RAISED URINARY CALMODULIN LEVELS IN IDIOPATHIC MYELOFIBROSIS - POSSIBLE IMPLICATIONS FOR THE ETIOLOGY OF FIBROSIS

Platelet growth factors (e.g. PDGF and TGF-beta) are thought to be pat hogenetically important in the stromal reaction characteristic of idio pathic myelofibrosis (IM). We have investigated a possible pathogeneti c role for a further platelet mitogen, calmodulin. Platelets are rich in calmodulin, of which 30-40% is releasable with a time course that d iffers from alpha-granule proteins. In IM urinary calmodulin concentra tions were 3-fold those of the normals controls. We suggest that an ab normal release of calmodulin may occur from platelets/megakaryocytes i n patients with IM, and that calmodulin should be considered, along wi th other growth factors, in the pathogenesis of marrow fibrosis.