Selective abnormal response to Streptococcus pneumoniae heptavalent conjugate vaccine in patients with recurrent infections and normal immunoglobulin concentrations

Abstract

Rationale The persistence of unresponsiveness to polysaccharide antigens in children older than 2 years defines an antibody abnormality. So far, a deficient response to polysaccharide antigens is usually determined by measuring the response to immunization with the 23-valent pneumococcal polysaccharide vaccine, since antibodies to Haemophilus influenzae polysaccharides induced by conjugate vaccines are considered to reflect the ability to respond to proteins rather than to polysaccharides. We have assessed the impact of pneumococcal conjugate vaccine on the evaluation of deficient specific antibody response. Methods As standard part of the evaluation of patients with recurrent infections and/or unusual infections in 58 children (age range 25 mo-59 mo.) the response to immunization with pneumococcal heptavalent conjugate vaccine (Anti-PCP) have been measured. All patients had normal immunoglobulin and IgG subclass levels and were concomitantly tested for total IgG anti-Haemophilus Influentiae, anti-Tetanus and Anti-PCP antibody levels (The Binding Site, UK). Results Anti-PCP deficiency was found in 5/58 patients; 3/5 of these patients had received a second dose with no incremental increase. All 58 patients did have adequate antibody responses to tetanus and Hemophilus i.vaccines. Conclusions The evaluation of the response to pneumococcal conjugate vaccine is a good alternative to the use of pneumococcal polysaccharide vaccine to identify selective antibody defects. Further, this approach might be particularly important with the introduction of heptavalent conjugate pneumococcal vaccine to protect infants and children <2 years of age for a very early high-risk group identification.