Transplantation studies of a putative lymphosarcoma of Xenopus

The fate of the putative transplantable Xenopus lymphosarcoma (M. Balls, Cancer Res., 22: 1142-1154, 1962) was studied under three experimental conditions: (a) xenotransplantation, i.e., transplantation of live "tumor" tissue between adults of Xenopus borealis and X. laevis; (b) inoculation of live "tumor" cells from X. borealis into the blastocoele of X. laevis embryos; and (c) transplantation of "tumor" tissue into recipient adults immunologically unresponsive to the donor tissue antigens. This condition is fulfilled by using X. laevis-X. gilli (LG) hybrids [H.R. Kobel and L. Du Pasquier. In: J.B. Solomon and J.D. Horton (eds.), Developmental Immunology, pp. 229-306. The Netherlands: Elsevier/North-Holland Biomedical Press, 1977] as donors, and triploid X. laevis-X. gilli and X. borealis (LGB) hybrids [C.H. Thiébaud, Dev. Biol., 98: 245-249, 1983] as recipients. In all transplantation experiments, donor and recipient cells could be unambiguously distinguished upon quinacrine staining that yields typical nuclear patterns, for instance bright patchiness in X. borealis, visible also in LGB cells. The results of xenotransplantation between X. borealis and X. laevis indicated that all developing "tumors" were composed of the recipient cell phenotype. The inoculation of live "tumor" cells from X. borealis "tumor" into the blastocoele of X. laevis embryos resulted in "tumor" formation in the recipient tadpoles and in metamorphosed animals. The cell constituting these "tumors" all were of recipient, X. laevis cell phenotype. Finally, "tumor" tissues from LG clones transplanted into LGB hosts were replaced by "tumors" formed of cells with recipient, LGB phenotype. These experiments indicate that this Xenopus tumor-like growth is a transmissible and not a transplantable disorder.