Biological variation of interleukin 6 (IL-6) and soluble interleukin 2 receptor (sIL2R) in serum of healthy individuals

Cytokine. 2000 Sep;12(9):1423-5. doi: 10.1006/cyto.2000.0714.


The biological variation of interleukin 6 (IL-6) and soluble interleukin 2 receptor (sIL2R), measured by automated enzyme immunoassay, in fifteen subjects studied at regular monthly intervals over a period of 6 consecutive months was measured. The mean and standard deviation (SD), within-subject CV, between-subject CV, individuality index (II) and reliability coefficient (R) were as follow: for sIL2R 571 (231) U/ml, 5.84%, 38.81%, 0.21 and 0.93; and for IL-6 1.43 (0.9) pg/ml, 48.48%, 39.38%, 1.44, and 0.37. The data indicate a relatively high between-subject CV, quite similar in both cases, and a within-subject CV much higher for IL-6 than for sIL2R. Thus, reference values can be used for diagnosis for IL6 (high II), while not for sIL2R (low II). However, the low R for IL-6 implies that more than one measurement are needed. sIL2R has a very high R and a relatively small critical differences, a circumstance appropriate for follow-up.

MeSH terms

  • Adult
  • Female
  • Humans
  • Immunoenzyme Techniques
  • Interleukin-6 / blood*
  • Male
  • Middle Aged
  • Models, Statistical
  • Receptors, Interleukin-2 / blood*
  • Reference Values
  • Time Factors


  • Interleukin-6
  • Receptors, Interleukin-2