Enhanced tumor growth in chimeric mice.

Chimeras were produced by aggregation of B6D2F1 and SWA early embryos. Lewis lung tumor, syngeneic in B6D2F1, was used to study tumor growth and metastases in these chimeras. Enhanced tumor growth, low metastases rate and pronounced enlarged spleen could be observed in SWA equilibrium B6D2F1 chimeras 21 days after inoculation of tumor cells. Increased activity of suppressor T-cells which might be due to permanent allogeneic stimulation in chimeras is discussed as one of the possible mechanisms.