The Antibody Responses to Pneumococcal Capsular Polysaccharides in Aged Individuals

Abstract

A population of elderly individuals was studied following immunization with the pneumococcal capsular polysaccharides of types 3 and 8. The antibody responses, determined by indirect hemagglutination (IHA) and by radioimmunoassay (RIA), before and 2 weeks following immunization were compared to those in young adults. Immunoglobulin levels were measured prior to immunization. The numbers of individuals showing a significant increase in antibodies to the polysaccharides of pneumococcal types 3 and 8 were comparable in both age groups when assayed by IHA and RIA. In addition, the mean fold increases in levels of antibodies measured by IHA and by RIA were not significantly lower to either polysaccharide in the elderly group. Postimmunization levels of antibody in the elderly, determined by RIA, were lower to both polysaccharides studied than in young adults, but only those to pneumococcal polysaccharide type 3 differed at a stastically significant level. Comparison of immunoglobulin levels in elderly responders and nonresponders suggested an association between low values of serum IgM and IgA and lack of responsiveness to immunization with pneumococcal polysaccharides.