Rapid decline of anti-pneumococcal antibody levels in nephrotic children.

Nephrotic children are at increased risk for pneumococcal infections. Antibody responses to the currently recommended pneumococcal polysaccharide vaccine have been variable and maintenance of adequate antibody levels over time has not been well documented. In this study, we determined total IgG antibody levels against pneumococcal polysaccharides before and 1, 6, 12 and 36 months after 23-valent pneumococcal polysaccharide vaccine (PPV) administration in nine children with steroid-responsive nephrotic syndrome during remission while off corticosteroids. The baseline antibody levels were between 4 and 86 mg/l. Four weeks after vaccination, the titer increased at least twofold in all patients with a mean arithmetic value of 165.4 mg/l. At the 6th month, the levels decreased in six out of nine subjects to a mean of 94.6 mg/l. At the 36th month, the control antibody levels were below the baseline or below the early postvaccination values in four out of nine subjects. Only two patients had stable high concentrations through the study period. Our data show that nephrotic patients may not retain their antibody levels despite reasonably good initial responses to the pneumococcal vaccine and that susceptibility to infections may continue in vaccinated children.