Hiromichi Matsushita

Background and Objectives: Deep learning‐based systems have shown promise in automating white blood cell (WBC) classification; however, most validations are limited to single institutions. This study aimed to evaluate the multicenter performance and robustness of a CNN‐based deep learning system (DLS) for peripheral blood cell classification and morphologic abnormality detection across three hospitals. Methods: A total of 766 peripheral blood smears (613 routine and 153 abnormal) from Juntendo University Hospital, Kyoto University Hospital, and the National Cancer Center Hospital were analyzed using the Sysmex DI‐60. The DLS, trained on 1.49 million annotated cell images, classified 16 cell types and 42 morphological features. Cell classification performance was assessed by standard metrics, including accuracy and F 1 score, while agreement with manual WBC counts was evaluated through correlation and regression analyses. Results: The DLS achieved high specificity, negative predictive value, and accuracy (> 95%) across institutions. Mean F 1 scores exceeded 0.80 for major WBC types in both routine and abnormal smears. Agreement with manual microscopy was strong for neutrophils, lymphocytes, and eosinophils ( r ² > 0.8; Cb > 0.9), while monocytes and basophils showed moderate variability. The DLS identified smears containing blasts or abnormal cells that required expert review and detected morphological features associated with specific diseases. Conclusions: This multicenter validation demonstrates robust and reproducible performance of the DLS across laboratories, supporting its clinical applicability for routine WBC differentials and detection of disease‐specific morphological abnormalities.

Examination of the bone marrow (BM) remains fundamental to the diagnosis, classification, prognostication, and monitoring of hematolymphoid and other disorders affecting blood cell production. Since publication of the International Council for Standardization in Haematology (ICSH) guideline in 2008, advances in diagnostic technologies, disease classification systems and laboratory reporting practices have significantly evolved. These developments necessitate a framework to support contemporary BM evaluation and reporting. This document, prepared by an international ICSH Working Party, provides updated guidance on the examination and reporting of BM specimens and is an extension and refinement of the 2008 ICSH guidelines. It outlines the appropriate application and integration of key diagnostic modalities, including morphological assessment of BM aspirate and trephine biopsy specimens, immunophenotypic analysis by flow cytometry and immunohistochemistry and molecular genetic testing. Central to this guidance is the principle of integrated reporting, whereby findings from all diagnostic modalities are synthesized within the clinical context and aligned with current international classification systems. The ICSH acknowledges the emergence of automated digital microscopy, computational decision support tools, and other technological innovations in BM analysis. These developments hold considerable promise, but whilst many remain under evaluation, specific guidance regarding their routine clinical implementation is beyond the scope of this document.

The International Harmonisation Protocol (IHP) for Reticulocyte Percentage (%Retic) in CLSI‐H44‐A2 is a microscopic procedure performed on a new‐methylene‐blue‐stained blood film (NMB‐IHP). However, IHP‐compliant Measurement Procedures (MPs) based on flow cytometry (FCM) are recommended for practical and accurately assigned reference values. Thiazole orange (TO) for nucleic acid staining and CD235a immunostaining for erythrocyte gating are currently widespread for MP using FCM (TO/CD235a‐MP); however they have not been validated using NMB‐IHP. We recently developed MP using FCM with anti‐CD45/CD41a/CD61 antibodies, that are utilized for excluding platelets from the un‐nucleated blood cell fraction to select erythrocytes (TO/CD41a/CD61‐MP). The aim of this study is to validate TO/CD41a/CD61‐MP for measurement of reticulocytes as an IHP‐compliant MP. First, TO/CD235a‐MP was validated as an IHP‐compliant MP by comparing it with NMB‐IHP. Then TO/CD41a/CD61‐MP was compared with TO/CD235a‐MP. The practical utility of TO/CD41a/CD61‐MP was evaluated using XN‐2000™(Sysmex) and Celltac G + ™(Nihon Kohden) hematology analyzers to assess the accuracy of different nucleic acid staining methods. We first confirmed that TO/CD235a‐MP was consistent with NMB‐IHP, then evaluated TO/CD41a/CD61‐MP using TO/CD235a‐MP. Regression analysis demonstrated consistency between TO/CD41a/CD61‐MP and TO/CD235a‐MP, thereby establishing TO/CD41a/CD61‐MP as IHP‐compliant MP. In the accuracy assessment, the correlation coefficients to TO/CD41a/CD61‐MP were observed to be 0.97 for both hematology analyzers with %Retic ranging from 0.0 to 8.2. TO/CD41a/CD61‐MP serves effectively as an IHP‐compliant MP. This study provides the first empirical validation of FCM‐based MPs.

Background: The long-term immune implications of administering more than four doses of COVID-19 vaccine and the impact of breakthrough infections are not fully understood. Research Design and Methods: We conducted a follow-up cohort study on Japanese healthcare workers who received more than three doses of the BNT162b2 vaccine. We assessed both the anti-SARS-CoV-2 antibody titer and cellular immunity in 429 participants and investigated the numbers, types, and brands of COVID-19 vaccines administered, as well as the episodes of COVID-19 infections after the third dose. Results: Individuals who received three total doses of vaccines with BTI episodes demonstrated higher antibody titers than those who received four total doses of vaccines with no BTIs. The cellular immune responses between these two groups were comparable. Conclusions: These findings suggest that BTIs occurring after the primary series of COVID-19 vaccinations (first to third dose) induced humoral immunity to the spike protein that is greater than that induced by booster doses (fourth or fifth dose) and elicit cellular immunity to the spike protein comparable to that of booster doses.

Article Simple flow cytometry method using a myeloma panel that easily reveals clonal proliferation of mature B-cells was published on August 5, 2024 in the journal Clinical Chemistry and Laboratory Medicine (CCLM) (volume 0, issue 0).

The microtubule-associated protein MAP1B has been implicated in axonal growth and brain development. We found that MAP1B is highly expressed in the most aggressive and deadliest breast cancer subtype, triple-negative breast cancer (TNBC), but not in other subtypes. Expression of MAP1B was found to be highly correlated with poor prognosis. Depletion of MAP1B in TNBC cells impairs cell migration and invasion concomitant with a defect in tumorigenesis. We found that MAP1B interacts with key components for invadopodia formation, cortactin, and Tks5, the latter of which is a PtdIns(3,4)P2-binding and scaffold protein that localizes to invadopodia. We also found that Tks5 associates with microtubules and supports the association between MAP1B and α-tubulin. In accordance with their interaction, depletion of MAP1B leads to Tks5 destabilization, leading to its degradation via the autophagic pathway. Collectively, these findings suggest that MAP1B is a convergence point of the cytoskeleton to promote malignancy in TNBC and thereby a potential diagnostic and therapeutic target for TNBC.