Detection of soluble type II receptor in the presence of its natural ligand IL-1 beta. Quantification by sandwich ELISA.
The type II interleukin-1 receptor (IL-1R II) is a newly described 60-68 kDa protein expressed on monocytes, neutrophils, and lymphocytes. It is hypothesized that a 45 kDa soluble form of the IL-1R II attenuates the proinflammatory effects of IL-1 by preventing its binding to the type I IL-1 receptor. However, very little information exists regarding the detection of soluble IL-1R II. Specifically, there are no reports to date characterizing IL-1R II detection by enzyme-linked immunoassay in the presence of IL-1 beta or characterizing IL-1 beta detection in the presence of IL-1R II. This study addresses the detection and quantitation of IL-1R II and IL-1 beta by a number of sandwich ELISA formats and characterizes the sensitivity of detection in the presence of competitive cytokines. We generated two distinct IL-1R II sandwich ELISAs that can detect receptor down to a level of 50 pg/ml. One, M22/R2, detects only unbound IL-1R II and the other, M2/R2, detects both bound and unbound IL-1R II. In this context, a 4:1 molar ratio of IL-1 beta to IL-1R II interferes with the IL-1R II detection by the M22/R2 but not the M2/R2 ELISA. Conversely, IL-1R II at physiologically relevant concentrations interferes with the detection of IL-1 beta by three distinct IL-1 beta ELISA formats. Taken together, these studies suggest that when measuring samples that may contain both IL-1 beta and IL-1R II, careful attention must be given to assay specificity.
Altenberger
E A
EA
Department of Internal Medicine, Ohio State University, Columbus, USA.
Pope
H A
HA
Wewers
M D
MD
D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D007375:Interleukin-1 / Q000737:chemistry; D008024:Ligands; D017472:Receptors, Interleukin-1 / Q000032:analysis* / Q000737:chemistry; D011994:Recombinant Proteins; D012995:Solubility
D007375:Interleukin-1; D008024:Ligands; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins