Induction of a tumor with greatly increased metastatic growth potential by injection of cells from a low-metastatic H-2 heterozygous tumor cell line into an H-2 incompatible parental strain.

An H-2 heterozygous sarcoma, MDAY, originally induced with methylcholanthrene in an (A X DBA/2)F1 ((H-2a X H-2d) hybrid host was selected for growth in the H-2d homoxygous parental DBA/2 strain by serial intraperitoneal transplantation of ascites tumor cells. An apparent variant, designated MDAY-D2, was obtained which showed the expected loss of the private and public H-2Kk haplotype antigens normally associated with the A strain parent and the original MDAY tumor. Comparison of the original and variant lines revealed a wide variety of a cell surface antigen and receptor differences. Both tumors were found to be highly anaplastic and histologically unclasssifiable. Examination of the two tumor lines growing in vivo revealed a remarkable difference in their metastatic growth potential. The original MDAY line showed little propensity to spread to any organ site, with the occasional exception of liver, after subcutaneous inoculation of (A X DBA/2)F1 mice. In striking contrast, there was a rapid and massive spread of MDAY-D2 to liver, spleen, lungs and kidneys within 12-16 days: liver and spleen could be totally replaced by tumor within 2-3 weeks. These characteristics were observed in both (A X DBA/2)F1 and DBA/2 mice. The tendency to metastasize, as well as loss of the H-2Kk haplotype, appeared stable and irreversible. Although the precise origin of MDAY-D2 is not clear, its metastasizing properties are unique, making it a useful and desirable model to study the biology of metastasis.