Influence of the type of treatment on platelet size in patients with myeloproliferative neoplasms.

CELLUCCI AS; MARIN OYARZUN CP; GLEMBOTSKY AC; GOETTE NP; LEV PR; GRODZIELSKI M; BARONI PRIETTO C; HELLER PG; MARTA RF

Congreso; LXII Reunión Anual de la Sociedad Argentina de Investigación Clínica. Reunión Conjunta de Sociedades de Biociencias.; 2017

Myeloproliferative neoplasms (MPN) comprising essential thrombocythemia (ET), Polycythemia vera (PV), and primary myelofibrosis (MF) are frequently associated with thrombotic complications. Current treatments for these entities include hydroxyurea (HU), µ-interferon (IFNa), anagrelide (Ana) and, especially in MF, the JAK inhibitor, ruxolitinib (Ruxo). Considering that large platelets are more reactive and linked to thrombotic events, in this study we investigated possible differences in platelet size in 69 MPN patients grouped according to their diagnosis, mutational status and treatment. Taking into account that cell counters underestimate platelet volume, máximum platelet diameter (MPD) was measured by optical microscopy on May-Grünwald-Giemsa?stained blood films and by software image analysis in at least 100 platelets in each sample. MPN patients had increased platelet size (t test, p=0.0347) but no differences were seen when patients were grouped according to their diagnosis or their mutational status. However, MPD was increased in patients without treatment, 2.67mm(2.19-3.44), n=24, as well as those treated with IFNa, 3.06mm(2.69-3.28), n=8, Ana 2.99mm(2.32- 3.35), n=10, or Ruxo, 3.14mm(2.80-3.52), n=7, compared to patients treated with HU, 2.44(2.19-2.83), (n=22); MPD from IFNa, Ana and Ruxo groups were also higher than normal controls, 2.55mm(2.24- 2.98), n=26 (ANOVA followed by Tukey´s test, p0.0001). In orden to deepen in possible causes underlying these differences, we studied platelet microtubular structure (FITC-anti-tubulin staining and epifluorescent observation). Preliminary data obtained in 11 MPN samples showed a direct correlation between % of platelets with abnormal microtubular rings and MPD (Pearson, r: 0.684, p=0.029). Our results suggest that the type of treatment influence platelet size. The decrease in MPD observed under HU treatment could represent another factor contributing to the beneficial effect of this drug on thrombosis prevention.