BACKGROUND: Reticulocyte haemoglobin equivalent (RET-He) is a useful tool for evaluating recent iron usage irrespective of inflammatory status. This study aims to establish a reference for RET-He among Hong Kong healthy children under the age of 5 years and to investigate the association between RET-He and various blood parameters.
METHODS: A total of 946 children aged 2-48 months from July 2019 to December 2022 were recruited in this cross-sectional study. The RET-He and other haematological parameters were measured by the haematology analyser from Sysmex XN-9100/XN-1500. The ferritin test was performed with the electrochemiluminescence immunoassay. Interval 2.5th percentile to 97.5th percentile represented the normal RET-He ranges. Linear multiple regression analysis was performed to examine the relation between RET-He and various blood parameters. Receiver-operating characteristic curve analysis revealed the sensitivity and specificity of RET-He in identifying iron deficiency.
RESULTS: The RET-He in the study population was approximately normally distributed. The age-specific lower limit of RET-He ranges from 25.81 pg (25-36 months) to 27.15 pg (13-24 months). RET-He was found to be lower in the age group 2-6 months (mean=29.47 pg) and 7-12 months (mean=29.41 pg). Changes in RET-He and haemoglobin in relation to age were observed in both sexes (both p<0.001). RET-He was influenced by age, some red blood cell parameters and reticulocyte concentrations (all p<0.05). A cut-off value of RET-He ≤27.8 pg was determined for identifying iron deficiency.
CONCLUSIONS: RET-He levels varied with age, with a relatively lower level in infants than in other age groups. The value below the age-specific lower limit of the reference range of RET-He can be used as a limit for preliminary iron-deficiency screening.

OBJECTIVE: Women are more prone to iron deficiency (ID) anemia when pregnant. The diagnostic use of mean reticulocyte volume (MRV) in identifying ID anemia during pregnancy has not been thoroughly investigated. The objective of this study is to evaluate the effectiveness of MRV in diagnosing ID in pregnant women.
METHODS: Firstly, MRV of 20 healthy female volunteers (healthy group) was measured on specific days for one month. Subsequently, clinical data from 724 pregnant women were thoroughly examined. These women were divided into two groups: 282 with ID (research group) and 442 without ID (control group). Parameters such as MRV, reticulocyte hemoglobin equivalent (RHE), red blood cell volume distribution width-standard deviation (RDW-SD), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), hematocrit (HCT), reticulocyte count (RET), MRV/MCV ratio, and serum ferritin (SF) were analyzed and compared.
RESULTS: MRV remained consistent over a period of one month for 20 healthy individuals. In addition, there were significant differences in MRV, RHE, RDW-SD, MCV, MCH, MCHC, HCT, RET, and MRV/MCV between the research group and control group. The receiver operating characteristic (ROC) analysis showed that the areas under the curve (AUCs) for these measures were as follow: 0.840, 0.837, 0.676, 0.654, 0.639, 0.602, 0.571, 0.550, and 0.816, respectively. Ultimately, there was a substantial disparity in MRV prior to and following therapy with oral iron treatments.
CONCLUSIONS: In healthy women, MRV remains stable and is a reliable ID marker, which can be used to assess oral iron treatment effectiveness during pregnancy.

BACKGROUND: In light of prolonged hypoxia, children with cyanotic heart disase (CHD) are at a high risk of developing iron deficiency iron deficiency (ID) and iron deficiency anemia (IDA). Reticulocyte hemoglobin equivalent (Ret-He) is a novel and dependable indicator for assessing iron status. However, there has been no previous study regarding cut-off value in pediatric CHD group. The purpose of this study is to assess the role of Ret-He and to establish cut-off points in the diagnosis of iron deficiency and IDA in pediatric cyanotic heart disease.
METHODS: This study was conducted in two tertiary hospitals in Jakarta, Indonesia. 59 children with CHD, aged 3 months to 18 years, were enrolled consecutively. To determine iron status, hematological parameters (hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin) and biochemical parameters for iron status (serum ferritin, transferrin saturation) were analysed and compared to Ret-He levels. The receiver operating characteristic (ROC) analysis was performed for the Ret-He cut-off points for ID and IDA. Sensitivity, specificity, positive and negative predictive value were calculated for each cut-off point.
RESULTS: Normal iron status was identified in 27 (45.8%) subjects, ID in 8 (13.5%) subjects, and IDA 24 (40.7%) subjects. The ID cut-off value for Ret-He is 28.8 pg (sensitivity 75%, specificity 85.2%, PPV 60%, NPV 92%, and AUC 0.828) and the Ret-He cut-off point for IDA is 28.15 pg (sensitivity 75%, specificity 88.9%, PPV 85.7%, NPV 80%, and AUC 0.824). Hemoglobin should be used in conjunction with Ret-He. ID might be detected in this cohort with Ret-He 28.8 pg and hemoglobin > 16,5 g/dL. While Ret-He 28.15 pg or Ret-He 28.15-28.8 pg with hemoglobin 16.5 g/dL could be used to diagnose IDA.
CONCLUSIONS: The reticulocyte hemolgobin equivalent could be utilised as an iron status parameter in pediatric CHD, with a cut-off value of 28.8 pg for ID and 28.15 pg for IDA.

