RESUMEN
TGFß1 is secreted as latent protein that requires activation to become biologically active. It negatively regulates the progenitor cell growth, and favours the deposition of extra-cellular matrix in different tissues. We have studied TGFß1 levels in Philadelphia-negative (Ph-) myeloproliferative diseases, evaluating patients with primary myelofibrosis (PMF) that is characterized by increased numbers of circulating progenitor cells and bone marrow (BM) fibrosis, and patients with polycythemia vera (PV) or essential thrombocythemia (ET) that do not present BM fibrosis. We found that patients with PMF, PV or ET have higher peripheral blood (PB) plasma levels of both bioactive and total TGFß1 than healthy controls, with a balance bioactive/total TGFß1 in favour of the latter. The balance between bioactive/total TGFß1 in the BM plasma of patients mirrored that of PB, with most of TGFß1 in the latent form; on the contrary, in the BM plasma of healthy controls most of the TGFß1 was in the bioactive form. In conclusion, increased plasma levels of TGFß1 and an altered ratio bioactive/total TGFß1 in BM are not peculiar of patients with PMF suggesting that, whether altered levels of TGFß1 have a role in myelofibrosis, this may not be related to the induction of BM fibrosis.