title: In vitro elicitation of cytotoxic response against a nonimmunogenic murine tumor by allosensitization.
abstract: The murine lymphoma (thymoma) PIR-2 of C57BL/6 origin, primarily induced in our laboratory by fractionated X-ray irradiation, has been shown to be nonimmunogenic by its failure to immunize syngeneic mice in vivo or to evoke a cytotoxic response in primary mixed lymphocyte-tumor cell cultures (MLTC) in vitro. We were able, however, to demonstrate the existence of anti-PIR-2 cytotoxic cells among allogeneic-primed C57BL/6 responding lymphocytes using the technique of limiting dilution cultures (LDC). The frequency of anti-PIR-2 cytotoxic cells among C57BL/6 lymphocytes sensitized against BALB/c splenocytes in mixed leukocyte culture (MLC) was 1/20 to 1/40, and the cytotoxic activity of positive LDC wells against PIR-2 reached 60% as determined by a 4-h 51Cr-release assay. The frequency of anti-PIR-2 cytotoxic cells could be increased two- to 10-fold (up to 1/4) by removing nylon-wool-adherent cells from the primed cell population and/or by enriching the primed lymphoblast population on a Percoll density gradient. Anti-PIR-2 cytotoxic cells were found to be Thy1+; Lyt1-2+ cells. Clones isolated from the LDC wells manifested strong cytotoxic activity toward PIR-2 cells and the stimulating BALB/c splenocytes but not against other H-2b tumor lines or C57BL/6 splenocytes. We suggest that the procedure of allostimulation in MLC-LDC is an effective in vitro means of generating highly reactive cytotoxic cells against poorly immunogenic neoplasms.
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D002452:Cell Count; D002999:Clone Cells / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D007959:Lymphocyte Culture Test, Mixed / Q000379:methods*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010641:Phenotype; D051381:Rats; D011917:Rats, Inbred Lew; D013154:Spleen / Q000166:cytology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D013945:Thymoma / Q000276:immunology*; D013953:Thymus Neoplasms / Q000276:immunology*
chemical_list: D000954:Antigens, Surface