title: Soluble factors produced by macrophages/monocytes inhibit lymphokine-activated killer activity in rat splenocyte cultures.
abstract: In the present study we investigated the inhibition of interleukin-2(IL-2)-induced lymphokine-activated killer (LAK) activity in rat splenocyte cultures in relation to the presence of 2-mercaptoethanol and macrophages/monocytes. The presence of 2-mercaptoethanol is necessary for induction of LAK activity in rat splenocyte cultures. Removal of macrophages/monocytes from rat splenocytes by plastic or nylon-wool adherence, or iron ingestion resulted in LAK induction by IL-2 in the absence of 2-mercaptoethanol. The effect of macrophages/monocytes on LAK activity was also studied in transwell co-cultures. In the absence of 2-mercaptoethanol, the induction of LAK activity was very low in macrophage/monocyte-depleted splenocytes with macrophages/monocytes in the upper compartment of a transwell culture. In contrast, in the presence of 2-mercaptoethanol a high level of LAK activity was induced in these transwell cultures, showing that 2-mercaptoethanol abolished the LAK-inhibiting capacity of macrophages/monocytes. In addition, established LAK activity was strongly inhibited when, after LAK induction, splenocytes were cultured with supernatant of unfractionated splenocytes, which were cultured with IL-2 but in the absence of 2-mercaptoethanol. Addition of 2-mercaptoethanol abrogated the inhibiting effect of the supernatant completely. These experiments demonstrate that rat macrophages/monocytes produce 2-mercaptoethanol-sensitive soluble LAK-inhibiting factors. Ultrafiltration of conditioned culture medium of macrophages/monocytes revealed the presence of LAK-inhibiting factors larger than 10 kDa. We concluded that 2-mercaptoethanol-sensitive soluble factors produced by macrophages/monocytes determine the level of LAK induction in rat splenocyte cultures.
authors.affiliation: Department of Pathology, University of Leiden, The Netherlands.
authors.forename: P J
authors.initials: PJ
authors.lastname: Kuppen
authors.forename: A M
authors.initials: AM
authors.lastname: Eggermont
authors.forename: R B
authors.initials: RB
authors.lastname: Quak
authors.forename: A
authors.initials: A
authors.lastname: Marinelli
authors.forename: C J
authors.initials: CJ
authors.lastname: van de Velde
authors.forename: G J
authors.initials: GJ
authors.lastname: Fleuren
mesh_terms: D000818:Animals; D002374:Catalase / Q000494:pharmacology; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D003545:Cysteine / Q000494:pharmacology; D003601:Cytotoxicity Tests, Immunologic; D007376:Interleukin-2 / Q000276:immunology; D015979:Killer Cells, Lymphokine-Activated / Q000187:drug effects / Q000276:immunology*; D008213:Lymphocyte Activation / Q000187:drug effects / Q000502:physiology; D008264:Macrophages / Q000276:immunology*; D008297:Male; D008623:Mercaptoethanol / Q000494:pharmacology; D009000:Monocytes / Q000276:immunology*; D051381:Rats; D017208:Rats, Wistar; D013154:Spleen / Q000166:cytology / Q000276:immunology*; D013482:Superoxide Dismutase / Q000494:pharmacology
chemical_list: D017077:Culture Media, Conditioned; D007376:Interleukin-2; D008623:Mercaptoethanol; D002374:Catalase; D013482:Superoxide Dismutase; D003545:Cysteine