title: In vitro evidence that subcutaneous administration of glatiramer acetate induces hyporesponsive T cells in patients with multiple sclerosis.
abstract: Glatiramer acetate (GA; Copaxone) is a random sequence polypeptide used in the treatment of relapsing remitting multiple sclerosis (RR MS). We have recently demonstrated that prior to treatment, GA induces proliferation of resting T cells and is not cross-reactive with myelin antigens. Daily GA injections induce a significant loss of this GA responsiveness, which is associated with the induction of highly cross-reactive Th2-type T cells potentially capable of suppressing inflammatory responses. The mechanism of action by which GA induces T cell nonresponsiveness leading to T cell receptor degeneracy in patients with RR MS is unknown. Here, we examined the effects of daily GA administration on the induction of T cell hyporesponsiveness. The frequency of GA-reactive T cells in peripheral blood of seven patients with RR MS was measured by limiting dilution analysis prior to and during 6 months of treatment. In addition, a model in which GA-reactive T cells were stimulated in vitro was developed to better characterize the selection of T cell populations over time. In vivo treatment with GA induced a decrease in GA-reactive T cell frequencies and hyporesponsiveness of CD4(+) T cell reactivity to GA in vitro that was only partially reversed by the addition of IL-2. These data suggest that T cell peripheral tolerance to GA was achieved in vivo during treatment. Thus, our in vitro data suggest that the underlying changes in GA-reactive CD4(+) T cell reactivity could be explained by the induction of T cell anergy and clonal elimination.
authors.affiliation: Laboratory of Molecular Immunology, Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
authors.forename: M
authors.initials: M
authors.lastname: Schmied
authors.forename: P W
authors.initials: PW
authors.lastname: Duda
authors.forename: J I
authors.initials: JI
authors.lastname: Krieger
authors.forename: C
authors.initials: C
authors.lastname: Trollmo
authors.forename: D A
authors.initials: DA
authors.lastname: Hafler
mesh_terms: D000328:Adult; D017951:Antigen Presentation / Q000187:drug effects; D016207:Cytokines / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D005260:Female; D000068717:Glatiramer Acetate; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects; D007279:Injections, Subcutaneous; D007376:Interleukin-2 / Q000494:pharmacology; D008297:Male; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000188:drug therapy* / Q000276:immunology; D010455:Peptides / Q000008:administration & dosage / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology
chemical_list: D016207:Cytokines; D007376:Interleukin-2; D010455:Peptides; D011994:Recombinant Proteins; D000068717:Glatiramer Acetate