Plasma fibronectin in idiopathic myelofibrosis and related chronic myeloproliferative disorders.

Plasma fibronectin concentrations were measured in 49 patients with chronic myeloproliferative disorders and compared to sex- and age-matched controls. A significantly lower plasma fibronectin concentration was observed in patients with idiopathic myelofibrosis as compared with the control group (p less than 0.01). In addition, plasma fibronectin concentrations in myelofibrosis patients differed significantly, when compared with patients with polycythaemia vera (p less than 0.01), whereas no significant difference was found between myelofibrosis patients and those with a transitional myeloproliferative disorder or chronic myelogenous leukaemia (p greater than 0.05). An inverse relationship was demonstrated between plasma fibronectin and spleen size, the lowest plasma fibronectin levels being found in patients with large spleens. It is supposed that low plasma fibronectin concentrations in splenomegalic patients may be due to enhanced consumption of the opsonin in the expanded splenic mononuclear-macrophage system.