INTERFERON-GAMMA INVIVO REVERSES THE INCREASED PLATELET LEVELS OF PLATELET-DERIVED GROWTH-FACTOR AND TRANSFORMING GROWTH-FACTOR-BETA IN PATIENTS WITH MYELOFIBROSIS WITH MYELOID METAPLASIA

We previously reported high platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-beta) levels in platelets from patients with myelofibrosis with myeloid metaplasia. We report here the effects of in vivo administration of recombinant human interferon-gamma on these growth factor levels. Of six patients who entered this study in our institution, four completed the 6-month therapy trial with interferon-gamma PDGF and TGF-beta levels in platelets were evaluated before and after treatment. PDGF levels were determined using a radioimmunoassay and TGF-beta activity was measured using an inhibition growth assay on CC164 cells. In these four patients, IFN-gamma therapy led to a reduction of the increased PDGF and TGF-beta levels in platelets towards the normal range. PDGF and TGF-beta values decreased by 25-45% and 32-46%, respectively. An acute deterioration was observed in one patient 5 months after the end of IFN-gamma therapy. In this patient, the deterioration of his clinical state correlated with an increase in intraplatelet PDGF and TGF-beta levels.