NEUTROPHIL FUNCTIONS IN ESSENTIAL THROMBOCYTHEMIA

Chronic myeloproliferative diseases, such as chronic myeloid leukemia and polycythemia vera, are associated with neutrophil dysfunction. Ver y little data is available on essential thrombocythemia (ET). In the c urrent study we evaluated 21 patients with ET. All patients were studi ed at least 16 weeks after any cytostatic therapy and 10 days after an y other therapy. Neutrophil functions were investigated as follows: fl ow cytometric evaluation of whole blood phagocytosis of opsonized FITC -conjugated E. coli; whole blood chemiluminescence after stimulation w ith opsonized zymosan and evaluation by an automated, computer-assiste d luminometer (LB 950, Berthold); and chemiluminescence and superoxide anion generation by purified neutrophils after f-MLP and PMA stimulat ion. Chemiluminescence and superoxide anion generation after f-MLP sti mulation were found to be significantly lower than in normal subjects, whereas values within the normal ranges were registered after PMA sti mulation, Phagocytosis-associated chemiluminescence was found to be im paired both by using zymosan opsonized with autologous plasma and zymo san opsonized with normal plasma, despite a normal phagocytic activity . These data show the presence in ET of a complex neutrophil dysfuncti on that may be related to an impaired signal transduction during both the phagocytic process and f-MLP stimulation.