Flow cytometric lymphocyte subset analysis (FCLSA) is essential for assessing immune status across various diseases and clinical settings. We surveyed current clinical laboratory practices related to FCLSA to establish a baseline reference for future standardization in Korea. Nine university hospitals actively performing FCLSA responded to the 22-question survey, which covered seven categories of laboratory practice. These hospitals used commercial reagent antibody kits from either Beckton Dickinson Biosciences (N = 4) or Beckman Coulter Diagnostics (N = 5). Most hospitals performed daily instrument setup and scheduled maintenance every 2–6 months. Two levels of commercial quality control materials were routinely used each day. Sample and reagent antibody volumes varied across hospitals, even when the same reagent kit was used. Acquired cell counts ranged from 5 × 10 3 to 5 × 10 4 cells, with two hospitals adjusting counts based on the cell type analyzed. Most laboratories reported percentages and general opinions; some additionally reported white blood cell and lymphocyte counts, along with lymphocyte percentages. This is the first comprehensive survey on the clinical laboratory practice of FCLSA in Korea.Standardization of FCLSA should be accelerated to ensure reliable and reproducible results.

Background: Current reference intervals for lymphocyte subpopulations are primarily based on Western populations, with limited data available for Korean children, particularly for extended subsets. We determined absolute cell counts and percentages of lymphocyte subpopulations in Korean children, according to age and sex. Methods: Samples from 92 children—stratified into two age groups, groups 1 (5–9 yrs) and 2 (10–17 yrs)—were obtained. Immunophenotyping was performed via flow cytometry using the Primary Immunodeficiency Orientation Tube (PIDOT) panel, primarily classifying the cells into T, B, and natural killer cell populations. T lymphocytes were divided into CD4+ , CD8+ , and CD4– CD8– subsets; T and B cells were further subdivided according to their maturation stage. Results: Children in group 1 exhibited higher absolute counts of total B cells, unswitched memory B cells/plasma cells, total T cells, CD4+ naïve cells, and TCRγδ+ T cells than those in group 2. In contrast, Group 2 children showed higher absolute counts of CD4+ effector memory (EM) T cells. Males had higher absolute counts of total B cells, particularly pregerminal center B cells, CD4+ EM cells, and CD8+ terminally differentiated T cells, whereas females showed higher proportions of CD4+ , CD4+ naïve, and CD8 + central memory/transitional memory T cells. Conclusions To the best of our knowledge, this study is the first to establish reference values for extended lymphocyte subsets in Korean children using the PIDOT panel. Age, sex, and laboratory-related factors influenced lymphocyte subset distributions. These findings may serve as reference data for immune disorders and immunotherapy in pediatric populations.

Informed consent for blood transfusion should include information that supports the decision to agree or disagree to the transfusion. Adverse reactions, including transfusion-transmitted infections, hemolysis, allergic reactions, fever, and volume overload, are listed in informed consent. Nevertheless, alloantibody formation, platelet refractoriness, and iron overload are not included in the informed consent. Therefore, a consent form that includes these factors should be considered for patients receiving transfusions to support decision-making.

Multiple myeloma (MM), a hematological malignancy, is characterized by malignant plasma cell proliferation in the bone marrow. Recent treatment advances have significantly improved patient outcomes associated with MM.In this study, we aimed to develop comprehensive, evidence-based guidelines for the diagnosis, prognosis, and treat‑ ment of MM. We identified 12 key clinical questions essential for MM management, guiding the extensive literature review and meta-analysis of the study. Our guidelines provide evidence-based recommendations by integrating patient preferences with survey data. These recommendations include current and emerging diagnostic tools, thera‑ peutic agents, and treatment strategies. By prioritizing a patient-centered approach and rigorous data analysis, these guidelines were developed to enhance MM management, both in Korea and globally.

Background: Flow cytometric immunophenotyping of hematolymphoid neoplasms (FCIHLN) is essential for diagnosis, classification, and minimal residual disease (MRD) monitoring. FCI-HLN is typically performed using in-house protocols, raising the need for standardization. Therefore, we surveyed the current status of FCI-HLN in Korea to obtain fundamental data for quality improvement and standardization. Methods: Eight university hospitals actively conducting FCI-HLN participated in our survey.We analyzed responses to a questionnaire that included inquiries regarding test items, reagent antibodies (RAs), fluorophores, sample amounts (SAs), reagent antibody amounts (RAAs), acquisition cell number (ACN), isotype control (IC) usage, positiveegative criteria, and reporting. Results: Most hospitals used acute HLN, chronic HLN, plasma cell neoplasm (PCN), and MRD panels. The numbers of RAs were heterogeneous, with a maximum of 32, 26, 12, 14, and 10 antibodies used for acute HLN, chronic HLN, PCN, ALL-MRD, and multiple myeloma-MRD, respectively. The number of fluorophores ranged from 4 to 10. RAs, SAs, RAAs, and ACN were diverse. Most hospitals used a positive criterion of 20%, whereas one used 10% for acute and chronic HLN panels. Five hospitals used ICs for the negative criterion. Positiveegative assignments, percentages, and general opinions were commonly reported. In MRD reporting, the limit of detection and lower limit of quantification were included. Conclusions This is the first comprehensive study on the current status of FCI-HLN in Korea, confirming the high heterogeneity and complexity of FCI-HLN practices. Standardization of FCI-HLN is urgently needed. The findings provide a reference for establishing standard FCI-HLN guidelines.

