Immature Platelet Fraction as a Predictor of Platelet Recovery Following Hematopoietic Progenitor Cell Transplantation

Abstract

The immature platelet fraction (IPF) as determined by the Sysmex XE-2100 is a rapid automated measure of the least mature component of the platelet population and is thought to correlate with thrombopoietic activity of the marrow. We investigated the ability of IPF to predict platelet recovery following hematopoietic progenitor cell (HPC) transplantation. IPF was compared to standard parameters of hematopoietic recovery, including the immature reticulocyte fraction (IRF), an early predictor of recovery. Fifty patients undergoing peripheral blood HPC transplantation (38 autologous and 12 allogeneic) were followed daily for 11 to 28 days after transplantation with measurement of IPF, IRF, absolute neutrophil counts (ANC) and platelet counts. Mean days to recovery for IPF was 3.1 days less than for platelet count (P <.0001), 3.8 days less than for ANC (P <.0001), and 0.6 days less than for IRF (P = .0477). IPF recovered at least 1 day prior to platelet count in 79% (38 of 48) of patients, and was followed by platelet count recovery within 1 to 12 days (mean, 4.1 days). When autologous and allogeneic patient groups were analyzed separately, IPF recovered significantly earlier than platelet count and ANC in both groups (P <.0001). Thrombopoietin (TPO) levels in 5 patients receiving transplants correlated with IPF; however, this appeared to be secondary to an inverse correlation of both TPO and IPF with platelet count. IPF is comparable to IRF as one of the earliest predictors of hematopoietic recovery following peripheral blood HPC transplantation. IPF could potentially be useful as a predictor of platelet recovery in other bone marrow failure syndromes.

Immature Platelet Fraction: Establishment of a Reference Interval and Diagnostic Measure for Thrombocytopenia

“…The previously reported reference interval using the Sysmex XE-2100 for healthy adults is between 0.4% and 10% [1,9,[22][23][24][25][26][27]. The limitations of these reported reference intervals are: 1) small control groups, including less than 150 individuals, 2) incorrect application or lack of application of the CLSI guideline for determining reference intervals, and 3) exclusion of pediatric individuals in the control group.…”

“…The IPF% can be a useful parameter to estimate platelet recovery after peripheral blood stem cell transplant and chemotherapy, thereby reducing the number of unnecessary platelet transfusions. Following peripheral blood stem cell transplant in adults, the IPF% value rises 1-2 days prior to the increment in platelet count [23,25]. Saigo et al [30] observed platelet recovery within 3-7 days after the day of peak IPF% in pediatric patients with various malignant disorders after chemotherapy.…”

The Platelet Activity After Clopidogrel Termination (PACT) Study

“…[25][26][27] The Sysmex XE2100 identifies the IPF using a combination of a proprietary fluorescent RNA stain (which preferentially binds young platelets) and light scatter characteristics. [25][26][27] The immature platelet count was derived from the platelet count (measured in the XE2100) and the IPF %.…”

“…This question was addressed in the present study by direct measurement of the number of circulating new platelets (by the IPF in a Sysmex XE-2100, which is based on the higher messenger RNA content of young compared with old platelets [25][26][27] ). We demonstrated that discontinuation of clopidogrel did not result in the release of young platelets ( Figure 6).…”

Platelet analysis in laboratory hematology

“…This is why the devices currently available, despite claims to the contrary, have a poor specificity for "reticulated" platelets even if the addition of RNAse is used as evidence and somewhat reduces the signal. Therefore, the expectations in the follow-up studies to the original publications with manual measurement on the flow cytometer [6][7][8][9][10][11][12] have not been met, or only partially, on routine equipment with a reticulocyte channel [13][14][15][16][17][18], since the Spearman correlation coefficients are only at about 0.6. This clinically valuable parameter of the increased premature platelet release has therefore rarely been incorporated into clinical decisions in the differential diagnosis of thrombocytopenia.…”