ABSTRACT
@#Abstract：Objective To prepare human monoclonal antibody against spike protein（S protein）of severe acute respiratory syndrome coronavirus 2（SARS⁃CoV⁃2）by using single B cell，and determine its neutralizing activity. Methods Venous blood with high antibody level was collected from people immunized with inactivated SARS⁃CoV⁃2 vaccine（Vero cells） twice，of which peripheral blood mononuclear cells（PBMCs）were isolated by lymphocyte stratified fluid and used to isolate single B cell expressing S protein antibody by magnetic beads coupled with S1 protein. Variable region genes of IgG heavy chain and light chain were amplified by nested PCR after reverse transcription of single B cell，which were connected with CMV promoter，IgG leader sequence，IgG constant region and polyA sequence by overlapping PCR to construct antibody linear expression cassette. Linear expression cassette of the heavy chain and light chain from the same B cell was transfected to HEK293T cells to express human monoclonal antibody of SARS⁃CoV⁃2 S protein. Immunoreactivity was detected by immuno⁃ fluorescence while neutralizing activity by pseudovirus neutralization test. Results A total of 26 monoclonal antibodies against SARS⁃CoV⁃2 S protein were expressed，which showed heavy chain and light chain protein bands of IgG antibody at
ABSTRACT
@#[Abstract] Objective: To investigate the expression and clinical significance of PD-1/PD-L1 in gastric cancer (GC) tissues. Methods: Paraffin embedded tumor tissues and clinical data of 82 GC patients who had undergone operation at the Fourth Hospital of Hebei Medical University from January 2007 to December 2007 were collected, and their survival status was followed. The protein expressions of PD-1 and PD-L1 in tumor tissues were detected by immunohistochemistry. Kaplan-Meier analysis and Log-Rank test were adopted to analyze the survival of GC patients, and the ROC curve was plotted. Results: The positive rate of PD-L1 protein expression was 42.68% while the positive rate of PD-1 expression was 13.41% in GC tissues. The positive rate of PD-1 and PD-L1 expression in GC tissues of patients without pre-operative distant metastasis was significantly lower than those patients with pre-operative metastasis (PD1： 3.28% vs 42.86%; PD-L1： 13.11% vs 90.48%; all P<0.01). The positive rate of PD-L1 expression in tumor stroma of patients without pre-operative distant metastasis was significantly lower than those with metastasis (PD-L1: 13.11% v s 47.62%, P<0.01). The resection range of stomach, PD-L1 over-expression and the presence of pre-operative distant metastasis were the adverse factors affecting the prognosis of patients with GC (P<0.05). Conclusion: PD-1 and PD-L1 expressions in GC tissues were closely related to the presence of pre-operative distant metastasis and the depth of tumor infiltration. The postoperative survival of patients who were PD-L1 positive was shorter than the negative ones.