Hematopoietic growth factors stimulate paraprotein isotype production by bone marrow mononuclear cells in an aggressive case of multiple myeloma.

: We describe a patient with multiple myeloma (MM), whose bone marrow (BM) cells were capable of spontaneous paraprotein isotype secretion, which could be strongly stimulated by hematopoietic growth factors (GFs), such as interleukin-6 (IL-6), granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF and IL-3. Ig production by BM cells from another five MM patients and four control patients with non-malignant hematological diseases could not be stimulated by these GFs. The results indicate that GFs, at least in some instances, can activate tumoral plasma cells in patients with MM. This possibility should be taken into account when the utility and effectiveness of GFs in the treatment of MM is evaluated.