Response of human NK cells to IL-6 alterations of the cell surface phenotype, adhesion to fibronectin and laminin, and tumor necrosis factor-alpha/beta secretion.
In vitro effects of human recombinant IL-6 (1-1000 U/ml) on highly enriched human NK CD3-CD56+ cells (94% +/- 2; mean +/- SEM; n = 8), obtained from PBL were studied. IL-6 induced low levels of NK cell proliferation (7- to 30-fold during 6-day incubation), which was IL-2-independent, because IL-6 did not induce detectable IL-2 production by NK cells. Two-color flow cytometry analysis demonstrated that incubation of NK cells with IL-6 at the optimal concentration of 250 U/ml for 6 days significantly increased the proportion of NK cells expressing the following activation Ag: CD25 (26% +/- 17, mean +/- SEM vs 4% +/- 1 in control, n = 5), CD54 (44% +/- 17 vs 9% +/- 3), HLA-DR (29% +/- 13 vs 12% +/- 4), CD69 (45% +/- 7 vs 12% +/- 3), and CD71 (34% +/- 17 vs 6% +/- 2). The mean fluorescence intensity of these activation Ag was increased as well. IL-6 induced expression of CD49b (alpha-chain of VLA-2, 20% +/- 11 vs 2% +/- 1) and CD49c (alpha-chain of VLA-3, 43% +/- 17 vs 5% +/- 3), which are not expressed on resting NK cells. IL-6 also enhanced the fluorescence intensity of beta 1 integrins, CD49d, CD49e, and CD49f, expressed on NK cells. IL-6-stimulated NK cells showed significantly increased integrin-mediated adhesion to fibronectin- or laminin-coated plates (26 +/- 3 mean % cells adhering +/- SEM vs 15 +/- 4 in control for FN and 19 +/- 1 vs 11 +/- 1 for LM, p < 0.05 for both) as determined in a 3 h binding assay. As assessed by inhibition of adhesion using mAb to the VLA-2, -3, -4, -5, and -6, NK cell adhesion to fibronectin was mediated by VLA-4 and 5, and their adhesion to laminin by VLA-3 and -6. NK cells incubated in the presence of IL-6 were found to produce a factor cytostatic to WEHI-164 clone 13 target cells. This effect was partly, although significantly, blocked by neutralizing antibodies to TNF-alpha or TNF-beta. Our data demonstrate that IL-6 can directly activate human NK cells, but is a less potent NK cell activator, for all activation and functional parameters studied, than IL-2.
Rabinowich
H
H
Department of Pathology, University of Pittsburgh, School of Medicine, PA 15213.
Sedlmayr
P
P
Herberman
R B
RB
Whiteside
T L
TL
D015703:Antigens, CD / Q000096:biosynthesis; D000954:Antigens, Surface / Q000145:classification / Q000187:drug effects*; D002448:Cell Adhesion / Q000276:immunology; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D005353:Fibronectins / Q000502:physiology*; D006801:Humans; D016130:Immunophenotyping; D007376:Interleukin-2 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology*; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000276:immunology / Q000502:physiology; D007797:Laminin / Q000502:physiology*; D008213:Lymphocyte Activation / Q000187:drug effects; D008233:Lymphotoxin-alpha / Q000096:biosynthesis / Q000378:metabolism*; D016029:Receptors, Very Late Antigen / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000378:metabolism*
D015703:Antigens, CD; D000954:Antigens, Surface; D015815:Cell Adhesion Molecules; D005353:Fibronectins; D007376:Interleukin-2; D015850:Interleukin-6; D007797:Laminin; D008233:Lymphotoxin-alpha; D016029:Receptors, Very Late Antigen; D014409:Tumor Necrosis Factor-alpha