasts, thereby highlighting the exciting possibility for using CD10 as an emerging therapeutic target for B-cell malignancies.

Development of CAR T Cell Therapy in Children-A Comprehensive Overview

CAR T cell therapy has revolutionized immunotherapy in the last decade with the successful establishment of chimeric antigen receptor (CAR)-expressing cellular therapies as an alternative treatment in relapsed and refractory CD19-positive leukemias and lymphomas. There are fundamental reasons why CAR T cell therapy has been approved by the Food and Drug administration and the European Medicines Agency for pediatric and young adult patients first. Commonly, novel therapies are developed for adult patients and then adapted for pediatric use, due to regulatory and commercial reasons. Both strategic and biological factors have supported the success of CAR T cell therapy in children. Since there is an urgent need for more potent and specific therapies in childhood malignancies, efforts should also include the development of CAR therapeutics and expand applicability by introducing new technologies. Basic aspects, the evolution and the drawbacks of childhood CAR T cell therapy are discussed as along with the latest clinically relevant information.

Hematogones with light chain restriction: A potential diagnostic pitfall when using flow cytometry analysis to assess bone marrow specimens

Light-chain restricted hematogones (LCR HGs) detected by flow cytometry analysis can mimic bone marrow involvement by B-cell lymphoma. This phenomenon can present a diagnostic pitfall and negatively impact patient management, as misinterpretation may upgrade disease stage. In this study, we characterized the immunophenotype of LCR HGs with an aim to differentiate them from B-cell lymphoma. We analyzed 24 patients with LCR HGs, 12 (50 %) were kappa light chain restricted and 12 (50 %) were lambda light chain restricted. LCR HGs account for 51 % (range, 1.5%-99%) of B cells, and 0.5 % (range, 0.1%-3.7%) of total cells. In 15 patients in whom multiple specimens were analyzed, 10 (67 %) showed persistent LCR HGs in more than 1 specimen, and the duration of the light chain restriction ranged from 4 months to 2 years. Among 24 patients, 4 (16.6 %) cases were concurrently involved by B-cell lymphoma/myeloma in addition to LCR HGs. With the exception of light chain restriction, LCR HGs showed a similar immunophenotype as normal HGs and had a distinct location on the CD45/Side Scatter (SSC) plot. They were also consistently positive for CD10, CD19, CD38 (bright), CD43, and CD200. CD20 expression showed a spectrum from dim/negative to positive.

Monitoring minimal/measurable residual disease in B-cell acute lymphoblastic leukemia by flow cytometry during targeted therapy

B-cell acute lymphoblastic leukemia (B-ALL) is a hematologic malignancy of B-type lymphoid precursor cells. Minimal/measurable residual disease (MRD) is an important prognostic factor for B-ALL relapse. Traditional flow cytometry detection mainly relies on CD19-based gating strategies. However, relapse of CD19-negative B-ALL frequently occurs in patients who receive cellular and targeted therapy. This review will summarize the technical aspects of standard MRD assessment in B-ALL by flow cytometry, and then discuss the challenges of MRD strategies to deal with the scenario of CD19 negative or dim B-ALL relapse.

Immunophenotypic shift in the B-cell precursors from regenerating bone marrow samples: A critical consideration for measurable residual disease assessment in B-lymphoblastic leukemia

