Immature Platelet Research Articles

Immature Platelet Fraction in Rheumatoid Arthritis with Interstitial Lung Disease.

Platelets have an effect on the hemostatic defense of the lung. Immature platelet fractions (iPF) reflects the number of young platelets containing ribonucleic acid in the circulation and real-time production. Information about their roles in rheumatic diseases is limited and there are no studies on iPF in RA with interstitial lung disease (ILD). Our aim is to investigate the association between the iPF level and occurrence of ILD in RA and the correlation of iPF with disease activity in general or only in RA with ILD. The study included 50 RA patients without ILD, 33 RA patients with ILD, and 30 healthy controls. Demographic data, Disease Activity Score 28 (DAS28), autoantibodies, and iPF were evaluated. ILD was diagnosed by using high-resolution computed tomography with clinical findings and chest X-ray. The samples were analyzed for complete blood count with platelet indices included, on Mindray BC-6800 hematology analyzer, Hamburg, Germany. iPF levels were higher in RA patients with ILD compared to healthy controls and RA patients without ILD. A weakly positive correlation between DAS28 with iPF was found in all RA patients. iPF levels were found as 2.85 to detect ILD with 66.7% sensitivity and 65% specificity. Our results showed that the iPF was detected higher in RA with ILD compared to RA without ILD. iPF, a routine cheap and easy test during hemogram, can provide important information in terms of disease activity and lung involvement in RA.

Immature Platelet Fraction and Thrombin Generation: Preeclampsia Biomarkers.

Preeclampsia, a human pregnancy syndrome, is characterized by elevated blood pressure and proteinuria after the 20th week of gestation. Its etiology remains unknown, and its pathophysiological mechanisms are related to placental hypoperfusion, endothelial dysfunction, inflammation, and coagulation cascade activation. Recently, the role of the complement system has been considered. This syndrome is one of the main causes of maternal and fetal mortality and morbidity. This article discusses the hypothesis of preeclampsia being triggered by the occurrence of inadequate implantation of the syncytiotrophoblast, associated with bleeding during the first stage of pregnancy and with augmented thrombin generation. Thrombin activates platelets, increasing the release of antiangiogenic factors and activating the complement system, inducing the membrane attack complex (C5b9). Immature platelet fraction and thrombin generation may be possible blood biomarkers to help the early diagnosis of preeclampsia.

Transthyretin, Immature Platelet Fraction, and Mean Platelet Volume in Normotensive and Preeclampsia Pregnancy

BACKGROUND: Transthyretin protein experiences misfolding and aggregation in preeclampsia due to placental ischemia and inflammation. Placental endothelial damage occurring in preeclampsia stimulates the production of larger young platelets in the bone marrow and can be reflected by an increase in the immature platelet fraction (IPF) and mean platelet volume (MPV). Since the change in these markers in preeclampsia remains controversial, this study was conducted to analyze the differences in levels of transthyretin, IPF, and MPV as easily accessible markers in normotensive and preeclampsia pregnancies.METHODS: Total subjects included in this study were 32 normotensive and 26 preeclampsia pregnant woman. The measurement of serum transthyretin level was using enzyme-linked immunosorbent assay (ELISA) method. Meanwhile, IPF and MPV levels were measured by using a hematology analyzer with flowcytometry method. Data was statistically analyzed using unpaired T-test and Mann-Whitney, with significancy of p<0.05.RESULTS: Median value of transthyretin in normotensive and preeclampsia pregnancy were 11 (6-30) mg/dL and 9 (5-18) mg/dL. The mean value of IPF in normotensive and preeclampsia pregnancy were 4.56±2.19% and 6.33±2.99%. Mean value of MPV in normotensive and preeclampsia pregnancy were 10.41±0.76 fL and 11.32±1.2 fL. There were significant differences in levels of transthyretin, IPF, and MPV between normotensive and preeclampsia pregnancies (p=0.008, p=0.017, and p=0.002, respectively).CONCLUSION: There are significant differences in transthyretin levels, IPF, and MPV values in normotensive and preeclampsia pregnancies. Therefore, serum transthyretin, IPF, and MPV can be developed as affordable parameters for the diagnosis of preeclampsia.KEYWORDS: preeclampsia, transthyretin, IPF, MPV

Cytoreductive treatment and association with platelet function and maturity in patients with essential thrombocythaemia.

