OC 33.2 - Assessment of platelet phenotype by immunofluorescence-microscopy on the peripheral blood smears in patients with myeloproliferative neoplasms

Monday, June 24, 2024

09:45 – 10:00 ICT

Room: Ballroom B3

Presenting Author(s)

Carlo Zaninetti, MD, PhD

Medical Doctor
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald, Germany
Greifswald, Mecklenburg-Vorpommern, Germany

Co-Author(s)

LV

Leonard Vater

PhD Student
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald
Greifswald, Mecklenburg-Vorpommern, Germany
LK

Lars Kaderali

Professor of Statistics
Institut für Bioinformatik, Universitätsmedizin Greifswald
Greifswald, Mecklenburg-Vorpommern, Germany
JF

Jessica Fuhrmann

Scientific assistant
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald
Greifswald, Mecklenburg-Vorpommern, Germany
JW

Jan Wesche

Scientific assistant
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald
Greifswald, Mecklenburg-Vorpommern, Germany
LS

Leonard Swensson

PhD Student
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald
Greifswald, Mecklenburg-Vorpommern, Germany
TS

Tina M. Schnöder

Researcher
Innere Medizin C, Universitätsmedizin Greifswald
Greifswald, Mecklenburg-Vorpommern, Germany
CC

Carl C. Crodel

Medical Doctor
Internal Medicine 2, University Hospital Jena, Jena, Germany
Jena, Thuringen, Germany
CF

Carmen Freyer

Scientific assistant
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald, Germany
Grei, Mecklenburg-Vorpommern, Germany
TT

Thomas Thiele

Professor of Transfusion Medicine
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald, Germany
Greifswald, Mecklenburg-Vorpommern, Germany
FH

Florian H. Heidel

Professor of Haematology
Innere Medizin C, Universitätsmedizin Greifswald
Hannover, Niedersachsen, Germany
Andreas Greinacher

Senior Professor
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald, Germany
Greifswald, Mecklenburg-Vorpommern, Germany

Background: Morphologic and functional platelet phenotype is frequently altered in myeloproliferative neoplasms (MPN). However, due to different methods and the heterogeneity of the patient population, results are difficult to compare. We have established an immunofluorescence-based method to phenotype platelets on the blood smear, which we had previously validated as a screening-tool for inherited platelet disorders.

Aims: To assess platelet phenotype by immunofluorescence-microscopy in a well-characterized cohort of patients diagnosed with MPN.

Methods: Blood smears were stained with 13 mouse and rabbit anti-human primary antibodies against markers of platelet structures. Investigators were primarily blinded for WHO diagnosis, mutational status or clinical phenotype. Changes of platelet structures were documented by a semiquantitative grading system. After unblinding, correlations between morphologic changes and clinical characteristics were assessed by Pearson’s chi-squared test with Yates’ continuity correction.

Results: We investigated 135 adult MPN patients (female, 55%): 36 (27%) with polycythaemia vera (PV), 31 (23%) with essential thrombocythemia (ET), 41 (30%) with primary myelofibrosis, and 8 (6%) with unclassifiable-MPN. 19 (14%) patients initially diagnosed with PV or ET had evolved into secondary myelofibrosis (SMF). We found a reduction of alpha-granule markers in 82 (61%) patients, and aggregates of the cytoskeletal protein non-muscular myosin IIA (NMMIIA) in the red blood cells (RBC) in 98 (73%). Alpha-granule deficiency significantly correlated with the presence of the JAK2 driver mutation (p < 0.001) and SMF (p < 0.05). NMMIIA aggregates in the RBC correlated with i) SMF (p < 0.01); ii) the evidence of bone-marrow fibrosis regardless the MPN subtype (p < 0.001); and iii) the presence of splenomegaly (p < 0.01).

Conclusion(s): Immunofluorescence on the blood smear unravels morphological alterations of platelets and RBC in patients diagnosed with MPN. Of note, aggregates of NMMIIA in the RBC correlate with the grade of bone-marrow fibrosis and might represent a novel biomarker with accessibility in the peripheral blood that may indicate MPN-progression.