Accurate knowledge of expression patterns/levels of commonly used MRD markers in regenerative normal-B-cell-precursors (BCP) is highly desirable to distinguish leukemic-blasts from regenerative-BCP for multicolor flow cytometry (MFC)-based measurable residual disease (MRD) assessment in B-lymphoblastic leukemia (B-ALL). However, the data highlighting therapy-related immunophenotypic-shift in regenerative-BCPs is scarce and limited to small cohort. Herein, we report the in-depth evaluation of immunophenotypic shift in regenerative-BCPs from a large cohort of BALL-MRD samples. Ten-color MFC-MRD analysis was performed in pediatric-BALL at the end-of-induction (EOI), end-of-consolidation (EOC), and subsequent-follow-up (SFU) time-points. We studied normalized-mean fluorescent intensity (nMFI) and coefficient-of-variation of immunofluorescence (CVIF) of CD10, CD19, CD20, CD34, CD38, and CD45 expression in regenerative-BCP (early, BCP1 and late, BCP2) from 200 BALL-MRD samples, and compared them with BCP from 15 regenerating control (RC) TALL-MRD samples and 20 treatment-naïve bone-marrow control (TNSC) samples. Regenerative-BCP1 showed downregulation in CD10 and CD34 expression with increased CVIF and reduced nMFI (p < 0.001), upregulation of CD20 with increased nMFI (p = 0.014) and heterogeneous CD45 expression with increased CVIF (p < 0.001). Immunophenotypic shift was less pronounced in the BCP2 compared to BCP1 compartment with increased CVIF in all but CD45 (p < 0.05) and reduced nMFI only in CD45 expression (p = 0.005). Downregulation of CD10/CD34 and upregulation of CD20 was higher at EOI than EOC and SFU time-points (p < 0.001). Regenerative-BCPs are characterized by the significant immunophenotypic shift in commonly used B-ALL-MRD markers, especially CD10 and CD34 expression, as compared to treatment-naïve BCPs. Therefore, the templates/database for BMRD analysis must be developed using regenerative-BCP.

The prognostic significance of hematogones and CD34+ myeloblasts in bone marrow for adult B-cell lymphoblastic leukemia without minimal residual disease

This study was aimed to dissect the prognostic significances of hematogones and CD34+ myeloblasts in bone marrow for adult B-cell acute lymphoblastic leukemia(ALL) without minimal residual disease(MRD) after the induction chemotherapy cycle. A total of 113 ALL patients who have received standardized chemotherapy cycle were analyzed. Cases that were not remission after induction chemotherapy or have received stem cell transplantation were excluded. Flow cytometry was used to quantify the levels of hematogones and CD34+ myeloblasts in bone marrow aspirations, and the patients were grouped according to the levels of these two precursor cell types. The long-term relapse-free survival(RFS) and recovery of peripheral blood cells of each group after induction chemotherapy were compared. The results indicated that, after induction chemotherapy, patients with hematogones ≥0.1% have a significantly longer remission period than patients with hematogones <0.1% (p = 0.001). Meanwhile, the level of hematogones was positively associated with the recovery of both hemoglobin and platelet in peripheral blood, while CD34+ myeloblasts level is irrelevant to the recovery of Hb and PLT in peripheral blood, level of hematogones and long-term prognosis. This study confirmed hematogones level after induction chemotherapy can be used as a prognostic factor for ALL without MRD. It is more applicable for evaluation prognosis than CD34+ myeloblasts.

Relative safety of various spermatogenic stem cell purification methods for application in spermatogenic stem cell transplantation

BACKGROUND

Spermatogonial stem cell (SSC) transplantation technology as a promising option for male fertility preservation has received increasing attention, along with efficient SSC purification technology as a necessary technical support; however, the safety of such application in patients with tumors remains controversial.

METHODS

In this study, we used a green fluorescent protein mouse xenograft model of B cell acute lymphocytic leukemia. We isolated and purified SSCs from the testicular tissue of model mice using density gradient centrifugation, immune cell magnetic bead separation, and flow cytometry. The purified SSCs were transplanted into convoluted seminiferous tubules of the nude mice and C57BL/6 male mice subjected to busulfan. The development and proliferation of SSCs in the recipient testis were periodically tested, along with whether B cell acute lymphocytic leukemia was induced following SSC implantation. The genetic characteristics of the offspring obtained from natural mating were also observed.

RESULTS

In testicular leukemia model mice, a large number of BALL cells infiltrated into the seminiferous tubule, spermatogenic cells, and sperm cells in the testis tissue decreased. After spermatogonial stem cell transplantation, the transplanted SSCs purified by immunomagnetic beads and flow cytometry methods colonized and proliferated extensively in the basement of the seminiferous tubules of mice; a large number of spermatogenic cells and sperm were found in recipient testicular tissue after 12 weeks of SSC transplantation. In leukemia detection in nude mice after transplantation in the three SSC purification groups, a large number of BALL cells could be detected in the blood of recipient mice 2-3 weeks after transplantation in the density gradient centrifugation group, but not in the blood of the flow cytometry sorting group and the immunomagnetic bead group after 16 weeks of observation.