SummaryPatients with essential thrombocythaemia (ET) have an increased risk of thromboembolic events, which may differ according to different cytoreductive drugs. We investigated the effect of cytoreductive treatment on platelet function and turnover in ET patients. Blood samples were obtained at 1 and 24 h after aspirin intake. Platelet function was evaluated by platelet aggregation and flow cytometry. Platelet turnover was assessed by immature platelet count, immature platelet fraction (IPF) and mean platelet volume (MPV). A total of 47 ET patients were included and grouped into 21 patients not receiving cytoreductive treatment, 15 patients receiving hydroxycarbamide and 11 patients receiving pegylated interferon alpha (peg‐IFN). Patients receiving peg‐IFN had significantly higher IPF and MPV than the other ET groups. Patients not receiving cytoreductive treatment had significantly higher platelet aggregation 24 h after aspirin intake than the other ET groups (p‐values from 0.03 to 0.0002). Patients receiving hydroxycarbamide had significantly higher expression of platelet granule makers, P‐selectin and CD63, than patients receiving peg‐IFN (p‐values ≤0.003). Cytoreduction provides more consistent platelet inhibition compared with no cytoreductive treatment. Moreover, peg‐IFN provides superior inhibition of platelet activation markers than hydroxycarbamide, which in part may explain differences in risk of thromboembolic events in ET patients.

Changes in Platelet Function in Preterm Newborns with Prematurity Related Morbidities.

Platelet indices represent useful biomarkers to express the thromboembolic status, inflammatory response, and oxidative stress in preterm newborns. Our study presented platelet count and function changes in prematurity-related morbidities such as respiratory distress syndrome, intraventricular bleeding, and anemia of prematurity in preterm newborn cases reported to healthy full-term newborns by flow cytometry and hematological methods. The platelet volume represents the average size of platelets in the blood samples, showing the significantly increased values in preterm newborns compared with healthy full-term newborns due to increasing activated platelet production. Flow cytometric analysis of immature platelet fractions (IPF) made using thiazole orange staining to detect their mRNA content and a glycoprotein (anti-GPIIIa) antibody for platelet gating. CD61-TO expression from premature newborns was significantly lower compared to healthy full-term neonates. Preterm newborn cases with respiratory distress syndrome and a need for respiratory support (RDS+) were characterized by a significantly increased platelet volume and a decreased immature platelet fraction reported in RDS− cases. Evaluating the platelet function in the newborn is difficult because the laboratory methodologies work with small quantities of newborn blood samples. The immature platelet fractions and platelet volume promise to be diagnostic biomarkers for diseases.

Comparison of thrombocytopenia between patients with non-alcoholic fatty liver disease and those with hepatitis C virus-related chronic liver disease.

Thrombocytopenia is widely recognized as a simple surrogate marker of liver fibrosis in non-alcoholic fatty liver disease (NAFLD). Thrombocytopenia of NAFLD has not been compared with that of hepatitis C virus-related chronic liver disease (CLD-C). Here, we examined whether there is any difference in the platelet counts between patients with NAFLD and CLD-C and investigated the underlying mechanisms. A total of 760 biopsy-confirmed NAFLD and 1171 CLD-C patients were enrolled. After stratification according to the liver fibrosis stage, platelet counts between NAFLD and CLD-C patients were compared. The platelet count, spleen size, serum albumin level, serum thrombopoietin level, and immature platelet fraction (IPF) value were also compared after covariate adjustment using propensity score (PS) matching. The median platelet counts (×104 /μL) of NAFLD and CLD-C patients were 20.2 and 18.7 (p=2.4×10-5 ) in F1; 20.0 and 14.5 (p=2.1×10-12 ) in F2; 16.9 and 12.3 (p=8.1×10-10 ) in F3; and 11.1 and 8.1 (p=0.02) in F4, respectively. In the F3 group, NAFLD patients had a significantly higher platelet count and significantly smaller spleen volume than CLD-C patients. Although the serum thrombopoietin levels were comparable between NAFLD and CLD-C patients, the IPF value of NAFLD patients was significantly higher than that of CLD-C patients. NAFLD patients had a significantly higher platelet count than CLD-C patients following stratification according to the liver fibrosis stage. The milder hypersplenism and higher platelet production in NAFLD than CLD-C may have contributed to this difference.