OBJECTIVE: ClFdA is a second-generation antineoplastic agent that has demonstrated significant anticancer activity, particularly against acute lymphoblastic leukemia and has been shown to have radiosensitizing activity. The aim of the study was to explore the genotoxic, cytotoxic and radiosensitizing effects of clofarabine (ClFdA) on bone marrow cells (BMCs), normoblasts and leukocytes of mice in vivo.
METHODS: Cytotoxicity was determined by the reduction in reticulocytes (RET), and genotoxicity was determined by the induction of micronucleated reticulocytes (MN-RET) in the peripheral blood and by DNA break induction in leukocytes determined by single-cell gel electrophoresis (SCGE). The radiosensitizing capacity of ClFdA was determined in leukocytes and BMCs by SCGE.
RESULTS: Two mechanisms of MN-RET induction were identified according to the antecedents, that could be due to inhibition of DNA synthesis and demethylation of G-C regions, and subsequent chromosome fragility. ClFdA cytotoxicity causes two contiguous peaks, an early peak that seems to inhibit MN-RET induction and a second peak that seems to be caused by ribonucleotide reductase (RR) and/or DNA synthesis inhibitions. ClFdA induced early DNA damage in noncycling leukocytes, and also radiosensitizes leukocytes immediately after treatment. ClFdA-ionizing radiation (IR) causes two time-dependent episodes of DNA damage, the latest after 80 min triggers a major breakage of DNA. In terms of the number of damaged cells, leukocytes and BMCs are similarly sensitive to ionizing radiation; BMCs are slightly more sensitive than leukocytes to ClFdA, but BMCs are doubly sensitive to combined treatment.
CONCLUSIONS: ClFdA causes early DNA damage and radiosensitivity in non-proliferating leukocytes, which rules out the most favored hypotheses of the participation of RR and DNA polymerase inhibition.

The oxygen-labile transcription factor called hypoxia-inducible factor (HIF) is responsible for the cellular and organismal adaptive response to reduced oxygen availability. Deregulation of HIF is associated with the pathogenesis of major human diseases including cardiovascular disease and cancer. Under normoxia, the HIFα subunit is hydroxylated on conserved proline residues within the oxygen-dependent degradation domain (ODD) that labels HIFα for proteasome-mediated degradation. Despite similar oxygen-dependent degradation machinery acting on HIF1α and HIF2α, these two paralogs have been shown to exhibit unique kinetics under hypoxia, which suggests that other regulatory processes may be at play. Here, we characterize the protease activity found in rabbit reticulocytes that specifically cleaves the ODD of HIF1α but not HIF2α. Notably, the cleavage product is observed irrespective of the oxygen-dependent prolyl-hydroxylation potential of HIF1α, suggesting independence from oxygen. HIF1α M561T substitution, which mimics an evolutionary substitution that occurred during the duplication and divergence of HIF1α and HIF2α, diminished the cleavage of HIF1α. Protease inhibitor screening suggests that cysteine proteases cathepsins L and B preferentially cleave HIF1αODD, thereby revealing an additional layer of differential HIF regulation.

BACKGROUND: Reticulocyte count and novel derived parameters provide insight into the effectiveness of erythropoiesis and may be useful tools in the classification and diagnosis of anemias. However, there is no standardisation, so we consider it necessary that each laboratory evaluates the parameters according to its own methodology and instrumentation and establishes its own reference ranges. Our aim was to establish the reference intervals (RIs) of reticulocyte profile provided by the Beckman Coulter DxH 900 haematological autoanalyzer in our reference population.
METHODS: One hundred and seventy-five healthy adults (18 to 62 years) were included. Subjects were collected from the blood donation centre of the Hospital Clínico San Carlos (Madrid, Spain) upon informed consent. Whole blood was collected and assayed for 14 haematological parameters on the Beckman Coulter DxH 900 analyzer in the haematology laboratory of the Clinical Analysis Department. RIs were established as per Clinical and Laboratory Standards Institute EP28-A3c guidelines using three different statistical approaches.
RESULTS: RIs estimated using the non-parametric method and the Harrell-Davis bootstrap method were very similar. RIs estimated by the robust method were narrower. Gender partitioning was required for two haematological parameters (low haemoglobin density (LHD) and microcytic anaemia factor (MAF)). The rest of the parameters did not need to be partitioned according to Lahti\'s method.
CONCLUSIONS: RIs have been established for 14 hematologic parameters of the reticulocyte profile for the Beckman Coulter DxH 900 haematology analyzer using a healthy cohort of adult subjects.

