[Synthesis of ribosomal RNA in the lymphocytes with 21-chromosome trisomy]

Normal and 21-trisomic lymphocytes isolated from whole blood were cultivated with phytohemagglutinin (PHA) for 21 hours and labeled with 3H-uridine. Polysomes were then extracted, using magnesium precipitation. The samples of polysome rRNA were disc-electrophoresed, and the specific activity of the 28S-RNA was determined. In spite of the decreased RNA-synthetic response of the 21-trisomic lymphocytes (determined earlier) the specific activity of the rRNA in the aberrant cells failed to differ from the normal. A decrease in the number of the PHA-responsive cells in the 21-trisomic lymphoid population is supposed.