NEW MATERIAL:A fused polypeptide composed of a human colony-stimulating factor polypeptide and human interleukin-6 polypeptide.

USE: An auxiliary therapeutic agent for recovery from the decrease of neutrophil of platelet in the therapy of cancer or in bone marrow transplantation.

PREPARATION: For example, from a human thyroid gland-derived cell line NIM-1 (FERM P-11103) producing interleukin-6 and a colony-stimulating factor, the whole RNA is prepared by using the guanidium thiocyanate method. mRNA is separated by using an oligo-dT cellulose column and the cDNA library is formed thereby. A clone containing DNA coding interleukin-6 and the colony- stimulating factor respectively is selected therefrom by cloning and the respec tive exon parts of these DNA are mutually combined. The combined DNA is incorporated into a vector and intransduced into an eucaryotic cell to trans form the cell. The resultant transformed cell is cultured, thus obtaining the objective fused polypeptide.