Serum monocyte colony-stimulating factor, erythropoietin and interleukin-6 in relation to pancytopenia in hairy cell leukemia.

In patients with hairy cell leukemia (HCL), we measured serum levels of monocyte colony-stimulating factor (M-CSF), interleukin-6 (IL-6), and erythropoietin during various degrees of pancytopenia characteristic for this disease. Serial sera from 12 HCL patients during various stages of the disease were analyzed. No correlation was found between the levels of M-CSF or IL-6 and the numbers of circulating monocytes or platelets, normal values of M-CSF (4 to 10 mg/l), and IL-6 (3-50 U/ml) being detected during all stages of the disease