Effects of some polynucleotides on DNA synthesis in human lymphocytes.

The effect of several single-and double-stranded synthetic polyribonucleotides on the 3H-thymidine incorporation in intact and PHA-stimulated human lymphocyte cultures was investigated. Only polyuridilic and polyguanilic acids were found to stimulate DNA synthesis in the intact cells. All other polynucleotides tested had much weaker or had no stimulating activity. PHA-activated lymphocytes responded to addition of polynucleotides by the decrease of 3H-thymidine uptake. The mostly profound inhibition of lymphocyte response to PHA was observed with polyguanilic acid.