Increased numbers of interleukin-15-expressing cells in active ulcerative colitis.
OBJECTIVE
Interleukin-15 (IL-15) is a novel cytokine sharing many of the activities of IL-2. The goal of this study was to evaluate intracellular and serum IL-15 in ulcerative colitis (UC) and Crohn's disease (CD).


METHODS
Intracellular expression of IL-15 in peripheral blood mononuclear cells (PBMC) from UC patients, CD patients, and controls was studied using cell permeabilization and staining with monoclonal antibodies. Serum levels of IL-15 were detected using ELISA.


RESULTS
Percentage of IL-15 expressing PBMC was increased in UC patients and in five of six of CD patients with moderate and severe disease activity compared with controls. The number of IL-15 expressing cells in patients with active inflammatory bowel disease (IBD) declined within 2 wk of treatment. Serum IL-15 reached detectable levels in 62.5% of UC patients with moderate and severe disease activity but not in UC patients with slight disease activity or in remission, neither in CD patients nor in controls. In vitro lipopolysaccharide (LPS)-induced activation of PBMC from controls was associated with up-regulation of intracellular IL-15 expression (p < 0.01) and release of IL-15.


CONCLUSIONS
UC patients with moderate and severe disease activity have increased percentage of IL-15 expressing PBMC, which might be induced by in vivo cell activation and can lead to elevation of released IL-15 in serum. Increased IL-15 expression after in vitro LPS stimulation of control PBMC suggests a nonspecific production of this cytokine during the immunoinflammatory response.
Kirman
I
I
Department of Medical Gastroenterology C, Herlev Hospital, University of Copenhagen, Denmark.
Nielsen
O H
OH
D000328:Adult; D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000276:immunology / Q000378:metabolism*; D003424:Crohn Disease / Q000276:immunology / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015870:Gene Expression; D006801:Humans; D019409:Interleukin-15; D007378:Interleukins / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008213:Lymphocyte Activation; D008297:Male; D013997:Time Factors
D019409:Interleukin-15; D007378:Interleukins