Survival of antigen-specific antibody following administration of intravenous immunoglobulin in patients with primary immunodeficiency diseases.

To measure the survival of IgG, IgG subclasses and antigen-specific antibody in immune-deficient patients, we infused 4 patients with X-linked agammaglobulinemia (XLA) and 6 patients with common variable immune deficiency (CVID) with modified immunoglobulin at a dose of 400 mg/kg per month until steady state was reached. Following the 8th monthly infusion, serial samples were obtained and analyzed for serum concentration of IgG, IgG subclasses and for specific antibody activities against a battery of antigens. Half-lives for IgG and IgG subclasses were between 30 and 40 days except for IgG3 which appeared to consist of two populations of molecules, one showing a rapid decay, the other disappearing at a rate suggesting a half life of 22-24 days. Antigen-specific antibodies, including antibodies to HBsAg, cytomegalovirus, pneumococcal polysaccharides and streptococcal group A carbohydrate were similar to that for total IgG. These studies demonstrate that protective antibody titers to infective agents can be maintained for several weeks following high-dose intravenous immunoglobulin infusion.

Increased serum opsonic activity and antibody concentration in patients with sickle cell disease after pneumococcal polysaccharide immunization.

Opsonic defects have been reported in unimmunized patients with sickle cell disease. We found significant increases (P less than 0.001) in serum opsonic activity, measured by a radiolabeled bacterial uptake assay, and in type 7 pneumococcal polysaccharide antibody concentration in 17 such patients 2 years of age or older after pneumococcal polysaccharide immunization. All 17 patients and six healthy controls achieved a type 7 antibody concentration of more than 300 ng antibody nitrogen per milliliter, believed to be the protective level of antibody in vivo. Six patients with sickle cell disease less than 2 years of age did not have a significant increase in type 7 antibody concentration after immunization. Only three of these six patients achieved a postimmunization type 7 antibody concentration exceeding 300 ng Ab N/ml. Overall, 16 of 23 patients with sickle cell disease (70%) had a twofold or greater increase in type 7 antibody concentration, and 13 of these (81%) had a corresponding increase in opsonic activity (P less than 0.001). Thus most patients who responded to pneumococcal polysaccharide immunization had a concurrent increase in opsonic activity in vitro.