CONCLUSIONS

In this study, we confirmed that immunomagnetic beads and flow cytometry methods of purifying SSCs from the testicular tissue of the testicular leukemia mouse model could be safely applied to the SSC transplantation technology without concomitant tumor implantation. The results thus provide a theoretical basis for the application of tumor SSC cryopreservation for fertility preservation in patients with tumors.

Immunophenotyping of Murine Precursor B-Cell Leukemia/Lymphoma: A Comparison of Immunohistochemistry and Flow Cytometry

In humans and in mouse models, precursor B-cell lymphoblastic leukemia (B-ALL)/lymphoblastic lymphoma (B-LBL) can be classified as either the pro-B or pre-B subtype. This is based on the expression of antigens associated with the pro-B and pre-B stages of B-cell development. Antigenic markers can be detected by flow cytometry or immunohistochemistry (IHC), but no comparison of results from these techniques has been reported for murine B-ALL/LBL. In our analysis of 30 cases induced by chemical or viral mutagenesis on a WT or Pax5+/- background, 18 (60%) were diagnosed as pro-B by both flow cytometry and IHC. Discordant results were found for 12 (40%); 6 were designated pro-B by IHC and pre-B by flow cytometry and the reverse for the remaining 6 cases. Discordance occurred because different markers were used to define the pro-B-to-pre-B transition by IHC vs flow cytometry. IHC expression of cytoplasmic IgM (μIgM) defined the pre-B stage, whereas the common practice of using CD25 as a surrogate marker in flow cytometry was employed here. These results show that CD25 and μIgM are not always concurrently expressed in B-ALL/LBL, in contrast to normal B-cell development. Therefore, when subtyping B-ALL/LBL in mice, an IHC panel of B220, PAX5, TdT, c-Kit/CD117, CD43, IgM, and ΚLC should be considered. For flow cytometry, cytoplasmic IgM may be an appropriate marker in conjunction with the surface markers B220, CD19, CD43, c-Kit/CD117, BP-1, and CD25.

Proteomic tools and new insights for the study of B-cell precursor acute lymphoblastic leukemia

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is a hematological malignancy of immature B-cell precursors, affecting children more often than adults. The etiology of BCP-ALL is still unknown, but environmental factors, sex, race or ethnicity, and genomic alterations influence the development of the disease. Tools based on protein detection, such as flow cytometry, mass spectrometry, mass cytometry and reverse phase protein array, represent an opportunity to investigate BCP-ALL pathogenesis and to identify new biomarkers of disease. This review aims to document the recent advancements with respect to applications of proteomic technologies to study mechanisms of leukemogenesis, how this information could be used in the discovery of biological targets, and finally we describe the challenges of application of proteomic tools for the approach of BCP-ALL.

Easy discrimination of hematogones from lymphoblasts in B-cell progenitor acute lymphoblastic leukemia patients using CD81/CD58 expression ratio

INTRODUCTION

The discrimination of leukemia lymphoblasts (LB) in diagnosis and follow-up of B-cell progenitor acute lymphoblastic leukemia (BCP-ALL) by multiparameter flow cytometry (MFC) may be difficult due to the presence of hematogones (HG). The aim of this study was to compare lymphoblasts of BCP-ALL and HG for the expression of the most discriminating antigens.

METHODS

A total of 82 bone marrow samples (39 BCP-ALL and 43 patients with HG) were analyzed using MFC. Mean fluorescence intensity (MFI) was measured for ten markers commonly used in hematology laboratories: CD45, CD19, CD10, CD34, CD38, CD20, CD22, CD58, CD81, and CD123. Statistical comparison of the MFI between LB and HG was performed. The presence on LB of aberrant expression of myeloid and/or T-cell markers was also investigated.

