Specific antibody deficiency (SAD) is a humoral immunodeficiency characterized by normal levels of IgG, IgA, IgM and IgG subclasses but a failure to polysaccharide antigens, manifested with recurrent bacterial respiratory infections. To establish the SAD diagnosis an inadequate IgG antibody response to more than 50% of pneumococcal serotypes after unconjugated pneumococcal immunization are needed. An adequate response is defined as a post-immunization titre of ≥1.3 μg/ml or ≥four times the preimmunization value.(1;2)
Methods:
The record of 1 patient was review and relevant clinical data was collected. A review of the literature about SAD was made.
Results:
A 4-years old male with family history of atopic disease, esophageal reflux at 3-months old, he began with recurrent upper respiratory tract infections at 1-year old, 1-2 events per month, fever (39-40º C), persistent cough and hyaline rhinorrhea, nasal itching and sneezing he was treated with multiple antibiotics, inhaled and oral corticosteroids with mild clinical recovery between episodes. A normal blood cell count, and normal levels of IgG 1219 mg/dL, IgA 146 mg/dL, IgM 98 mg/dL and IgG subclasses were determined. Allergic rhinitis and asthma were diagnosed at 3-years old, percutaneous prick skin test was positive to Dermatophagoides farinae, Salsola pestifer, Phleum pratense, Heliantus sp. and specific immunotherapy was started. Despite of treatment he continued with recurrent infections so specific antibody response to polysaccharide pneumococcal antigens was evaluated, he responded less than 50% to 14 pneumococcal serotypes after 23-valent unconjugated pneumococcal vaccine, so SAD was diagnosed and treated with prophylactic antibiotic, pneumococcal polysaccharide conjugated vaccine (10-valent) and specific immunotherapy. He showed clinical improvement, with few mild infections, and controlled rhinitis and asthma.
Conclusions:
There are several Primary Immunodeficiency Diseases related to allergic diseases as IgA deficiency and SAD. In the atopic patient that does not improve in spite of specific immunotherapy further investigations are needed to exclude them.
References
(1) Yong PF, Chee R, Grimbacher B. Hypogammaglobulinaemia. Immunol Allergy Clin North Am 2008; 28(4):691-713, vii.
(2) Boyle RJ, Le C, Balloch A, Tang ML. The clinical syndrome of specific antibody deficiency in children. Clin Exp Immunol 2006; 146(3):486-92.