In Vitro Cellular Developmental Biology, 25, 243-247, 1989.[PubMed 2925563]

Partial Purification and Characterization of Immunoglobulin Production Stimulating Factor Derived from Namalwa Cells.

Koji Yamada, Kazuhiko Akiyoshi, Hiroki Murakami, Takuya Sugahara, Ichiro Ikeda, Kazuhisa Toyoda, and Hirohisa Omura


We screened for immunoglobulin (Ig) production stimulating factor (IPSF) which enhanced Ig production of human-to-human hybridomas in serum-free culture, and found that culture supernatant and lysate of human lymphoblastoid Namalwa cells stimulated proliferation and Ig production of human-to-human hybridoma HB4C5 cells. The IPSF in Namalwa lysate was partially purified with DEAE-Toyopearl 650M, hydroxylapatite and Superose 6HR 10/30 column chromatographies. The partially purified IPSF was a macromolecule of about 500,000 dalton containing 72,000 dalton protein as a major component. The activity was stable at pH 6 to 12, but inactivated partially by heating over 40 (60% decrease) and completely by trypsin digestion. These results suggest that the IPSF activity is due to its protein and heat-stable components. The Namalwa IPSF stimulated proliferation of human-to-human hybridomas but not that of mouse-to-mouse hybridomas. The IPSF also stimulated Ig production of human-to human hybridomas derived from NAT-30 cells, but not that of other human-to-human or mouse-to-mouse hybridomas. NAT-30 is a human fusion partner derived from Namalwa cells. These results suggest that the Namalwa IPSF is an autocrine factor that stimulates proliferation and Ig production of hybridomas derived from NAT-30 cells.