Interleukin 15 activity in the rectal mucosa of inflammatory bowel disease.
OBJECTIVE
Interleukin (IL)-15 has been found to share many immunoregulatory activities in lymphocytes with IL-2. The aim of this study was to investigate IL-15 activity in organ cultures, localization of IL-15 messenger RNA (mRNA), and proliferation of lamina propria mononuclear cells (LPMCs) in response to recombinant IL-15 using the mucosal tissues obtained from patients with inflammatory bowel disease (IBD).


METHODS
The contents of IL-15, tumor necrosis factor alpha, and IL-2 in the culture supernatant of the rectal mucosal tissues were determined by an enzyme-linked immunosorbent assay. Expression of IL-15 mRNA was analyzed by in situ hybridization, and proliferative response of LPMCs to recombinant IL-15 was determined by [3H]thymidine incorporation into DNA.


RESULTS
Significantly greater IL-15 activity was detected in active IBD, and this elevation was also observed in inactive ulcerative colitis. In contrast, greater tumor necrosis factor alpha activity was observed only in active IBD, and IL-2 was not detected in organ cultures. In situ hybridization showed IL-15 mRNA in macrophages and epithelial cells in active IBD specimens, and recombinant IL-15 induced a dose-dependent proliferative response in LPMCs.


CONCLUSIONS
Mucosal IL-15 may be involved in the pathogenesis of IBD as one of the important mediators in activation of mucosal immune cells.
Sakai
T
T
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Kusugami
K
K
Nishimura
H
H
Ando
T
T
Yamaguchi
T
T
Ohsuga
M
M
Ina
K
K
Enomoto
A
A
Kimura
Y
Y
Yoshikai
Y
Y
D000293:Adolescent; D000328:Adult; D000368:Aged; D002455:Cell Division / Q000502:physiology; D003093:Colitis, Ulcerative / Q000378:metabolism* / Q000473:pathology; D003424:Crohn Disease / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D017403:In Situ Hybridization; D019409:Interleukin-15 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D007376:Interleukin-2 / Q000378:metabolism; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins; D012007:Rectum / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D019409:Interleukin-15; D007376:Interleukin-2; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha