A 9-yr evaluation of carrier erythrocyte encapsulated adenosine deaminase (ADA) therapy in a patient with adult-type ADA deficiency
Adenosine deaminase (ADA) deficiency is an inherited disorder which leads to elevated cellular levels of deoxyadenosine triphosphate (dATP) and systemic accumulation of its precursor, 2-deoxyadenosine. These metabolites impair lymphocyte function, and inactivate S-adenosylhomocysteine hydrolase (SAHH) respectively, leading to severe immunodeficiency. Enzyme replacement therapy with polyethylene glycol-conjugated ADA is available, but its efficacy is reduced by anti-ADA neutralising antibody formation. We report here carrier erythrocyte encapsulated native ADA therapy in an adult-type ADA deficient patient. Encapsulated enzyme is protected from antigenic responses and therapeutic activities are sustained. ADA-loaded autologous carrier erythrocytes were prepared using a hypo-osmotic dialysis procedure. Over a 9-yr period 225 treatment cycles were administered at 2–3 weekly intervals. Therapeutic efficacy was determined by monitoring immunological and metabolic parameters. After 9 yr of therapy, erythrocyte dATP concentration ranged between 24 and 44 μmol/L (diagnosis, 234) and SAHH activity between 1.69 and 2.29 nmol/h/mg haemoglobin (diagnosis, 0.34). Erythrocyte ADA activities were above the reference range of 40–100 nmol/h/mg haemoglobin (0 at diagnosis). Initial increases in absolute lymphocyte counts were not sustained; however, despite subnormal circulating CD20+ cell numbers, serum immunoglobulin levels were normal. The patient tolerated the treatment well. The frequency of respiratory problems was reduced and the decline in the forced expiratory volume in 1 s and vital capacity reduced compared with the 4 yr preceding carrier erythrocyte therapy. Carrier erythrocyte-ADA therapy in an adult patient with ADA deficiency was shown to be metabolically and clinically effective.
Document Type: Research Article
Affiliations: 1: Child Health, Division of Clinical Developmental Sciences, St George’s, University of London 2: Purine Research Unit, Guy’s Hospital 3: Department of Clinical Immunology, Royal Free and University College Medical School 4: Respiratory Medicine, Clinical Investigation Unit, Imperial College London, London, UK 5: Department of Medicine, Duke University Medical Centre, Durham, NC, USA
Publication date: October 1, 2007