CHARACTERIZATION OF GUINEA-PIG MITOGENIC FACTORS .1. EVIDENCE THAT ANTIGEN-INDUCED MITOGENIC FACTOR AND MITOGENIC FACTOR FROM MIXED LEUKOCYTE-CULTURES ARE DISTINCT MOLECULAR ENTITIES

  • 1 January 1977
    • journal article
    • research article
    • Vol. 119  (6) , 2107-2113
Abstract
Mitogenic factor from BCG-sensitized cells stimulated with antigen (PPD) [purified protein derivative] had a MW between 20 and 25,000 daltons and an isoelectric point of about 7.5. The blastogenic activity of this factor was not affected by L-fucose or heating at 56.degree. C for up to 1 h. Mitogenic factor obtained from supernatants of allogeneic cell mixtures (MLC-MF) had a MW at 15-18,000 daltons and an isoelectric point of 6.5. The blastogenic activity of MLC-MF was inhibited by 0.1 M L-fucose. The factor was stable at 56.degree. C for 1 h. An antibody prepared against MLC-MF inhibited the MLC reaction as well as the activity of MLC-MF on noncommitted cells. This antibody did not affect the response of lymphocytes to PHA [phytohemagglutinin] or PPD and had no suppressive effect on PPD-MF. The antibody was not cytotoxic and its suppressive activity in the MLC response could not be adsorbed out by lymphoid cells, indicating that it is probably directed against a lymphocyte activation product (MLC-MF) rather than membrane antigens. The chemical and immunologic differences exhibited by PPD-MF and MLC-MF indicate that these 2 lymphokines are distinct molecular entities.