50 ion exchanger previously equilibrated with a 0 05 m phosphate buffer solution ph 6 5 to adsorb impurities onto the ion exchanger the effluent 10 l was concentrated by diaflow hollow fiber concentrating apparatus do 30 model manufactured by amicon co ltd and the concentrate was subjected to dialysis against a 0 1 m tris hcl buffer solution ph 7 0 at 5 u00b0 c overnight in the same manner as described above the same buffer solution was added to the non dialyzed liquid to make 3 liters the resulting solution was passed through a column 4 0 u00d7 40 cm of deae cellulose which had been activated and equilibrated with the same buffer solution after thoroughly washing the column with a 0 1 m tris hcl buffer solution ph 7 0 the column was eluted with a 0 1 m tris hcl buffer solution ph 7 0 containing 0 3 m sodium chloride fractions having a stimulating activity on the differentiation and proliferation of granulocyte were collected and dialyzed against a 0 1 m tris hcl buffer solution ph 7 0 the non dialyzed liquid was again passed through a column 4 0 u00d7 40 cm of deae cellulose which had been equilibrated with the same buffer solution and eluted with a linear concentration gradient of from 0 1 to 0 3 m nacl fractions having a stimulating activity.