@Article{ecn.2010.0203,
AUTHOR = {Amalia Lamana, Ana M. Ortiz, José M. Alvaro-Gracia, Belén Díaz-Sánchez, Jesús Novalbos, Rosario García-Vicuña, Isidoro González-Álvaro},
TITLE = {Characterization of serum interleukin-15 in healthy volunteers and patients with early arthritis to assess its potential use as a biomarker},
JOURNAL = {European Cytokine Network},
VOLUME = {21},
YEAR = {2010},
NUMBER = {3},
PAGES = {186--194},
URL = {http://www.techscience.com/ECN/v21n3/65856},
ISSN = {1952-4005},
ABSTRACT = {As interleukin-15 (IL-15) has been implicated in the pathophysiology of rheumatoid arthritis, we
analysed the serum IL-15 (sIL-15) levels in healthy subjects and patients with early arthritis to establish a
cut-off point that might serve to define elevated sIL-15. This is an initial step to determine whether sIL-15 has
the potential for use as a biomarker for patients with early arthritis. The IL-15 concentration was measured in
serum obtained from 161 healthy controls and from 174 patients with early arthritis, and the relationship
between the expression of the two IL-15 mRNA variants and the sIL-15 levels was also assessed. In healthy
controls, the median sIL-15 value was 0.83 [interquartile range (IQR) 0-8.68] pg/mL; there was no significant
difference in the sIL-15 values according to gender [median level in males was 1.99 (IQR: 0-8.68) pg/mL and
in females 0.50 (0-8.25) pg/mL: p = 0.821]. Moreover, sIL-15 levels did not correlate with age (r = 0.033,
p = 0.685), and they did not display a clear circadian rhythm in healthy donors, with the median values for
IL-15 close to zero at each time tested. In the light of these findings, we considered that sIL-15 was elevated if
its concentration was above 20 pg/mL, since this cut-off point corresponded to the 90th percentile for this
healthy population. We found that 30% of the patients with early arthritis had sIL-15 values > 20 pg/mL. The
levels of sIL-15 did not correlate with disease duration in early arthritis patients, nor did they fluctuate with
changes in disease activity over the follow-up period. In addition, the high level of sIL15 in patients was not
associated with alterations in the alternative splicing of the IL-15 mRNA, favouring the variant that produces
the protein with a long signal peptide for secretion. Serum IL-15 levels were increased in a subpopulation of
patients with early arthritis, indicating that this measure may serve as a biomarker for this condition. Further
studies will be necessary to determine whether the clinical evolution or response to treatment of patients with
high sIL-15 levels differs.},
DOI = {10.1684/ecn.2010.0203}
}