Peripheral monocytes and CD4+ cells are potential sources for increased circulating levels of TGF-beta and substance P in autoimmune myelofibrosis.

Myelofibrosis is an uncommon phenomenon associated with a variety of neoplastic and inflammatory processes. Although there is evidence that cytokines elaborated by clonal malignant hematopoietic cells are implicated in myelofibrosis in primary hematologic disorders, there has been little data to date on the pathophysiology of myelofibrosis in autoimmune disorders. Here we report a case of autoimmune myelofibrosis with pancytopenia. Peripheral blood monocytes and CD4-positive lymphocytes produced significantly elevated levels of transforming growth factor beta (TGF-beta) compared to similar cells from healthy volunteer controls. TGF-beta has been implicated in the pathogenesis of myelofibrosis associated with primary hematological malignancies. Furthermore, substance P, previously linked to myelofibrosis, was also detected in elevated levels in the patient's serum and correlated negatively with the levels of the patient's blood counts. These findings suggest a role for both TGF-beta and substance P in the pathophysiology of autoimmune myelofibrosis. This is the first report of deregulated production of TGF-beta by monocytes in the pathobiology of autoimmune myelofibrosis.