Alloimmunization with Cultured Human Stomach Cancer Cell Lines and the Establishment of Human‐Human Hybridomas Producing Monoclonal Antibodies

Alloimmunization with the cultured human stomach cancer cell lines MKN‐45 and MKN‐28 was conducted and human‐human hybridomas were established. Living MKN‐45 cells (10(7) cells per injection) were injected monthly 34 times into one of the authors (K.K.) over 2 years and living MKN‐28 cells (10(7) cells per injection) were co‐injected 14 times after the 20th injection of MKN‐45 alone. Cultured stomach cancer cells injected subcutaneously into K.K.'s forearm were rejected completely, although they grew transiently at the injection site. All the injections were made voluntarily at the direction of K.K. himself. Two human‐human hybridomas producing monoclonal antibodies reactive with MKN‐45 and MKN‐28 cells, respectively, were separated from a hybridoma of human B‐lymphoblastoid cell line named HO 323/WIL2‐NS and lymphocytes in K.K.'s peripheral blood. One cell line of the hybridoma FMK‐H3 produced IgM‐type monoclonal antibody, and the other line, EMK‐F7, produced IgG‐type antibody. These two human‐human monoclonal antibodies were highly reactive with MKN‐45 and MKN‐28 cells, weakly reactive with MKN‐74 stomach cancer cell line, and not reactive with the other stomach cancer cell lines tested (MKN‐1, MKN‐7, TMK‐1, NUGU‐2, NUGC‐3, NUGC‐4 and KATO‐III).