Aim:To explore the biofunctions of human B7-H4 generated from prokaryoticsystem.Methods:The gene of human B7-H4 extracellular region(IgV-like andIgC-like domains)was obtained by PCR from human cDNA FLJ22418 and theninserted into the prokaryotic expression vector pGEX-5X-3 expressing glutathiones-transferase(GST)fusion protein.After being identified by restriction enzymedigestion and sequencing,the recombinant vector was transferred into host strainE coli BL21-RIL(DE3).A 47 kDa fusion protein(GST/hB7-H4)was induced byisopropyl-beta-D-thiogalactopyranoside(IPTG)and purified by standard meth-ods reported in the prokaryotic system.The inhibitory effect of GST/hBT-H4 onproliferation of T cells was observed in vitro by CD3mAb activated T-cell cultur-ing system and [~3H]-thymidine incorporation assay.The concentrations ofinterleukin-2 and iterferon-g in the supernatants of T cells were determined byELISA.Results:We successfully constructed the method for high-level expres-sion and purification of the hB7-H4 extracellular domain as GST fusion proteinfrom E coli.The GST/hB7-H4 fusion protein produced in bacteria had obviousbiological activity to inhibit T-lymphocyte proliferation and IL-2 secretion.Conclusion:The prokaryote expression system could be used to generate hB7-H4 protein with natural spatial conformations and biological functions,whichprovided an efficient and economical way for the preparation of this target protein. Aim: To explore the biofunctions of human B7-H4 generated from prokaryotics system. Methods: The gene of human B7-H4 extracellular region (IgV-like and IgG-like domains) was obtained by PCR from human cDNA FLJ22418 and then inserted into the prokaryotic expression vector The recombinant vector was transferred into host strain E. coli BL21-RIL (DE3). A 47 kDa fusion protein (GST / hB7- H4) was induced by isopropyl-beta-D-thiogalactopyranoside (IPTG) and purified by standard meth-ods reported in the prokaryotic system. The inhibitory effect of GST / hBT-H4 on proliferation of T cells was observed in vitro by CD3 mAb activated T-cell cultur-ing system and [~ 3H] -thymidine incorporation assay. These concentrations of interleukin-2 and iterferon-g in the supernatants of T cells were determined by ELISA. Results: We successfully constructed the method for high-level expres-sion and purificatio n of the hB7-H4 extracellular domain as GST fusion protein from E. coli. GST / hB7-H4 fusion protein produced in bacteria had obvious biological activity to inhibit T-lymphocyte proliferation and IL-2 secretion. Confluence: The prokaryote expression system could be used to generate hB7-H4 protein with natural spatial conformations and biological functions, whichprovided an efficient and economical way for the preparation of this target protein.