Immature Platelet Fraction and Its Kinetics in Neonates.

Thrombocytopenia is a common abnormality encountered in the neonatal period, and immature platelet fraction (IPF) may be an informative indicator of thrombopoiesis; however, data on IPF in neonates are scarce. To define reference intervals (RIs) and factors affecting IPF in neonates, we measured the IPF of 533 consecutive neonates. With a multiple regression analysis of 330 newborns with normal platelet counts at birth, premature delivery, neonatal asphyxia, intrauterine infection, chromosomal abnormalities, and respiratory disorders were identified as independent factors for IPF%. The RIs of IPF% and absolute IPF value in neonates were determined to be 1.3% to 5.7% and 3.2 to 14.5×10 9 /L, respectively. On day 14 after birth, IPF% increased to twice the value at birth and thereafter returned to the previous value on day 28. Reticulocyte counts, in contrast, were the lowest at day 14. IPF% was increased in 16 thrombocytopenic patients with various clinical conditions, especially those with immune-mediated thrombocytopenia. IPF in neonates may be evaluated essentially based on the same RIs as in adults, although some precautions must be taken when evaluating IPF in neonates in the first 2 weeks of life. IPF may be useful for evaluating thrombopoiesis and thrombocytopenia in neonates.

Comparison of absolute immature platelet count to the PLASMIC score at presentation in predicting ADAMTS13 deficiency in suspected thrombotic thrombocytopenic purpura

IntroductionThrombotic thrombocytopenic purpura (TTP) demands rapid initiation of therapeutic plasma exchange to avoid severe complications associated with it. ADAMTS13 activity <10% defines TTP, however, this is a send-out test at most institutions. We have previously reported our experience looking at absolute immature platelet counts (A-IPC) in TTP patients. Thus, we compared A-IPC on admission to the PLASMIC score to predict ADAMTS13 deficiency. Materials and methodsOf seventy-two patients identified, 52 met inclusion criteria. All patients were suspected of new-onset TTP and had A-IPC on admission. Of these patients, 25/52 were later shown to have ADAMTS13 <10%, defined as TTP group, and 27/52 had ADAMTS13 >10% and are henceforth classified as non-TTP. ResultsPatients with TTP were found to have A-IPC below reference range (<1.5 × 109/L) and responded to therapy as shown by fold-increases in A-IPC (p < 0.0001), neither seen in non-TTP patients. A-IPC had a significant correlation with ADAMTS13 deficiency (p = 0.0001) with high sensitivity, specificity, positive and negative predictive values. Comparison of A-IPC to PLASMIC score indicated that the former identified all TTP patients compared to PLASMIC score even in patients obtaining scores of 4 and 5. Finally, Receiver Operating Characteristic curves showed A-IPC had area under the curve of 0.986. ConclusionsA-IPC below reference range and A-IPC fold-increases were only observed in TTP patients. There was strong association between A-IPC and ADAMTS13 deficiency and A-IPC predicted patients with ADAMTS13 deficiency. Future larger studies are needed to determine ways to apply findings in suspected TTP patients.

