VARIABILITY IN THE SENSITIVITY OF 9 ENZYME-LINKED IMMUNOSORBANT ASSAYS (ELISAS) IN THE MEASUREMENT OF HUMAN INTERLEUKIN-6

ELISAs employing several combinations of polyclonal and monoclonal ant i-human IL-6 antibodies for the detection of interleukin 6 (IL-6) in c ell culture supernatants were developed and compared. They were found to have differing sensitivities in the measurement of standard prepara tions of recombinant human (rh) IL-6 (WHO reference standard) as well as conventional preparations of IL-6 produced by stimulated human peri pheral blood mononuclear cells. Thus, an ELISA that was optimal for de tecting rhIL-6 standard was suboptimal for detecting IL-6 in cell cult ure supernatants. The presence of soluble IL-6 receptor (sIL-6R) or th e signal-transducing gp130 molecule or serum did not alter the levels of IL-6 detected by these ELISAs. Therefore, the observed variability in sensitivity of the assays may be due to differences in epitope spec ificity of the various monoclonal antibodies used and the heterogeneit y of IL-6 secreted into culture supernatants. Published by Elsevier Sc ience B.V.