Immunoglobulin treatment in primary antibody deficiency

The primary antibody deficiency syndromes are characterised by recurrent respiratory tract infections and the inability to produce effective immunoglobulin (Ig) responses. The best-known primary antibody deficiencies are common variable immunodeficiency (CVID), X-linked agammaglobulinaemia (XLA), immunoglobulin G (IgG) subclass deficiency, and selective antibody deficiency with normal immunoglobulins (SADNI). Therapy in these patients consists of prophylactic antibiotics and/or Ig replacement therapy. Diagnostic delay remains common owing to limited awareness of the presenting features and may result in increased morbidity and mortality. Replacement therapy with immunoglobulins increases life expectancy and reduces the frequency and severity of infections, but the effect on end-organ damage is still unknown. Both intravenous immunoglobulin (IVIg) and subcutaneous immunoglobulin (SCIg) treatment appear to be safe, with comparable efficacy. A starting dose of 300-400 mg/kg/month in IVIg and 100 mg/week for SCIg is recommended. IgG trough levels should be >5 g/L for patients with agammaglobulinaemia and 3 g/L greater than the initial IgG level for patients with CVID; however, the clinical response should be foremost in choosing the dose and trough level. Infusion-related adverse reactions are generally mild owing to improved manufacturing processes. In this paper, aspects of Ig replacement therapy in primary antibody-deficient patients will be addressed.