Thrombocytopenia and insufficient thrombopoietin production in human small-for-gestational-age infants

BackgroundSmall-for-gestational-age (SGA) infants are at increased risk for transient thrombocytopenia. The aim of this study was to determine whether thrombocytopenia in human SGA infants is due to insufficient thrombopoietin (TPO) production.MethodsA prospective study of 202 infants with gestational age less than 37 weeks was conducted; 30 of them were SGA infants, and 172 were non-SGA infants. Thrombocytopenia was seen in 17 of 30 SGA infants and 40 of 172 non-SGA infants.ResultsPlatelet counts were significantly lower in the SGA group than in the non-SGA group at the time of the lowest platelet count within 72 h of birth. The platelet count and immature platelet fraction (IPF) were negatively correlated in non-SGA infants, but not in SGA infants. In addition, the platelet count and TPO were negatively correlated in non-SGA infants. IPF and TPO were significantly lower in SGA than in non-SGA infants with thrombocytopenia.ConclusionIPF increased with thrombocytopenia to promote platelet production in non-SGA infants due to increasing TPO, but not in SGA infants. This study found an association between insufficient TPO production and thrombocytopenia in SGA infants. In addition, this study is important for understanding the etiology of thrombocytopenia in SGA infants.ImpactThe immature platelet fraction was low, and serum thrombopoietin was not increased in small-for-gestational-age (SGA) infants with thrombocytopenia.Thrombocytopenia in SGA infants is due to insufficient thrombopoietin production.This study is important for understanding the etiology of thrombocytopenia in SGA infants.

M282 Immature platelet fraction and mean platelet volume in differentiating acute coronary syndrome types

M282 Immature platelet fraction and mean platelet volume in differentiating acute coronary syndrome types

T087 Research of immature platelets and aggregation in cardiological practice

T087 Research of immature platelets and aggregation in cardiological practice

The role of immature platelet count and immature platelet fraction in determining the need for transfusion in patients undergoing CABG.

Platelet dysfunction has been shown to play a role in postoperative bleeding, however it is not clear whether immature platelets (IP) can induce appropriate homeostasis to prevent excessive bleeding in patients undergoing coronary artery bypass grafting (CABG). The aim of this study was to evaluate the postoperative change in IP count (IPC), IP fraction (IPF) and mean platelet volume (MPV), and to examine their relationship with postoperative bleeding and blood transfusion. One hundred and forty-nine consecutive patients undergoing elective CABG were included in this prospective study. All CABGs were performed by the same surgical team in a standardised method, utilising the on-pump technique. IPC, MPV and IPF were measured pre-operatively, after the completion of surgery, and at the postoperative first, third and fifth days. The primary outcome measure of this study was whether the need for transfusion was associated with IP, IPF, MPV and platelet count. There was a significant decrease of 7.77% in IPC on the day of the operation. Pre-operative IPC and IPF were correlated with postoperative drainage (p < 0.001), intraoperative blood transfusion (p < 0.001) and intensive care unit blood transfusion (p < 0.001). Pre-operative haemoglobin levels were significantly correlated with length of hospital stay. However, neither pre-operative IPC nor IPF were associated with length of hospital stay. Postoperative IPC was however associated with the length of hospital and intensive care unit stay (p = 0.008 and p = 0.009, respectively). Pre-operative IPC and IPF were significantly correlated with postoperative drainage and blood transfusion frequency. In patients undergoing CABG, these can be seen as serious guiding parameters in the estimation of postoperative bleeding.

Diagnostic value of platelet indices in COVID 19 infection: a case-control study from a single tertiary care center

IntroductionPlatelets are not only involved in hemostasis and coagulation, but play a significant role in innate immunity and inflammatory response. Excess production of cytokines and acute phase reactants affect megakaryopoiesis resulting in the release of immature platelets from the bone marrow altering platelet indices.AimTo study platelet indices in RT-PCR-proven COVID patients and non-COVID patients. MethodsA case-control study was conducted on 199 COVID-19 patients and 198 normal individuals. Blood samples were analyzed in an automated hematology analyzer. The platelet indices like platelet count, mean platelet volume (MPV), platelet distribution width (PDW), platelet large cell count (PLCC), and platelet large cell ratio (P-LCR) were compared among two groups.ResultsPlatelet count in COVID-19 patients were significantly low (p<0.01) compared to controls, and a significant number of COVID-19 patients had thrombocytopenia. Plateletcrit (PCT) was also significantly decreased in COVID-19 patients compared to non-COVID individuals. MPV, PDW, and PLCR were significantly (p<0.05) high in COVID-19 patients in comparison to controls, but was not significantly raised in a large number of cases. In contrast, there were no significant differences in platelet large cell count (PLCC) values between COVID-19 cases and non-COVID-19 controls.ConclusionPlatelet indices like platelet count, PCT, MPV, PDW, and P-LCR are significantly altered in COVID-19 infection and thereby can be used as biomarkers in COVID-19. Further research is needed to find if these simple, cost-effective parameters can be used to predict the severity and prognosis in COVID-19 infection.

