Detection of anti–glutamic acid decarboxylase antibodies in immunoglobulin products

The second patient is a 73-year-old white male with a history of recurrent upper respiratory tract infections, pneumonia, bronchiectasis, and hypogammaglobulinemia with impaired specific antibody production.Because of recurrent infections, the patient required IVIG and has been on this therapy for 15 years.In classical SPS, higher GAD65 antibody titers are usually detected1 compared with what we have observed in our study.[...]the diagnosis of classical SPS should be approached with caution with the lower levels seen in our patients.Patient Sex Age (y) Indication for immunoglobulin replacement Product Route Immunoglobulin dose at time of anti-GAD antibody measurement (mg/kg/mo) Duration of therapy (y) GAD antibody (GAD65) detection (IU/mL) (reference range, 0.0-5.0 IU/mL) 1 F 54 CVID Gammagard 10%∗ IV 480 22 160† 2 M 73 Hypogammaglobulinemia: Low IgG and antibody defects Gammagard 10%∗ IV 500 15 103.8† XLA 1 M 9 XLA Gamunex 10%‡ IV 600 7 3.1§ XLA 2 M 6 XLA Hizentra 20%|| SC 630 5 89.0† XLA 3 M 7 XLA Hizentra 20%|| SC 600 6 77.2† XLA 4 M 5 XLA Hizentra 20%|| SC 533 4 54.9† XLA 5 M 34 XLA Gamunex 10%‡ IV 580 20 93.9† XLA 6 M 39 XLA Gammagard 10%∗ IV 642 30 >250.0† 1 H. Alexopoulos, M.C. Dalakas, Immunology of stiff person syndrome and other GAD-associated neurological disorders, Expert Rev Clin Immunol, Vol. 9, 2013, 1043-1053 2 M. Dalakas, M. Fujii, M. Li, B. McElroy, The clinical spectrum of anti-GAD antibody-positive patients with stiff-person syndrome, Neurology, Vol. 55, 2000, 1531-1535 3 J. Orange, E.M. Hossny, C.R. Weiler, M. Ballon, M. Berger, F.A. Bonilla, Use of intravenous immunoglobulin in human disease: a review of evidence by members of the primary immunodeficiency committee of the American Academy of Allergy, Asthma and Immunology (AAAAI), J Allergy Clin Immunol, Vol. 117, 2006, S525-S553 4 M.D. Kazatchkine, S.V. Kaveri, Immunomodulation of autoimmune and inflammatory diseases with intravenous immune globulin, N Engl J Med, Vol. 345, 2001, 747-755 5 J.K. Abbott, J.A. Church, In vivo assessment of clinically relevant autoantibodies in intravenous immunoglobulin preparations, Pediatr Allergy Immunol Pulmonol, Vol. 23, 2010, 121 6 S. Jolles, S. Deacock, W. Turnbull, R. Silvestrini, C. Bunn, P. White, Atypical c-ANCA following high dose intravenous immunoglobulin, J Clin Pathol, Vol. 52, 1999, 177-180 7 P. Stratta, C. Canavese, P.C. Schinco, B. Montaruli, L. Giorda, P. Bessone, Intravenous immunoglobulin contains detectable amounts of antiphosphol