Security research of cardiac death donation corneas used as penetrating keratoplasty grafts / 国际眼科杂志(Guoji Yanke Zazhi)

To test the safety of using cardiac death donation ( DCD ) corneas for penetrating keratoplasty surgery graft.METHODS:ln chronological order, suing DCD corneas penetrating keratoplasty, corneal endothelial cell density and best corrected visual acuity ( BCVA) were tested 3~4mo after surgery.RESULTS:A total of 14 cases of DCD while 26 corneas were included in this study. Donors age ranged 0. 5 ~61 years, averagely 38. 3 ± 15. 6 years. Causes of death included that 9 cases of traumatic brain injury, 2 cases myocardial infarction, 2 cases brain stem hemorrhage, 1 case of respiratory and circulatory failure. All 26 patients underwent penetrating keratoplasty, no rejection occurred and all grafts were transparent 3 ~ 4mo after surgery. Three to four months after surgery, corneal endothelial cell density ranged 794 ~ 4 347/mm2 , averaged 2 305 ± 827/mm2 , within which was only one case was lower than 1000/mm2 (3. 8%), while 9 cases ranged from 1000 ~ 2000/mm2 (34. 6%), 16 cases were higher than 2000/mm2 (61. 5%). The age of all the 26 receipts were from 20~80 years, mean 40. 7±17. 1 years. BCVA before surgery was light perception positive to 0. 08, with an average 0. 027±0. 024. Three to four months after surgery, BCVA were 0. 2~0. 8, with an average 0. 52± 0. 182 in contrast (t=3. 96, P<0. 001).CONCLUSlON:DCD donated corneas could be used for penetrating keratoplasty graft with high security.

Construction and characterization of soluble HLA-A*0201-PR1 complex / 中国实验血液学杂志

This study was aimed to construct the soluble HLA-A*0201-PR1 complex for preparation of HLA-A*0201-PR1 tetramer. The recombinant HLA-A*0201-BSP (BirA substrate peptide) fusion protein as heavy chain and beta(2)-microglobulin (beta(2) m) as light chain were expressed highly as insoluble aggregates in Escherichia coli and then purified with gel filtration, and the final purity reached above 90%. The two subunits were refolded to form an HLA-A*0201-peptide complex by dilution method in the presence of an antigenic peptide PR1, a HLA-A2-restricted peptide from proteinase 3 (aa 169 - 177, VLQELNVTV). Refolded HLA-A*0201-PR1 complex was biotinylated using a BirA enzyme and purified by anion exchange chromatography on a Q-Sepharose (fast flow) column. The extent of reconstitution of the HLA-A*0201-PR1 complex was analyzed by HPLC gel filtration. The refolded and biotinylated products were detected by Western blot and ELISA with monoclonal antibody BB7.2 that recognized the natural conformations of HLA-A2 and streptavidin. The results showed that the refolded complex was composed of HLA-A*0201-BSP aggregate, HLA-A*0201-PR1 complex and beta(2) m, and reconstitution yields of 18% with PR1 was obtained. Refolded HLA-A*0201-PR1 complex could be confirmed by practical immunological method and biotinylated efficiently. It is concluded that the refolding and biotinylation of HLA-A*0201-PR1 complex is successfully obtained. This work provides the basis for the preparation of HLA-A*0201-PR1 tetramer.

Cloning and expression of HLA-A*0201-BSP / 中国实验血液学杂志

High-yield production of HLA-A*0201 heavy chain is a prerequisite to the preparation of HLA-A2 tetramer. The present study was aimed to construct the expression vector of recombinant HLA-A*0201-BSP fusion gene for preparing HLA-A2 tetramers. The extracellular region HLA*0201 was cloned by RT-PCR from HLA-A2(+) donor, and a 15-amino acid biotin-protein ligase (BirA) substrate peptide (BSP) for BirA-dependent biotinylation was added to the COOH-terminus of HLA-A*0201 heavy chain. Then the fusion gene was cloned into pBV220 vector at EcoRI and Bam HI sites and its sequence was confirmed by DNA sequence analysis. The recombinant plasmid pBV220-HLA-A*0201-BSP was transformed to the competent cells of E.coli DH5alpha. The results showed that the HLA-A*0201-BSP fusion protein was successfully expressed in the form of inclusion body and amounted to over 28% of total cell proteins via induction at 42 degrees C. After washed with triton X-100 and urea, the inclusion body was dissolved with 8 mol/L urea and then purified with Sepharcyl S-300 HR, and the final purity reached above 90%. It is concluded that the HLA-A*0201-BSP fusion gene was cloned successfully and expressed efficiently in E.coli DH5alpha. This work establishes a convenient approach for purification of large quantity of recombinant HLA-A*0201-BSP. This provides the basis for the preparation of HLA-A2 tetramers.

Cloning of Human beta2-microglobulin gene and efficient expression in Escherichia coli / 中国实验血液学杂志

Human beta(2)-microglobulin (beta(2)m) is the light chain of major histocompatibility complex (MHC) class I molecule. High-yield production of this protein is a prerequisite to the preparation of MHC class I tetramer. The present study was aimed to obtain recombinant human beta(2)m expressed in Escherichia coli (E. coli) for preparing MHC class I tetramers. For cloning of human beta(2)m gene, a pair of specific primers was designed based on the published sequence of this gene. A 300 bp specific DNA fragment corresponding to the encoding region of beta(2)m lack of the signal peptide sequence was obtained by RT-PCR from the total RNA of human leukocytes. The amplified cDNA was inserted into the IPTG-inducible expression plasmid pET-17b by Nde I and Bam H I sites and its sequence was confirmed by DNA sequence analysis. The recombinant plasmid pET-beta(2)m was transformed to the competent cells of E. coli BL21 (DE3). The results showed that beta(2)m was expressed in the form of inclusion body and amounted to over 32% of total cell proteins after IPTG induction. After washing with triton X-100 and urea, the inclusion body was dissolved with 4 mol/L urea and then purified with Sephacryl S-200 HR, and the final purity reached above 95%. The denatured protein was renatured by dilution method. Western blot assay indicated that the monoclonal antibody against human native beta(2)m could react specifically with the recombinant protein. In conclusion, the human beta(2)m gene was cloned successfully and expressed efficiently in E. coli BL21 (DE3). This work establishes a convenient approach for renaturation and purification of large quantity of recombinant beta(2)m. This provides the basis for the preparation of MHC tetramers.

Role of B-cell-activating-factor in immune regulation--review / 中国实验血液学杂志

B cell activating factor (BAFF) is one of the TNF family member, regulates the survival and maturation of B lymphocyte. BAFF binds to three receptors: BCMA, TACI and BAFF-R. In recent years, studies have revealed important roles of BAFF and its receptors in immune regulation of antibody isotype switching, germinal center maintenance, and T cell co-stimulation, that may provide new drugs in the future for the treatment of autoimmune disorders, lymphoma and B cell immunodeficiencies. Therefore, the structure, expression, receptors, biological function and clinical application of BAFF are briefly summarized in this review.