Src-related thrombocytopenia: a fine line between a megakaryocyte dysfunction and an immune-mediated disease

AbstractSrc-related thrombocytopenia (SRC-RT) is a rare autosomal dominant, inherited platelet disorder resulting from the p.E527K heterozygous germline gain-of-function variant of Src. To date, genetic diagnosis of the disease has only been reported in 7 patients from 3 unrelated families. The clinical features ranged from isolated thrombocytopenia to complex syndromic manifestations characterized by thrombocytopenia, bleeding, myelofibrosis, splenomegaly, and bone disease. We report a new 3-generation kindred with the Src p.E527K variant. Patients presented with rather variable platelet counts (38-139 × 109/L), mildly impaired platelet function, >15% immature platelet fraction, and with a significant proportion of large-giant platelets. Four adults from the family were diagnosed with immune thrombocytopenia (ITP) and underwent splenectomy, achieving sustained platelet counts >75 × 109/L for several years; increases in platelet counts were also observed after corticosteroid therapy. Four of 7 Src p.E527K variant carriers showed immune defects and recurrent infections. In addition, a range of neurological symptoms, from specific language impairment to epilepsy, was seen in some family members. Patient platelets exhibited constitutive Src, Bruton tyrosine kinase, and phospholipase Cγ2 activation, and after stimulating CD19 cells by crosslinking surface immunoglobulin M, phosphorylated extracellular signal-regulated kinase (ERK) was significantly increased in B cells from individuals carrying the Src p.E527K substitution. In summary, in addition to causing impaired platelet production, SRC-RT may associate immune dysregulation and increased platelet consumption. In families in whom several members are responsive to ITP-directed therapies, an underlying Src p.E527K variant should be excluded.

Routine and Advanced Laboratory Tests for Hemostasis Disorders in COVID-19 Patients: A Prospective Cohort Study.

Background: Thrombosis is frequent during COVID-19 disease, and thus, identifying predictive factors of hemostasis associated with a poor prognosis is of interest. The objective was to explore coagulation disorders as early predictors of worsening critical conditions in the intensive care unit (ICU) using routine and more advanced explorations. Materials: Blood samples within 24 h of ICU admission for viscoelastic point-of-care testing, (VET), advanced laboratory tests: absolute immature platelet count (A-IPC), von Willebrand-GPIb activity (vWF-GpIb), prothrombin fragments 1 + 2 (F1 + 2), and the thrombin generation assay (TGA) were used. An association with worse outcomes was explored using univariable and multivariable analyses. Worsening was defined as death or the need for organ support. Results: An amount of 85 patients with 33 in critical condition were included. A-IPC were lower in worsening patients (9.6 [6.4–12.5] vs. 12.3 [8.3–20.7], p = 0.02) while fibrinogen (6.9 [6.1–7.7] vs. 6.2 [5.4–6.9], p = 0.03), vWF-GpIb (286 [265–389] vs. 268 [216–326], p = 0.03) and F1 + 2 (226 [151–578] vs. 155 [129–248], p = 0.01) were higher. There was no difference observed for D-dimer, TGA or VET. SAPS-II and A-IPC were independently associated with worsening (OR = 1.11 [1.06–1.17] and OR = 0.47 [0.25–0.76] respectively). The association of a SAPS-II ≥ 33 and an A-IPC ≤ 12.6 G/L predicted the worsening of patients (sensitivity 58%, specificity 89%). Conclusions: Immature platelets are early predictors of worsening in severe COVID-19 patients, suggesting a key role of thrombopoiesis in the adaption of an organism to SARS-CoV-2 infection.

