Does anyone have a combo of antibody clones that will detect both soluble TNF-alpha and TNFR1-bound TNF-alpha for an ELISA assay.  More details below...

In a murine model that I use, neutralization of TNF-alpha mediates survival and reduced disease in contrast to IgG treatment.  However, I cannot seem to find appreciable amounts of soluble TNF-alpha via ELISA.  

So I am predicting that there is a lot of either membrane-bound TNF-alpha or TNF-alpha in conjunction with soluble TNFR1.  While I have other experiments in the works to look at membrane-bound TNF-alpha, and I could set up other experiments to examine TNF-alpha signaling in other assays.  However, I would like to determine if there are any TNF-alpha-sTNFR1 complexes in my current samples.