Rules-Based Medicine

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Interleukin-6 (IL-6)

Ultrasensitive Immunoassay


Rules-Based Medicine’s internally developed and manufactured ultrasensitive  immunoassay for interleukin-6 (IL-6) based on the Simoa® bead technology can accurately quantitate sub-pg/mL levels of IL-6 in serum or plasma; matrices from which existing ELISA-type platforms cannot accurately quantify IL-6.  Such low levels are informative of inflammation status as highlighted by several biologic drugs blocking IL-6 that are  approved or in development for autoimmune, metabolic, cancer and neurodegenerative diseases.

IL-6 is a secreted proinflammatory protein that is part of the IL-6 cytokine family. IL-6 is produced mainly by monocytes, macrophages, dendritic cells, and T cells, but other cells, such as epithelial cells, endothelial cells, fibroblasts, adipocytes, and keratinocytes, are capable of secreting IL-6 under inflammatory conditions. Several agents can induce IL-6 production, including pathogen-associated molecular patterns (PAMPs) such as toll-like receptor agonists and damage-associated molecular patterns (DAMPs) such as mitochondrial DNA. IL-6 signals through binding of either the membrane bound or soluble IL-6 receptor (mIL-6R, sIL-6) as it complexes and activates gp130. Membrane bound IL-6R expression is restricted to immune cells and hepatocytes. However, since nearly all cells express gp130, trans-signaling of IL-6 through binding to the sIL-6R can occur in any cell.

IL-6 promotes induction of other inflammatory cytokines and chemokines and plays a role in recruitment of neutrophils and monocytes, promotion of B cell development, regulation of liver metabolism, and stimulation of tumor cell proliferation, survival and invasiveness. In addition, IL-6, in combination with TGF-β, induces development of TH17) cells and production of IL-17.


Swiss-Prot Accession Number: P05231

Simoa™ Services
Biomarker LLOQ*
(Serum and Plasma)
(Undiluted Samples)
Volume Required
Serum or plasma Other fluids**
Interleukin 6 (IL-6) 0.091 pg/mL 0.0046 pg/mL 50 µL 150 µL

* Lower limit of quantitation (LLOQ) represents the lowest amount of an analyte that can be quantitatively determined with acceptable precision. LLOQ is determined by performing 2-fold serial dilutions of Standard to be tested in triplicate over three runs. The percent coefficient of variation (CV) is calculated for each of the dilution replicates, and the LLOQ is determined as the concentration at which the CV is 30%.

** Cerebrospinal fluid, urine, tissue culture supernatants,  bronchoalveolar lavage, synovial fluid, tissue extracts, tears, skin washings, etc.

All assay services are performed in our CLIA-certified laboratory.
Intended for Research Use Only.