Proteomic study of the impact of the JAK2-V617F mutation on the phenotype of essential thrombocythemia.

Objective: Previous studies have suggested that two subtypes of essential thrombocythemia (ET) could be separated on the basis of their JAK2 status (V617F-positive or V617F-negative), with a continuum between V617F-positive ET and polycythemia vera (PV). Nevertheless, increasingly contradictory data on the impact of JAK2-V617F (presence and load) on ET phenotype highlight the need for further investigations.

Materials And Methods: We investigated the influence of JAK2-V617F on ET phenotype using mass spectrometry-based analysis of serum protein profiles of ET patients, comparatively with PV patients.

Apolipoprotein A1: A new serum marker correlated to JAK2 V617F proportion at diagnosis in patients with polycythemia vera.

Polycythemia vera (PV) is a myeloproliferative disorder (MPD) characterized by an acquired gain-of-function mutation of the JAK2 protein (JAK2 V617F). Allele-specific quantitative PCR has showed a JAK2 V617F dosage effect on haematological and clinical parameters of PV at diagnosis, but it is unknown whether the level of certain serum proteins might correlate with the proportion of mutated JAK2. Taking into account that such proteins could represent useful prognostic marker, we investigated the serum protein profile of PV patients by SELDI-TOF MS.

JAK2V617F detection and dosage of serum erythropoietin: first steps of the diagnostic work-up for patients consulting for elevated hematocrit.

The predictive values of common biological criteria for the diagnosis of polycythemia vera were studied in a cohort of patients with high hematocrit. We found JAK2V617F and erythropoietin assays were the most relevant first tests. Classification of patients according to their JAK2V617F status and erythropoietin levels facilitated the choice of further diagnostic investigations.

The JAK2-V617F mutation is frequently present at diagnosis in patients with essential thrombocythemia and polycythemia vera.

We determined the allelic frequency of the JAK2-V617F mutation in DNA and assessed the expression levels of the mutant and wild-type JAK2 mRNA in granulocytes from 60 patients with essential thrombocythemia (ET) and 62 patients with polycythemia vera (PV) at the time of diagnosis. Using allele-specific quantitative polymerase chain reaction (qPCR), we detected JAK2-V617F in 75% of ET and 97% of PV at diagnosis. The total JAK2 mRNA levels were elevated in ET, PV, and secondary and idiopathic erythrocytosis, suggesting that hyperactive hematopoiesis alters JAK2 expression.

A standardized endogenous megakaryocytic erythroid colony assay for the diagnosis of essential thrombocythemia.

Background And Objectives: The reliability of assays of endogenous megakaryocytic colony (EMC) and endogenous erythroid colony (EEC) formation for the diagnosis of thrombocytoses remains controversial. We tested the suitability of a recently developed collagen-based assay of EMC formation for the diagnosis of essential thrombocythemia (ET).

Design And Methods: This was a multicenter (8 laboratories) study including 121 patients: 82 with ET and 39 with reactive thrombocytoses (RT).

Standardization and comparison of endogenous erythroid colony assays performed with bone marrow or blood progenitors for the diagnosis of polycythemia vera.

The reliability of the assay of endogenous erythroid colony (EEC) formation in serum-free, cytokine-free collagen-based media was investigated in a multicentric study including 140 patients with polyglobuly (80 polycythemia vera (PV), 54 secondary erythrocytosis (SE), six idiopathic erythrocytosis (IE)) and 10 healthy donors. In each center, EEC assays were performed in parallel with progenitor cells from bone marrow (BM) and peripheral blood (PB); two commercialized media and 'low' and 'high' cell plating densities were tested. Negativity of EEC assays was considered certain only when sufficient BFU-E growth was obtained in control cultures with cytokines.

Standardization of the CFU-GM assay: Advantages of plating a fixed number of CD34+ cells in collagen gels.

We investigated whether plating a stable amount of CD34(+) cells improves the CFU-GM assay. Data of CFU-GM assays performed with leukaphereses products in two transplant centers using a commercial collagen-based medium and unified CFU-GM scoring criteria were pooled and analyzed according to the numbers of CD34(+) cells plated. A first series of 113 CFU-GM assays was performed with a fixed number of mononuclear cells (i.