C3bα链N端42肽促进外源性抗原的交叉呈递

42 residues of the amino terminus of alpha' chain fragment of C3b enhances cross-presentation of exogenous peptides antigens

目的 观察补体C3bα链N端 4 2肽是否可促进外源性抗原的交叉呈递。方法 三种肽 :OVACTL表位 (2 5 7～ 2 6 4 )、C3bAN4 2 OVA2 57～ 2 6 4、OVA2 53～ 2 6 6 用化学法合成 ,然后HPLC纯化、质谱分析。三种肽分别在不同条件下与H 2 b 细胞系ANA 1、RMA S共孵育 ,单抗 2 5 D1.16检测细胞表面OVA2 57～ 2 6 4 Kb 复合物的变化。结果 C3bAN4 2 OVA2 57～ 2 6 4比OVA2 53～ 2 6 6 肽更容易被呈递 ,TAP分子不影响C3bAN4 2 肽的交叉呈递 ,但温度和NH4 Cl对交叉呈递有不同程度的影响。C3bAN4 2 介导的交叉呈递可以提高抗原肽 MHC复合物的稳定性。结论 补体C3bα链N端 4 2肽可促进外源性抗原的交叉呈递 ,并且能延长抗原肽的呈递时间。以上发现可以为肽、蛋白疫苗的设计提供新的启示。

Objective To assess whether the 42 residues of the amino terminus of alpha′ chain fragment of C3b(C3b_ AN42 ) can enhance cross-presentation of exogenous peptides antigens. Methods Three peptides, OVA CTL epitope(257-264), C3b_ AN42 -OVA_ 257-264 and OVA_ 253-266 , were synthesized, and were purified by analytical and preparative HPLC and then characterized by mass spectrometry. After that, peptides were added into murine macrophage cell line ANA-1, TAP-deficient cell(RMA-S)in different circumstances. Monoclonal antibody specific for OVA_ 257-264 /K b, 25-D1.16 respectively was used for counting peptide-classⅠ complexes presented on the cell surface. Results Peptide C3b_ AN42 -OVA_ 257-264 is easier to be presented than OVA_ 253-266 . C3b_ AN42 -mediated cross presentation was not affected by TAP molecule, but was influenced by temperature and NH_4Cl. The stability of peptide-MHC complex was increased by C3b_ AN42 -mediated cross presentation. Conclusion C3b_ AN42 can enhance cross-presentation of exogenous peptides antigens and C3b_ AN42 -mediated delivery of CTL peptides into APCs may prolong antigen presentation. These findings have implications for the design of peptide and protein-based vaccines.