Fate of foreign DNA taken up by tonsillar lymphocytes.

The uptake of heterologous (B. cereus) DNA by tonsillar lymphocytes was followed for 22 hours. Acid-precipitable DNA became associated with the cells as soon as they were mixed with DNA. The uptake was linear from 0 to 3 hours, between 3 to 6 hours part of the cell-associated DNA was released into the incubation medium, and at 22 hours the amount of label in the cells reached the values measured at 2--3 hours. In respect of the size of DNA the uptake seemed to follow the same saturation curve. There was no difference between the uptake pattern of native DNA and that of heat-denatured DNA. The decrease of size of foreign DNA in the cells in the incubation medium was followed by agarose-gel electrophoresis. In tonsillar lymphocytes enzyme activities capable of degrading heterologous DNA were found. The enzyme activities present in the cells could be detected in the culture medium as well for at least 24 hours.