We would like to introduce domestic subscribers of the Korean Journal of Blood Transfusion to the important aspects to be considered while selecting a reference allele and reporting a new allele candidate. ABO*A1.02 has only a single nucleotide substitution of c.467C＞T in ABO*A1.01, and when ABO*A1.01 is used as the reference allele, the ABO*AW.10 allele should be marked as having both c.467C＞T and c.784G＞A variants. Unfortunately, it has not been modified as such in the ISBT database. For this reason, in the journal Transfusion (2020), the official journal of the Association for the Advancement of Blood Biotherapies, there was a report of a new allele with c.467C＞T and c.784G＞A variants. Cases of ABO*AW.10 allele with a weak A phenotype are not uncommon in Koreans, and it is necessary to accurately mark the reference allele. The blood type A reference allele of the International Society of Blood Transfusion (ISBT) database currently used for ABO alleles reporting is based on ABO*A1.01. Therefore, it should be considered that the ABO*AW.10 allele has both the c.467C＞T and c.784G＞A variants together.

The Korean Journal of Blood Transfusion (KJBT) stands as a prominent publication in the field of transfusion medicine, playing a pivotal role in advancing both national blood management projects and clinical explorations.In three years (2021∼2023) KJBT has disseminated 60 articles. During this period, five new article types (opinion, illustrated, mini-review, protocol, and annual report) have been introduced, and a new version of the online submission system has been implemented. The articles in KJBT have also been used as a valuable reference source for the first textbook on transfusion medicine published by the Korean Society of Blood Transfusion in 2023. With the ongoing efforts of the editorial team to provide better services to authors and readers, coupled with the sustained interest and passion of all the members, we hope that KJBT will continue to contribute to the advancement of domestic transfusion medicine research and the national blood program.

Transfusion support for hematopoietic stem cell transplantation (HSCT) is an essential part of supportive care, and compatible blood should be transfused into recipients. As leukocyte antigen (HLA) matching is considered first and as the blood group does not impede HSCT, major, minor, bidirectional, and RhD incompatibilities occur that might hinder transfusion and cause adverse events. Leukocyte reduction in blood products is frequently used, and irradiation should be performed for blood products, except for plasma. To mitigate incompatibility and adverse events, local transfusion guidelines, hospital transfusion committees, and patient management should be considered.

The Landsteiner–Wiener (LW) antigen is a type of red blood cell antigen. Anti-LW appears in various situations, including alloantibodies, autoantibodies, and even transiently occurring antibodies. Anti-LW has similar characteristics to anti-D, so it can interfere with interpreting pre-transfusion tests and finding compatible blood. This paper introduces three cases in whom anti-LW was detected through antibody identification tests. All three cases were examined using the column agglutination technique with ID-DiaPanel (Bio-Rad, Hercules, CA, USA) on a LISS/Coombs card, ID-DiaPanel p (Bio-Rad) on a NaCl/Enzyme card, and ID-DiaPanel (Bio-Rad) on a LISS/Coombs card using red blood cells treated with dithiothreitol. The auto-control test, direct antiglobulin test, and umbilical cord blood test were also performed. In all three cases, the reaction with D-positive panel cells was stronger than that with the D-negative panel cells, and two of them showed a pan-agglutinated reaction in ID-DiaPanel p (Bio-Rad) with NaCl/Enzyme card. They were reported as anti-LW, and as in these cases, anti-LW can occur under a range of conditions and interfere with proper transfusion. Therefore, it is important to identify anti-LW accurately, and if anti-LW is present, the transfusion of D-negative ABO matched blood should be recommended because of the low expression of the LW-antigen. On the other hand, D-positive blood is not a contraindication when an urgent transfusion is needed.

We used serial rectal swabs to investigate the amount and duration of virus secretion through the gastrointestinal tract and assessed the association between fecal shedding and gastrointestinal symptoms and to clarify the clinical usefulness testing rectal swabs.We enrolled ten adult patients hospitalized with symptomatic coronavirus disease 2019 (COVID-19). Respiratory and stool specimens were collected by physicians. The presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was confirmed using real-time reverse-transcription polymerase chain reaction. All ten patients had respiratory symptoms, six had diarrhea, and seven were positive for SARS-CoV-2 on rectal swabs. The viral loads in the respiratory specimens was higher than those in the rectal specimens, and no rectal specimens were positive after the respiratory specimens became negative. There was no association between gastrointestinal symptoms, pneumonia, severity, and rectal viral load. Rectal swabs may play a role in detecting SARS-CoV-2 in individuals with suspected COVID-19, regardless of gastrointestinal symptoms.