Abstract

In order to study the pathogenesis of plasma cell dyscrasias with associated clinical features of chronic neutrophilic leukaemia, the concentration of granulocyte-colony stimulating factor (G-CSF) was measured in a patient, a 73 year old man, who underwent steroid pulse therapy. High G-CSF concentrations and leucocyte counts prior to treatment declined rapidly on administration of dexamethazone, but rose subsequently. G-CSF was not detected in primary cultures of bone marrow cells, but large amounts of interleukin-6 were found in the culture supernatant. These observations suggest that the neutrophilia observed in the patient represented a reactive response to G-CSF secreted from abnormal plasma cells or stromal cells rather than the existence of a genuine myeloproliferative disorder.