title: Trafficking and activation of murine natural killer cells: differing roles for IFN-gamma and IL-2.
abstract: The repeated ip injection of highly purified recombinant IFN-gamma or IL-2 resulted in a local increase in peritoneal NK activity. This increase in lytic activity was paralleled by increases in the number of peritoneal leukocytes reacting with a rat monoclonal antibody directed against the NK cell-associated surface antigen LGL-1. LGL-1 reacts specifically with the majority of murine NK cells in BALB/c and C57BL/6 mice. A single injection of IFN-gamma induced more peritoneal NK activity at 24 hr than IL-2 on a protein basis. Both cytokines induced increases in the number of LGL-1+ peritoneal cells by 24 hr after injection. Simultaneous injection of suboptimal amounts of IFN-gamma (100 U) and IL-2 (10,000 U) resulted in a significant augmentation of peritoneal NK activity over that observed with either cytokine alone. Also, the peritoneal NK activity generated in response to ip injection of high doses of IL-2 (100,000 U) could be dramatically reduced by simultaneous injection of a neutralizing monoclonal antibody to IFN-gamma. Administration of IFN-gamma 1 day prior to IL-2 resulted in a significant augmentation of the NK activity above that observed with the individual cytokines. In contrast, injection of IL-2 prior to IFN-gamma did not enhance NK activity over that observed with the individual cytokines. Both cytokines must be injected ip for the complementary effects of IFN-gamma and IL-2 on peritoneal NK activity to occur. In contrast, in vitro incubation of peritoneal leukocytes with IFN-gamma resulted in neither a significant enhancement of NK lytic activity nor an increase in the number of LGL-1+ cells. In vitro treatment of peritoneal leukocytes with IL-2 always resulted in significant augmentation of NK lytic activity in the absence of any increase in the number of LGL-1+ cells. These data are consistent with the hypothesis that the local release of IFN-gamma increases peritoneal NK activity by promoting the influx of blood-borne LGL-1+ NK cells from other sites. In contrast, low doses of IL-2 augment the lytic activity of local resident NK cells, whereas high doses of this cytokine induce both an activation of local NK cells and emigration of LGL-1+ NK cells from other sites due to the endogenous generation of IFN-gamma within the peritoneal cavity. Therefore, the local release of IFN-gamma may play an important role in regulating NK cell infiltration in vivo.
authors.affiliation: Biological Carcinogenesis Development Program, Program Resources Incorporated, Frederick, Maryland.
authors.forename: T J
authors.initials: TJ
authors.lastname: Sayers
authors.forename: L H
authors.initials: LH
authors.lastname: Mason
authors.forename: T A
authors.initials: TA
authors.lastname: Wiltrout
mesh_terms: D000818:Animals; D002465:Cell Movement; D003602:Cytotoxicity, Immunologic; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D007113:Immunity, Innate; D007371:Interferon-gamma / Q000008:administration & dosage / Q000502:physiology*; D007375:Interleukin-1 / Q000502:physiology; D007376:Interleukin-2 / Q000008:administration & dosage / Q000502:physiology*; D007694:Killer Cells, Natural / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008815:Mice, Inbred Strains; D009504:Neutrophils / Q000502:physiology; D010529:Peritoneal Cavity / Q000166:cytology
chemical_list: D007375:Interleukin-1; D007376:Interleukin-2; D007371:Interferon-gamma