Cloning, expression, purification and activity of the hsBLyS

The full length cDNA of human B lymphocyte stimulator (hBLyS) was amplified by using PCR method from cDNA library of human placenta. After purifying and sequencing, the DNA fragment of functional domain of hBLyS (hsDNA fragment) was amplified by using nested PCR method from the PCR product. The prokaryotic expression plasmid pET-30a(+)/hsBLyS was constructed with recombinant DNA techniques after purifying and identifying the hsDNA fragment. Then the plasmid pET-30a(+)/hsBLyS was transformed into λDE3 cells and the recombination protein was found to be highly expressed; the expression product was purified by affinity chromatography gel, Ni²⁺-IDA, made in our laboratory. The experimental results showed that the sequence of the PCR product was identical with the published hBLyS cDNA sequence and purity of the recombination protein we obtained was high. The activity of the purified recombination protein was very significant in the proliferation test of B lymphocytes.