RESULTS

Qualitative pattern expression of antigens showed overexpression on LB of CD58, CD22, CD34, CD10 and underexpression of CD81, CD45, CD38 when compared to HG. Expression of CD123 was positive in 34% of BCP-ALL LB and always absent on HG. Aberrant antigen expression (myeloid and/or T-cell marker) including CD123 was observed in 58% of BCP-ALL patients. The use of a MFI antigen ratio of the most discriminating markers (CD81/CD58) (analysis of variance, P < 0.005) increased the distinction of LB versus HG with a high specificity and sensitivity as demonstrated by the use of ROC curve analysis (AUC of CD81/CD58: 0.995).

CONCLUSION

We demonstrate in this study that routine use of the MFI antigen ratio (CD81/CD58) in addition to the MFC evaluation using WHO classical criteria appears to be an efficient approach to discriminate LB from HG.

Surface expression of Cytokine Receptor-Like Factor 2 increases risk of relapse in pediatric acute lymphoblastic leukemia patients harboring IKZF1 deletions

We prospectively examined whether surface expression of Cytokine Receptor-Like Factor 2 (CRLF2) on leukemic blasts is associated with survival and induction treatment response in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL) patients. Flow cytometric analysis of bone marrow-derived leukemia cells revealed that 7.51% (29/286) of 386 pediatric BCP-ALL patients were CRLF2-positive (CRLF2pos) at diagnosis. The median minimal residual disease (MRD) was lower in CRLF2pos than CRLF2-negative (CRLF2neg) patients on day 15 (MRD15) after induction therapy [0.01% (0.001-0.42%) vs. 0.45% (0.05-3.50%); p=0.001]. By contrast, the MRD15 was higher in Ikaros family Zinc Finger Protein 1 (IKZF1)-deleted BCP-ALL patients than in BCP-ALL patients without IKZF1 deletions [1.18% (0.06-12.0%) vs 0.33% (0.03-2.6%); p=0.003]. Subgroup analysis showed that MRD15 levels were lower in IKZF1Δ/CRLF2pos patients than in IKZF1Δ/CRLF2neg patients [0.1% (0.02-5.06%) vs. 2.9% (0.25-12%); p=0.005]. Furthermore, MRD15 levels were higher in IKZF1WT/CRLF2neg patients than in IKZF1WT/CRLF2pos patients [0.40% (0.04-2.7%) vs. 0.001% (0.001-0.01%)]. Despite the low MRD15 levels, IKZF1Δ/CRLF2pos patients showed poorer relapse-free survival (RFS) than other patient groups (p=0.003). These findings demonstrate that surface CRLF2 expression is associated with increased risk of relapse in pediatric BCP-ALL patients harboring IKZF1 deletions.

Differential expression of CD73, CD86 and CD304 in normal vs. leukemic B-cell precursors and their utility as stable minimal residual disease markers in childhood B-cell precursor acute lymphoblastic leukemia

BACKGROUND

Optimal discrimination between leukemic blasts and normal B-cell precursors (BCP) is critical for treatment monitoring in BCP acute lymphoblastic leukemia (ALL); thus identification of markers differentially expressed on normal BCP and leukemic blasts is required.

METHODS

Multicenter analysis of CD73, CD86 and CD304 expression levels was performed in 282 pediatric BCP-ALL patients vs. normal bone marrow BCP, using normalized median fluorescence intensity (nMFI) values.

RESULTS

CD73 was expressed at abnormally higher levels (vs. pooled normal BCP) at diagnosis in 71/108 BCP-ALL patients (66%), whereas CD304 and CD86 in 119/202 (59%) and 58/100 (58%) patients, respectively. Expression of CD304 was detected at similar percentages in common-ALL and pre-B-ALL, while found at significantly lower frequencies in pro-B-ALL. A significant association (p = 0.009) was found between CD304 expression and the presence of the ETV6-RUNX1 fusion gene. In contrast, CD304 showed an inverse association with MLL gene rearrangements (p = 0.01). The expression levels of CD73, CD86 and CD304 at day 15 after starting therapy (MRD15) were stable or higher than at diagnosis in 35/37 (95%), 40/56 (71%) and 19/41 (46%) cases investigated, respectively. This was also associated with an increased mean nMFI at MRD15 vs. diagnosis of +24 and +3 nMFI units for CD73 and CD86, respectively. In addition, gain of expression of CD73 and CD86 at MRD15 for cases that were originally negative for these markers at diagnosis was observed in 16% and 18% of cases, respectively. Of note, CD304 remained aberrantly positive in 63% of patients, despite its levels of expression decreased at follow-up in 54% of cases.

