Stimulation of human and mouse lymphocytes by ribosomal proteins.

Ribosomal 30S and 50S subunits as well as total proteins from the large subunit of E. coli ribosomes were found to be potent mitogens for both human adult and cord blood lymphocytes. On the other hand, the RNA fraction of the 50S subunit had only a weak stimulatory capacity suggesting that the protein moiety contains the stimulatory component. Experiments with lymphocyte subpopulations obtained by nylon wool filtration of E-rosette separation have shown that, in human, the main target cells are T lymphocytes. First experiments with mouse spleen cells indicate that, in mice, T and B lymphocytes can be stimulated by ribosomal proteins.