title: Inhibition of haemopoietic stem cells by syngeneic lymphocytes treated with antilymphocyte serum.
abstract: Some aspects of the mechanisms by which antilymphocyte serum, its globulin fraction, or phytohaemagglutinin act to reduce the stem cell content of murine haemopoietic tissues were studied, using the method of clonal proliferation of stem cells in the spleens of lethally irradiated (830R) mice. The transplants were treated in vitro with ALS, ALG or PHA for 30 min. at 37 degrees C. Direct treatment of spleen or bone marrow cells with ALS or PHA resulted in pronounced inhibition of the colony-forming capacity of haemopoietic tissues in syngeneic irradiated recipients. The degree of inhibition was dependent on the concentration of ALS or PHA. It was found that the inhibition of CFC with ALS was mediated by lymphoid cells: bone marrow CFC were reduced after 30-min incubation at 37 degrees C with syngeneic lymph node or thymus cell pretreated with ALG and washed free of its excess. It was further demonstrated that ALG-treated thymocytes released, upon 30-min. incubation at 37 degrees C, some material capable of inhibiting bone marrow CFC. No release was observed with PHA-treated thymocytes. Some properties of the active supernatants are described and it is suggested to designate the observed inhibitory activity as Stem-cell Inhibitory Factor.
mesh_terms: D000818:Animals; D000961:Antilymphocyte Serum; D002455:Cell Division; D002464:Cell Migration Inhibition; D002999:Clone Cells / Q000276:immunology; D005260:Female; D006412:Hematopoietic Stem Cells / Q000276:immunology*; D037102:Lectins; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000276:immunology*; D008263:Macrophage Migration-Inhibitory Factors; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL / Q000276:immunology; D008808:Mice, Inbred CBA / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology
chemical_list: D000961:Antilymphocyte Serum; D037102:Lectins; D008263:Macrophage Migration-Inhibitory Factors