title: Identification of beta-lymphotoxin as the predominant molecular class of in vitro and in vivo Syrian hamster lymphotoxin.
abstract: The molecular class of Golden Syrian hamster lymphotoxin produced in vitro and in vivo was determined by size-exclusion high-performance liquid chromatography using silica-based protein separation columns eluted with a 0.1 M sodium phosphate, pH 7.4 buffer containing 0.1% Mr 4000 polyethylene glycol. Lymphotoxin cytolytic activity was quantitated in the column effluent by measuring the ability of the fractions to lyse alpha-L929 cells as indicated by [3H]TdR release. Lymphotoxin activity induced by an 8- or 24-hr or 5-day phytohemagglutinin stimulation of peritoneal leukocytes, by 24-hr phytohemagglutinin-coated alpha-L929-cell stimulation of peritoneal leukocytes, or by 24-hr phytohemagglutinin stimulation of spleen cells occurred in the Mr range of 20,000-56,000, with major components in the 35,000-50,000 beta-lymphotoxin region. No activity was present in the complex (greater than 200,000) region and only minimal activity was detectable in the alpha (70,000-160,000) and gamma (12,000-20,000) regions. In vivo-induced lymphotoxin, obtained by peritoneal lavage 48 hr after intraperitoneal administration of phytohemagglutinin, was entirely beta-lymphotoxin and was not detectable in the plasma. Lymphotoxin produced in vitro and injected simultaneously with the gamma-emitting radionuclide 99mtechnetium, inhibited in vivo development of radiation-induced transplacental carcinogenesis. Thus, Syrian hamster lymphotoxin with antitumor activity consists of glycoproteins with isoelectric points of 4.8-5.2, Mr of 20,000-56,000, and major in vitro and in vivo forms in the beta-lymphotoxin range.
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D003602:Cytotoxicity, Immunologic; D005260:Female; D007959:Lymphocyte Culture Test, Mixed; D008233:Lymphotoxin-alpha / Q000145:classification* / Q000494:pharmacology; D008647:Mesocricetus; D008970:Molecular Weight; D009381:Neoplasms, Radiation-Induced / Q000276:immunology*; D010835:Phytohemagglutinins / Q000494:pharmacology; D011247:Pregnancy; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents; D008233:Lymphotoxin-alpha; D010835:Phytohemagglutinins