ANTIGEN-SPECIFIC DELETION OF CLONED T-CELLS USING PEPTIDE-TOXIN CONJUGATE COMPLEXED WITH PURIFIED CLASS-II MAJOR HISTOCOMPATIBILITY COMPLEXANTIGEN

In a previous report, we showed that cloned T cells incubated with sol uble, cognate major histocompatibility complex (MHC) II-peptide comple x internalized the peptide moiety of the complex. Here, we report anti gen-specific deletion of cloned T cells by treatment with soluble, cog nate MHC II-(peptide-toxin) complexes. Toxin (doxorubicin or mycopheno lic acid) was attached to synthetic AcMBP(1-14)Ala4 peptide, an analog of the natural acetylated NH2-terminal segment, AcMBP(1-14), of rat m yelin basic protein (MBP). IA(k)-restricted, AcMBP(1-14)-specific AJ1. 2 and 4R3.9 cloned murine T cells were killed by IA(k)-(AcMBP(1-14)Ala 4-toxin). No killing resulted from incubating A.J1.2 and 4R3.9 cells w ith irrelevant MHC II-(peptide-toxin) or treating IE(k)-restricted, pi geon cytochrome c-specific A.E7 cloned murine T cells with IA(k)-(AcMB P(1-14)Ala4-toxin). T cell receptor-mediated T cell uptake of the pept ide-toxin moiety of relevant complex was blocked by anti-T cell recept or-alpha/beta antibody and by excess toxin-free complex. LD50 determin ations revealed that cognate MHC II-(peptide-toxin) killed T cells muc h more effectively than did peptide-toxin conjugate alone. Finally, T cell uptake of peptide-toxin and intracellular release of toxin occurr ed after incubation with relevant MHC II-(peptide-toxin) containing ra diolabeled toxin. These findings, which provide the first evidence tha t cloned T cells can be deleted with soluble, cognate MHC II-(peptide- toxin) complexes, may have significant clinical relevance for antigen- specific therapy of autoimmune or other T cell-mediated diseases.