The effect of pretreatment with allogeneic fetal cells on hamster melanoma

Pretreatment with 7-day embryonic tissue mixed with incomplete adjuvant retarded the growth of melanoma transplants in the Syrian hamster. This effect was not apparent in animals treated with fetal tissue suspension, only or with fetal tissue and complete adjuvant. The inhibitory effect on tumor growth noted in animals challenged with tumor cell doses of 5 x 10(5) or 2.5 x 10(6) cells was abolished when the tumor dose was increased to 5 x 10(6). These results suggest that hamster melanoma and fetal tissue may share a common antigen.