The antigen directionally presenting system by MHC-Ⅱ-restricted pathway is designed in order to seek immune tolerance antigens and tumor specific antigens.Developing of this technology is based on following nature principles:The MHC-Ⅱ function that a MHC-Ⅱ subtype is highly affinitive to antigen epitopes with specific anchor resi.dues ;The physiological function of invariant chain (li) which can induce the combination between MHC-Ⅱ and epitopes ; One clone TCR recognizes a single specific epitope; Specific epitope presentation can be achieved by fuse with invariant chain and then direct interact with a specific MHC-Ⅱ subtype to form a MHC-Ⅱ-epitope complex.The complex can be then recognized by the TCR clone that fits this epitope.Thus,it is possible to utilize the epitope-specific TCR to identify the existence of tumor specific antigen.