Study on the Antigens of Tumor FBL-3:I.Prediction of FBL-3 Antigen and Verification of Antigenicity of Synthetic Peptides / 中国肿瘤生物治疗杂志

ABSTRACT

T lymphocytes play a very important role in tumor immunity, which recognize tumor antigenic peptide presented by MHC molecules on the surface of tumor cells through T cell receptor ( TCR) . Cytotoxic T lymphocytes kill tumor cells after recognizing antigenic peptide in the cleft of MHC class I molecules. It is now generally accepted that peptides naturally presented by a given MHC class I molecule have a specific motif which is referred to as MHC class I allele-specific consensus motif and that synthetic peptide corresponding to the identified naturally presented antigens exhibit remarkable activity in inducing T-cell responses. FBL-3 is a transplantable Friend virus-induced leukemia of B6 (H-2b) origin,which can induce the CTL against FBL-3 by immunizing B6 mice with atenuated FBL-3.Seven peptides were predicted as candidates of FBL-3 antigenic peptides in the light of H-2Db specific peptide binding motif and gag gene sequence of Friend virus. The synthetic peptides, named gagl to gag7, were obtainted. The results showed that CTL specific to gag3 could be induced by in vivo immunizing B6 mice with gag3 in IFA, but a primary T cell response could not be induced by in vitro immuniztion with the peptides. gag3 and gag5 could be recognized by specific CTL to FBL-3,because the CTLs obviously killed target cells (EL-4) pulsed with gag3 or gag5. Immunization with gag3 and gag5 could not induce an immune response to protect the subsequent challenge of FBL-3 in B6 mice which could be induced by immunizing B6 mice with parental FBL-3 tumor cells. This indicates these 7 synthetic peptides may not be the same antigens of the FBL-3.