Human dialyzable leukocyte extracts (DLE) have been used for the last 50 years to successfully treat different diseases. They are obtained by disruption of cells in buffy coats and subsequent dialysis (<12 KDa) of the extracts. They can transfer cellular immune response from an immune donor to a naïve recipient, and despite their immunomodulatory effect, until now little is known about their mechanism of action. One possibility is that they may contain ligands that activate TLRs. In this work using a reporter gene assay and HEK293 cells transfected with either TLR-2 or TLR-4 plasmids, we showed that different concentrations of DLE (100, 10 and 1 microg/mL) resulted in the activation of NF-kappaB (luciferase reporter system) in cells TLR-2 transfected cells with 10 or 1 microg/mL DLE. Interesting none of the DLE concentrations used induced a significant luciferase activity in the TLR-4 transfected cells. Our result can explain in part the immunomodulatory effects produced by DLE both in vivo and in vitro. Work will now focus in the identification of this ligand(s).
This work was supported in part by SIP/IPN. 1Are fellows of COFAA, EDI and SNI.