Correlation of growth morphology and clonability with malignancy of WEHI-7 T-cell lymphoma sublines

This study examined the development of subclones of different proliferative capacity and malignancy in the WEHI-7 tumor. The mouse T-cell lymphoma WEHI-7 can be cloned in agar with a cloning efficiency of 40 to 50%. On the basis of growth morphology, two types of colonies were distinguished. Most colonies were compact, but a few, no more than 5%, were diffuse. Sublines of the two colony types were established. The cloning efficiency in agar was 40 to 50% for the compact and 15 to 25% for the diffuse sublines. The recloning efficiency did not change for compact colonies. In contrast, the cloning efficiency of diffuse colonies decreased with repeated reclonings. The mice died within 24 to 34 days of i.v. injection of 10(4) WEHI-7 cells. The same number of cells of the individual sublines administered to mice resulted in improved survival. Injection of compact subline cells resulted in death in 24 to 48 days, while diffuse subline cells resulted in death in 30 to 75 days. The sublines were indistinguishable by light and electron microscopy. Both subline types were negative for terminal deoxynucleotidyl transferase and positive for Thy 1.2. Most cells from the two types of sublines were Lyt-1 and Lyt-2 positive. The doubling time was 10 hr for compact and 14 hr for diffuse sublines. Colony morphology was conserved after passage in vivo and after more than 10 transfers in vitro in liquid and agar media. In conclusion, the different growth morphology in vitro distinguished the subclones of different malignancy in the WEHI-7 tumor cell line.