title: Identification of a human bone marrow-derived immunoenhancing factor, BDEF.
abstract: In this report we describe the production and biological activity of human bone marrow-derived enhancing factor (BDEF). This factor is the constitutive product of cultured human BMC and could initially be recovered by ultrafiltration of cell-free BM supernatants to yield a crude fraction of Mr greater than 10,000 Da. This preparation can enhance the Ab response of human tonsillar cells, as well as murine spleen cells, to SRBC. HPLC fractionation of BM supernatants enriches for enhancing activity in a peak with an approximate Mr of 60 kDa. PAGE gel analysis reveals two protein bands which migrate to this area, one of 60 kDa, and a slightly smaller protein at 55 kDa. Antibodies generated against the above two proteins were shown to be specific by Western blotting and could recognize the native BM proteins as determined by ELISA. The antibodies were used to affinity purify the respective proteins, p60 and p55. The BM protein p60, but not p55, was able to enhance Ab synthesis in vitro and was also mitogenic for murine BMC and thymocytes. The addition of anti-p60 Ab to human tonsillar cells cultured with SRBC and human BDEF preparations resulted in abrogation of enhancement. These findings support the notion that the BM protein p60 is BDEF and that it may represent a novel enhancing molecule produced by normal human BM.
authors.affiliation: Department of Microbiology and Immunology, University of Western Ontario, London, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Mortari
authors.forename: D C
authors.initials: DC
authors.lastname: Saffran
authors.forename: S K
authors.initials: SK
authors.lastname: Singhal
mesh_terms: D000276:Adjuvants, Immunologic / Q000302:isolation & purification; D000818:Animals; D015153:Blotting, Western; D001853:Bone Marrow / Q000032:analysis* / Q000276:immunology; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D006462:Hemolytic Plaque Technique; D006801:Humans; D007120:Immunochemistry; D066298:In Vitro Techniques; D015848:Interleukin-5; D007378:Interleukins / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008934:Mitogens / Q000302:isolation & purification; D011506:Proteins / Q000302:isolation & purification* / Q000502:physiology
chemical_list: D000276:Adjuvants, Immunologic; D015848:Interleukin-5; D007378:Interleukins; D008934:Mitogens; D011506:Proteins; D004247:DNA