Ribonucleic Acid Synthesis in Rabbit Lymph Node Cells

Suspensions of lymph node cells were prepared from immunized and from unimmunized rabbits. In a totally synthetic medium at 37°C, these cells incorporated 3H-uridine into RNA at an initially rapid linear rate without lag. After 60 to 90 min of incubation, the rate of uridine incorporation changed to a second linear rate which was about 9% of the initial rate. Maximal initial rates of 3H-uridine incorporation were observed 5 days after immunization, though differences were small between cells from immunized and nonimmune animals. Sucrose gradient analyses of whole cell RNA revealed that the major classes of cellular RNA contained significant radio-activity and antigen-stimulated cells revealed predominant labeling in a 12 to 13S fraction. These experiments provide a reasonable approach to the preparation and isolation of high specific activity RNA for use in the RNA-DNA hybridization studies or in the functional characterization of various classes of RNA implicated in immune responses.