A human choriocarcinoma xenograft in nude mice; a model for the study of antibody localization.

The successful development of the concept of linking cell-killing agents to tumour-specific antibodies will be largely determined by the extent to which the antibodies are preferentially localized in the malignant tissue. A xenograft of human choriocarcinoma (CC3) has been established in nude mice, and the relative distribution of affinity-purified specific antibodies to human chorionic gonadotrophin has been compared with that of nonspecific antibodies from the same species. Treatment of the nonspecific antibodies with ammonium thiocyanate appeared to be important to ensure that the distributions in normal nude mice were equivalent. Specificity indices, derived from the comparative distributions of isotope activity in the tumour and lung of labelled specific and nonspecific antibodies, ranged between 1.3 and 2.0.