title: Isolation of a low molecular weight inhibitor of lymphocyte proliferation from tumorous ascites.
abstract: Intraperitoneal growth of P-815 mastocytoma cells in syngeneic DBA/2 mice produces ascites fluid which strongly inhibits mitogen-stimulated lymphocyte proliferation. The less than 10,000 m.w. fraction from gel filtration chromatography of tumorous ascites on Sephadex G-150 showed no inhibition of proliferation when eluted under physiologic conditions but was inhibitory when eluted with a high ionic strength, acidic buffer. The organic phase of a chloroform/methanol extract of the low m.w. fraction contained all the inhibitory activity. Purification of the inhibitor to relative homogeneity was achieved by reverse phase, HPLC with a gradient of acetonitrile in dilute acetate buffer. Inhibitory activity eluted between 30 and 35% acetonitrile. The active fraction contained less than 30 pg/ml PGE by RIA which was insufficient to inhibit proliferation and may actually have been stimulatory. Inhibition comparable to that produced by the ascites fraction required greater than 300 pg/ml of PGE. This low m.w. (less than 10,000), lipid-like inhibitor of lymphocyte proliferation is acid stable, not sensitive to proteolytic enzymes, soluble in both aqueous and organic solvents and occurs normally bound to a higher m.w. carrier molecule.
mesh_terms: D000818:Animals; D001202:Ascitic Fluid / Q000032:analysis* / Q000276:immunology; D002460:Cell Line; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D007166:Immunosuppressive Agents / Q000302:isolation & purification* / Q000502:physiology; D008213:Lymphocyte Activation / Q000187:drug effects; D008222:Lymphokines / Q000302:isolation & purification* / Q000502:physiology; D012515:Mast-Cell Sarcoma / Q000032:analysis* / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008970:Molecular Weight; D011458:Prostaglandins E / Q000494:pharmacology; D011863:Radioimmunoassay
chemical_list: D007166:Immunosuppressive Agents; D008222:Lymphokines; D011458:Prostaglandins E