Higher body mass index raises immature platelet count: potential contribution to obesity-related thrombosis

Higher body mass index (BMI) is a risk factor for thrombosis. Platelets are essential for hemostasis but contribute to thrombosis when activated pathologically. We hypothesized that higher BMI leads to changes in platelet characteristics, thereby increasing thrombotic risk. The effect of BMI on platelet traits (measured by Sysmex) was explored in 33 388 UK blood donors (INTERVAL study). Linear regression showed that higher BMI was positively associated with greater plateletcrit (PCT), platelet count (PLT), immature platelet count (IPC), and side fluorescence (SFL, a measure of mRNA content used to derive IPC). Mendelian randomization (MR), applied to estimate a causal effect with BMI proxied by a genetic risk score, provided causal estimates for a positive effect of BMI on both SFL and IPC, but there was little evidence for a causal effect of BMI on PCT or PLT. Follow-up analyses explored the functional relevance of platelet characteristics in a pre-operative cardiac cohort (COPTIC). Linear regression provided observational evidence for a positive association between IPC and agonist-induced whole blood platelet aggregation. Results indicate that higher BMI raises the number of immature platelets, which is associated with greater whole blood platelet aggregation in a cardiac cohort. Higher IPC could therefore contribute to obesity-related thrombosis.

Association of whole blood microRNA expression with platelet function and turnover in patients with coronary artery disease

IntroductionThe risk of recurrent cardiovascular events in patients with coronary artery disease (CAD) is determined by multiple factors including platelet function and turnover. MicroRNAs (miRs) may regulate both platelet function and turnover. We aimed to identify candidate miRs associating with platelet function and turnover in a cohort of stable CAD patients. Furthermore, we retrieved information on binding targets of the candidate miRs to obtain a more comprehensive biological insight into miR regulation of platelet function and turnover. MethodsBased on existing literature and a pilot study, we identified nine candidate miRs. Subsequently, we investigated the expression of the candidate miRs in whole blood and their relation to platelet function and turnover in 749 CAD patients. Platelet function was analysed using impedance aggregometry, optical aggregometry and serum thromboxane B2 measurements. Platelet turnover markers (immature platelet count, immature platelet fraction and mean platelet volume) were measured using monochromatic automated flow cytometry. ResultsExpression of miR-93-5p, miR-126-3p, miR-150-5p, miR-423-3p and miR-1180-3p showed negative correlations with platelet function (p-values from <0.0001 to 0.0006, rho from −0.13 to −0.36). In addition, expression of miR-423-3p showed negative correlation with platelet turnover markers (p-values from 0.001 to 0.004, rho from −0.11 to −0.12). ConclusionsWe identified several novel miRs that may regulate platelet function and turnover, thereby contributing to the increased risk of recurrent cardiovascular events in CAD patients.

Impact of high platelet turnover on the platelet transcriptome: Results from platelet RNA-sequencing in patients with sepsis.

