Rapid progression of multiple myeloma in 56-year old man with extensive extramedullary infiltrates after G-CSF therapy has been described. Using the panel of specific antibodies the expression of cytokine receptors, including G-CSF, GM-CSF and IL-6, in autopsy material was examined. No expression of cytokine receptors on tumor cells was found. On the contrary, high positivity of P-glycoprotein and another MDR associated protein - 24-34 kD protein - was observed.

Keywords: MDR, Cytokines, G-CSF, Multiple Myeloma