Purification and some properties of proliferation suppressing factor from human lung adenocarcinoma PC-8

Extracts by 3 M KCl from a human lung adenocarcinoma cell line, PC-8, suppressed the proliferation of phytohemagglutinin activated lymphocytes. The proliferation suppressing factor (PSF) was purified from the extracts by ammonium sulfate precipitation, gel filtration and ion exchange chromatography. The purified PSF had a molecular weight of 50 kDa by SDS-PAGE and was acid- and heat-labile. Since the PSF also suppressed the proliferation of three established human cell lines, it is unlikely that the PSF hinders the interaction between lymphocytes and mitogens.