Figure 2: Production and characterization of anti-BPI polyclonal antibody. (a) Expression and purification of mBPI-N fragment. Lane M: protein molecular weight markers; lane 1: whole cell lysates before IPTG induction; lane 2: whole cell lysates after IPTG induction; lane 3: supernatant of the cell lysates after IPTG induction; lane 4: sediment of the cell lysates after IPTG induction; lanes 5-7: purified mBPI-N using its 6 × His-tag and affinity chromatography. (b) Titer of the polyclonal antibody against recombinant mBPI-N compared with the control pre-immune serum. (c) Specificity of the anti-mBPI-N serum. Purified mBPI-N was probed with preimmune serum, anti-mBPI-N serum and anti-His antibody (1:1000 dilutions each). BPI: bactericidal/ permeability-increasing protein; IPTG: isopropyl β-D-1-thiogalactopyranoside.