Decline of vaccine-induced antipneumococcal antibody in children with nephrotic syndrome.

Twenty-five children with steroid-responsive idiopathic nephrotic syndrome were studied for persistence of antipneumococcal capsular polysaccharide antibody during relapse of their disease and at 1, 6, and 12 months after vaccination with the 14-valent pneumococcal vaccine. Nonrelapsers (group I) were compared to those who had at least one relapse but whose sera were obtained during remission (group II). Group II had a more rapid decline in total anticapsular antibody per month than group I (5.3% v 2.4%). Analysis by individual anticapsular types showed that differences between groups approached significance only for type 4 (P = .07). Rates of decline of antibody against pneumococcal capsular polysaccharide varied among types. One year after vaccination, 50% of patients had less than 300 ngAbN/mL against types 4, 6A, 7F, 8, and 19F. Sera obtained from seven patients during relapse had geometric mean antibody concentrations less than 300 ngAbN/mL against those same types; two of these types have been reported to cause disease in vaccinated patients with nephrosis. Decline of antibody against pneumococcal capsular polysaccharide following vaccination varies by capsular type. Type-specific analysis should be used when monitoring serum antibody levels in these patients after vaccination.