PURPOSE: To prepare an antibody specifically reactive with proteins on human cell membranes by culturing a fused cell line producing an antibody specifically reactive with the membrane proteins of cloned human cells and fractionating the antibody from the culture mixture.

CONSTITUTION: A congenital immune deficiency mouse which has immune deficiency to glycoside antigen is immunized with human cells or human cell membranes, then the antibody-producing cells of the mouse of immune deficiency to glycoside antigen are fused with myeloma cells. The fused cell line having the ability to produce the antibody specifically reactive with the proteins of human cell membranes is selected and the selected cells are cloned. The cloned fused cell line is cultured and the antibody specifically reactive with the proteins on the human cell membranes is fractionated from the culture mixture. As examples of human cells to he immunized, human tumor cells such as cells of endometrioma, oophoroma, colonic cancer or hepatic cancer are cited.