CONCLUSIONS

Here we show that CD73, CD86 and CD304 are aberrantly (over)expressed in a substantial percentage of BCP-ALL patients and that their expression profile remains relatively stable early after starting therapy, supporting their potential contribution to improved MRD analysis by flow cytometry.

Immunophenotypic aberrancies in acute lymphoblastic leukemia from 282 Iraqi patients

INTRODUCTION

The identification of aberrancies in leukemia-associated immunophenotype (LAIP) of acute lymphoblastic leukemia (ALL) is quite important in the assessment of minimal residual disease (MRD). This study, the first from Iraq, aimed to assess the frequency and patterns of LAIP among Iraqi patients with ALL, to establish future strategies for evaluating MRD.

METHODS

A total of 282 newly diagnosed Iraqi ALL cases were analyzed with six-parameter flow cytometry using a panel of 29 monoclonal antibodies.

RESULTS

Immunological subtyping revealed that 85.5% of cases were B-ALL and the remainder T-ALL. LAIP was detected in 97.1% of B-ALL, and in 26.8% of T-ALL. The asynchronous maturation-associated antigen patterns in B-ALL were CD10^strong+ /TdT^dim+ , CD38^dim+ /CD34⁺ , CD10^dim+ /CD34⁺ , CD10^strong /CD20^strong+ , CD20^strong+ /CD34^+, and CD45^dim+ /CD20^strong+ in 84.6%, while the cross-lineage myeloid expression was seen in 81.3% and aberrant T-cell antigen expression in 6.2%. For T-ALL, asynchronous maturation-associated antigen patterns included the following: CD1a⁺ /CD5⁺ /sCD3⁺ and CD34⁺ /sCD3⁺ in 12.2%. Myeloid and B-cell antigen expression were each identified in 7.3% of T-ALL. No significant differences in LAIP were found between children and adults.

CONCLUSION

The high rates and the patterns of LAIP particularly in Iraqi B-ALL patients may allow the development of more cost-effective strategies for MRD monitoring.

Bone marrow plasma cells are a primary source of serum HIV-1-specific antibodies in chronically infected individuals

Several potent and broadly neutralizing Abs to HIV-1 have been isolated recently from peripheral blood B cells of infected individuals, based on prescreening of Ab activity in the serum. However, little is known regarding the cells that make the Abs that circulate in the blood. Accordingly, we investigated the most likely source, the bone marrow, of chronically HIV-1-infected individuals who were not receiving antiretroviral therapy. Increased frequencies of plasma cells, as well as B cell precursors, namely preB-I and preB-II, and decreased frequencies of mature B cells were observed in bone marrow aspirates of these individuals compared with HIV-negative counterparts. Increased frequencies of bone marrow plasma cells are consistent with known hallmarks of HIV-1 infection, namely hypergammaglobulinemia and increased frequencies of peripheral blood plasmablasts. Levels of HIV-1 envelope (Env)-binding and HIV-1-neutralizing Abs were measured in serum, and corresponding frequencies of Ab-secreting or Env-binding cells were measured in the blood (plasmablasts and memory B cells) and in the bone marrow (plasma cells). A strong correlation was observed between serum HIV-1-specific Abs and Env-specific bone marrow-derived plasma cells, but not circulating plasmablasts or memory B cells. These findings demonstrate that, despite HIV-1-induced phenotypic and functional B cell dysregulation in the peripheral blood and secondary lymphoid tissues, bone marrow plasma cells remain a primary source for circulating HIV-1-specific Abs in HIV-1-infected individuals.