title: Major role of local immune responses in antibody formation to factor IX in AAV gene transfer.
abstract: The risk of an immune response to the coagulation factor IX (F.IX) transgene product is a concern in gene therapy for the X-linked bleeding disorder hemophilia B. In order to investigate the mechanism of F.IX-specific lymphocyte activation in the context of adeno-associated viral (AAV) gene transfer to skeletal muscle, we injected AAV-2 vector expressing human F.IX (hF.IX) into outbred immune-competent mice. Systemic hF.IX levels were transiently detected in the circulation, but diminished concomitant with activation of CD4+ T and B cells. ELISPOT assays documented robust responses to hF.IX in the draining lymph nodes of injected muscle by day 14. Formation of inhibitory antibodies to hF.IX was observed over a wide range of vector doses, with increased doses causing stronger immune responses. A prolonged inflammatory reaction in muscle started at 1.5-2 months, but ultimately failed to eliminate transgene expression. By 1.5 months, hF.IX antigen re-emerged in circulation in approximately 70% of animals injected with high vector dose. Hepatic gene transfer elicited only infrequent and weaker immune responses, with higher vector doses causing a reduction in T-cell responses to hF.IX. In summary, the data document substantial influence of target tissue, local antigen presentation, and antigen levels on lymphocyte responses to F.IX.
authors.affiliation: Department of Pediatrics, University of Pennsylvania Medical Center, Philadelphia, PA, USA.
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.forename: O
authors.initials: O
authors.lastname: Cao
authors.forename: B
authors.initials: B
authors.lastname: Swalm
authors.forename: E
authors.initials: E
authors.lastname: Dobrzynski
authors.forename: F
authors.initials: F
authors.lastname: Mingozzi
authors.forename: R W
authors.initials: RW
authors.lastname: Herzog
mesh_terms: D000260:Adenoviruses, Human / Q000235:genetics; D000818:Animals; D019138:Antibodies, Blocking / Q000276:immunology*; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology; D000229:Dependovirus / Q000235:genetics*; D005164:Factor IX / Q000276:immunology*; D015316:Genetic Therapy / Q000009:adverse effects* / Q000379:methods; D005822:Genetic Vectors / Q000008:administration & dosage / Q000276:immunology; D002836:Hemophilia B / Q000276:immunology / Q000628:therapy*; D006801:Humans; D007273:Injections, Intramuscular; D007371:Interferon-gamma / Q000276:immunology; D015847:Interleukin-4 / Q000276:immunology; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D018482:Muscle, Skeletal / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D014161:Transduction, Genetic / Q000379:methods; D019076:Transgenes
chemical_list: D019138:Antibodies, Blocking; D015847:Interleukin-4; D007371:Interferon-gamma; D005164:Factor IX