ABSTRACT
Objective To set up a system in vitro to rapidly recover plasma proteins lost during artificial-liver treatment.Methods The polyprotein precipitation was obtained by all proteins whose isoelectric point pH value were between 7.3 and 5.1,which collided with each other and aggregated using gradient pH co-precipitation(adding 1 mol/L citric acid slowly in the plasma solution to change the pH values gradually from 7.3 to 5.1 in 5 h)combined with salting out(degree of saturation of NaCl is 33%,reacted for 5.5 h at 4℃)or low-temperature ethanol precipitation(40% ethanol, reacted for 5.5 h at -7℃)so that to get rid of toxicants by discarding the supernatant.Results In the range of pH 5.1-7.3,50%(29g/57g)of the total plasma proteins had been recovered by the gradient pH salting out and 41%(25 g/61g)by the gradient pH low-temperature ethanol co-precipi- tation.The protein remained in the supernatant was mostly albumin and its combined bilirubin.The levels of total bilirubin decreased to 0.07% and 0.06% of the original levels by these two methods respectively and the serum HBV DNA level decreased to be undetected(quantitative PCR).Conclu- sions The proteins with close isoelectric point can co-precipitated with the presence of high concen- tration of NaCl or low-temperature ethanol and by changing the pH value gradually.The total protein in the discarded plasma during artificial-liver treatment can be recovered rapidly using the gradient pH coprecipitation.