A PMN-derived factor that enhances DNA-synthesis in PHA or antigen-stimulated lymphocytes.

The DNA synthesis potentiation of a mouse polymorphonuclear leukocyte (PMN) factor was studied by using phytohemagglutinin (PHA)-stimulated syngeneic thymocytes. The partially purified PMN factor was nonmitogenic and exhibited maximum potentiation of thymocytes when added within 3 hr of PHA stimulation. PHA-stimulated, but not nonstimulated thymocytes absorbed PMN potentiation factor. 125I-labeled factor binding to stimulated thymocytes was observed. Our results suggest that an acceptor site for PMN factor may be generated on the thymocyte surface only after PHA stimulation.