Anti-pneumococcal antibody response in normal subjects: A meta-analysis

Background: The diagnosis of anti-polysaccharide antibody deficiency is based on the presence of normal serum immunoglobulin levels and the lack of specific antibody response to polysaccharide antigens, such as the pneumococcal vaccine. However, a normal response to pneumococcal vaccine is not well defined. ''Modified meta-analysis'' was undertaken in an attempt to define the normal antibody response to pneumococcal vaccine. Methods: Studies identified by a MEDLINE search were selected Data of the normal control groups, rather than the patient groups, were collated for analysis. Results: Twenty-three studies fulfilled the selection criteria. Prevaccination antibody titers, postvaccination titers, and post- to prevaccination titer. ratios varied widely. On the basis of weighted mean ratios, serotype 8 appeared to be the most antigenic. It appeared that normal subjects do not mount a response of even a twofold increase in antibody titer to all the serotypes present in the vaccine. Moreover; no minimal absolute antibody level that could be of diagnostic value, either before or after vaccination, was evident. Conclusion: Response to pneumococcal vaccine among normal subjects varies widely. Better designed and prospective studies are needed to define the parameters of a normal antibody response to pneumococcal vaccine so that uniform guidelines of interpretation can be formulated.