ABSTRACT
In order to investigate the effects of p-nitrophenylalanine on the differentiation of T lymphocyte,human epidermal growth factor receptor 2(HER2)mutants were constructed by incorporating p-nitrophenylalanine to the extracellular domain of HER2.Mice were immunized with HER2 mutant to analyze the effects of p-nitrophenylala-nine on the differentiation of T cell subsets.The results showed that the immunogenicity of HER2 protein was significantly enhanced by incorporation of immunogenic amino acids.HER2 mutants induced production of more anti-WT-HER2 antibody and greater titer of antibody than PBS and wild-type HER2 in the fifth week.The differ-entiation frequency of Th1 and Th2 cells showed no significant difference,but the differentiation frequency of Tfh cell was found to increase from 4％ to 8％,while the differentiation frequency of Treg cell was found to decrease from 5％ to 1％ through flowcytometry analysis.The gene expression of Bcl-6 and FOXP3 were determined by quantitative real-time PCR.The results showed that the expression of Bcl-6 mRNA increased about 2 fold,while the expression of FOXP3 mRNA could be decreased to about 50％ in HER2 mutant-immunized group.The secre-tion level of IL-21 in serum was also detected to increase from 4 to 28 pg/mL in HER2 mutant-immunized group.The above results confirm that HER2 mutants containing p-nitrophenylalanine can cause an efficient immune response by activating Tfh cell differentiation.