A new transcription factor involved in the transcriptional regulation of early complement components

Abstract

A fluorescence assay for the detection of L-ficolin–MASP in human serum or purified sample was developed by measuring the cleavage of fluorescent amide substrate by L-ficolin associated MASPs bound to the lipoteichoic acid (LTA). LTA (Staphylococcus aureus DSM 20233) was coated on NuncMaxisorp microtiter plates and serum or purified sample incubated overnight at 4 °C to allow the L-ficolin–MASP to bind LTA. Assay conditions for binding and complete cleavage of fluorescent amide substrate were standardized. The optimum temperature, incubation time and molarity of NaCl for LTA–ficolin binding were found to be 4 °C for 6 h at 1 M NaCl concentration. The optimum incubation time and pH for complete cleavage of fluorescent amide substrate by LTA bound L-ficolin associated MASP were found to be 2 h at pH 8.5. LTA–ficolin binding was found to be highly specific and was inhibited completely by LTA but not with mannose. A calibration curve was prepared by using the purified ficolin–MASP complex (1 to 12 μg/ml) and could be used to find concentration of ficolin–MASP complex in normal human serum.