Leukaemic transformation of f1-hybrid cells after inoculation of parental leukaemic cells.

An aneuploid chromosomal anomaly was observed in more than 90% of the mitoses of a spontaneous acute lymphatic leukaemia in C57BL/6J mice preserved by passage in the strain of origin since 1967. The leukaemia is strain-specific and causes the death of its recipients within 9 days. After repeated transfers within F1-hybrids tagged with the T6-marker chromosome, mitoses containing both the chromosomal anomaly of the leukaemic cells and the T6-marker of the semiallogeneic host were observed. This evidence of malignant transformation is compared to leukaemic transformation as observed after clinical bone marrow transplantation.