BACKGROUND: Endogenous and exogenous androgens increase circulating erythrocytes and hemoglobin but their effects on erythrocyte lifespan is not known.
OBJECTIVE: To investigate androgen effects on immature and mature erythrocyte lifespan in humans and mice using novel non-radioactive minimally invasive methods.
METHODS: Human erythrocyte lifespan was estimated using alveolar carbon monoxide concentration and blood hemoglobin in Levitt\'s formula in hypogonadal or transgender men before and up to 18 weeks after commencing testosterone (T) treatment. Erythrocyte lifespan was estimated in androgen receptor (AR) knockout and wild-type mice after T or dihydrotestosterone (DHT) treatment of intact females or orchidectomized males using in vivo biotin labelling of erythrocyte surface epitopes for reticulocytes (Ter119+CD71+) and two markers of erythrocytes (CD45-, Ter119+CD71-) monitoring their blood disappearance rate by flow cytometry.
RESULTS: Before treatment, hypogonadal and transgender men had marked reduction in erythrocyte lifespan compared with controls. T treatment increased erythrocyte lifespan at 6 weeks but returned to pre-treatment levels at 18 weeks while serum T and blood hemoglobin were increased by T treatment remaining elevated at 18-weeks. In mice T and DHT treatment had higher erythrocyte (but not reticulocyte) lifespan but neither orchidectomy nor AR inactivation significantly influenced erythrocyte or reticulocyte lifespan.
CONCLUSIONS: We conclude that hypogonadal men have reduced erythrocyte lifespan and acute androgen-induced increase in circulating erythrocyte lifespan may contribute to the well-known erythropoietic effects of androgens, but longer-term effects require further investigation to determine how much they contribute to androgen-induced increases in circulating hemoglobin.

Red blood cell (RBC) transfusion, limited by patient alloimmunization, demands accurate blood group typing. The Rh system requires specific attention due to the limitations of serological phenotyping methods. Although these have been compensated for by molecular biology solutions, some RhCE ambiguities remain unresolved. The RHCE mRNA length is compatible with full-length analysis and haplotype discrimination, but the RHCE mRNA analyses reported so far are based on reticulocyte isolation and molecular biology protocols that are fastidious to implement in a routine context. We aim to present the most efficient reticulocyte isolation method, combined with an RT-PCR sequencing protocol that embraces the phasing of all haplotype configurations and identification of any allele. Two protocols were tested for reticulocyte isolation based either on their size/density properties or on their specific antigenicity. We show that the reticulocyte sorting method by antigen specificity from EDTA blood samples collected up to 48 h before processing is the most efficient and that the combination of an RHCE-specific RT-PCR followed by RHCE allele-specific sequencing enables analysis of cDNA RHCE haplotypes. All samples analyzed show full concordance between RHCE phenotype and haplotype sequencing. Two samples from the immunohematology laboratory with ambiguous results were successfully analyzed and resolved, one of them displaying a novel RHCE allele (RHCE*03 c.340C>T).

UNASSIGNED: β-thalassemia is a condition characterized by reduced or absent synthesis of β-globin resulting from genetic mutations, leading to expanded and ineffective erythropoiesis. Mitoxantrone has been widely used clinically as an antitumor agent considering its ability to inhibit cell proliferation. However, its therapeutic effect on expanded and ineffective erythropoiesis in β-thalassemia is untested. We found that mitoxantrone decreased α-globin precipitates and ameliorated anemia, splenomegaly, and ineffective erythropoiesis in the HbbTh3/+ mouse model of β-thalassemia intermedia. The partially reversed ineffective erythropoiesis is a consequence of effects on autophagy as mitochondrial retention and protein levels of mTOR, P62, and LC3 in reticulocytes decreased in mitoxantrone-treated HbbTh3/+ mice. These data provide significant preclinical evidence for targeting autophagy as a novel therapeutic approach for β-thalassemia.

Monoclonal antibody biologics have significantly transformed the therapeutic landscape within the biopharmaceutical industry, partly due to the utilisation of discovery technologies such as the hybridoma method and phage display. While these established platforms have streamlined the development process to date, their reliance on cell transformation for antibody identification faces limitations related to library diversification and the constraints of host cell physiology. Cell-free systems like ribosome display offer a complementary approach, enabling antibody selection in a completely in vitro setting while harnessing enriched cellular molecular machinery. This review aims to provide an overview of the fundamental principles underlying the ribosome display method and its potential for advancing antibody discovery and development.