Sepsis is associated with high platelet turnover and elevated levels of immature platelets. Changes in the platelet transcriptome and the specific impact of immature platelets on the platelet transcriptome remain unclear. Thus, this study sought to address whether and how elevated levels of immature platelets affect the platelet transcriptome in patients with sepsis. Blood samples were obtained from patients with sepsis requiring vasopressor therapy (n = 8) and from a control group of patients with stable coronary artery disease and otherwise similar demographic characteristics (n = 8). Immature platelet fraction (IPF) was determined on a Sysmex XE 2100 analyser and platelet function was tested by impedance aggregometry. RNA from leukocyte-depleted platelets was used for transcriptome analysis by Next Generation Sequencing integrating the use of unique molecular identifiers. IPF (median [interquartile range]) was significantly elevated in sepsis patients (6.4 [5.3-8.7] % vs. 3.6 [2.6-4.6] %, p = 0.005). Platelet function testing revealed no differences in adenosine diphosphate- or thrombin receptor activating peptide-induced platelet aggregation between control and sepsis patients. Putative circular RNA transcripts were decreased in platelets from septic patients. Leukocyte contamination defined by CD45 abundance levels in RNA-sequencing was absent in both groups. Principal component analysis of transcripts showed only partial overlap of clustering with IPF levels. RNA sequencing showed up-regulation of 524 and down-regulation of 118 genes in platelets from sepsis patients compared to controls. Upregulated genes were mostly related to catabolic processes and protein translation. Comparison to published platelet transcriptomes showed a large overlap of changes observed in sepsis and COVID-19 but not with reticulated platelets from healthy donors. Patients with sepsis appear to have a less degraded platelet transcriptome as indicated by increased levels of immature platelets and decreased levels of putative circular RNA transcripts. The present data suggests that increased protein translation is a characteristic mechanism of systemic inflammation.

Analysis of preplatelets and their barbell platelet derivatives by imaging flow cytometry

AbstractCirculating large “preplatelets” undergo fission via barbell platelet intermediates into two smaller, mature platelets. In this study, we determine whether preplatelets and/or barbells are equivalent to reticulated/immature platelets by using ImageStream flow cytometry and super-resolution microscopy. Immature platelets, preplatelets, and barbells were quantified in healthy and thrombocytopenic mice, healthy human volunteers, and patients with immune thrombocytopenia or undergoing chemotherapy. Preplatelets and barbells were 1.9% ± 0.18%/1.7% ± 0.48% (n = 6) and 3.3% ± 1.6%/0.5% ± 0.27% (n = 12) of total platelet counts in murine and human whole blood, respectively. Both preplatelets and barbells exhibited high expression of major histocompatibility complex class I with high thiazole orange and Mitotracker fluorescence. Tracking dye experiments confirmed that preplatelets transform into barbells and undergo fission ex vivo to increase platelet counts, with dependence on the cytoskeleton and normal mitochondrial respiration. Samples from antibody-induced thrombocytopenia in mice and patients with immune thrombocytopenia had increased levels of both preplatelets and barbells correlating with immature platelet levels. Furthermore, barbells were absent after chemotherapy in patients. In mice, in vivo biotinylation confirmed that barbells, but not all large platelets, were immature. This study demonstrates that a subpopulation of large platelets are immature preplatelets that can transform into barbells and undergo fission during maturation.

Evaluation of Immature Platelet Fraction in Patients with Fever and Thrombocytopenia and its Clinical Utility

Introduction: Thrombocytopenia is very common in dengue and other haematological disorders and the aetiology is multifactorial. Immature Platelet Fraction (IPF) is a novel parameter which is a measure of reticulated platelets and it reflects the rate of regeneration of platelets. Aim: To evaluate the relationship between the IPF and platelet recovery and the consistency of its expression. Materials and Methods: The present study was a retrospective observational study done at Institute of Pathology, Madras Medical College between November 2018 to December 2018. Total 37 patients having fever with thrombocytopenia in dengue and other haematological causes were included for analysis. The platelet count, IPF, Mean Platelet Volume (MPV), Platelet Distribution Width (PDW) and Plateletcrit (PCT) was evaluated at the time of admission and once in every 24 hours and plotted in excel spread sheet. Results: About 86.4% were recovered in 24 hours after attaining the peak, 89.1% showed recovery in 24-48 hours of the rise of the IPF compared to the previous value and 94.5% recovered within 24 hours after the fall in the IPF value. It was observed that 81.8% were recovered when the IPF value ≥10% within 24- 48 hours. IPF readings are able to appreciate even in low platelet count levels but the other platelet recovery parameters did not. Conclusion: IPF is a consistent and reliable marker which can be measured even when the platelet count is low and it also predicts the platelets recovery. It is a promising marker that helps in guiding the decision towards platelet transfusion.