CHARACTERIZATION OF PNEUMOCOCCAL SPECIFIC ANTIBODIES IN HEALTHY UNVACCINATED ADULTS

Unlike the elderly healthy middle aged adults are at relatively low ri sk of acquiring serious pneumococcal disease, An explanation that has been proposed is that people in this age group have significant amount s of serum antibody (primarily IgG2) that react with many pneumococcal capsular polysaccharide serotypes, The level of antibody can be as hi gh as several hundred micrograms per milliliter of blood for some sero types, A significant component of this reactivity is directed coward t he conserved C-polysaccharide depletion, Even after C-polysaccharide d epletion, which is included as a routine part of the assay to determin e antibody levels, resting antibody levels in a normal healthy adult p opulation can vary widely. We have analyzed the reactivity of serum fr om 76 people to 16 pneumococcal capsular polysaccharide serotypes, The antibody, reactivities to 13 of 16 serotypes are highly correlated wi th one another Depletion of serum with C-polysaccharide and purified c apsular polysaccharide inhibited antibody binding to type specific cap sular polysaccharide, Cross-serotype inhibition of antibody binding wa s also observed. This indicates that there are materials contained wit hin the pneumococcal polysaccharides that contribute to the cross-reac tivity of serum antibodies in people that have not been vaccinated wit h the pneumococcal vaccine. (C) 1998 Elsevier Science Ltd, All rights reserved.