the present invention relates to processes which are easily applicable for industrial production of type ii interferon and type ii interferon - containing agents . particularly , the present processes are based on the invention that a large amount of high - titred type ii interferon is easily obtainable by transplanting established human cells in other warm - blooded animal body or inoculating the cells in a culture medium charged in a filter - membrane - interposed diffusion chamber which is designed and fitted in or to the animal body so that the cells can grow on its nutrient body fluid , multiplying the transplanted or inoculated cells in the warm - blooded animal body or the diffusion chamber utilizing the body fluid , then exposing the multiplied cells to the action of a type ii interferon inducer in vivo or in vitro to induce type ii interferon , and purifying and separating the induced type ii interferon . the agents containing type ii interferon obtained by the method disclosed herein are effective and superior for treating and preventing type ii interferon - sensitive diseases .