Evaluation of the immune response to pneumococcal capsular polysaccharides

Antibody deficiency is the most common immunodeficiency. In 5% to 10% of the patients with recurrent infections that are evaluated for immunodeficiency, a specific deficiency in the immune response to capsular polysaccharides can be found. Patients with recurrent infections should therefore be tested for their capacity to produce antibodies against anti-capsular polysaccharides. As a clinical test, specific antibody levels are measured before and 14 days after immunization with the 23-valent pneumococcal polysaccharide vaccine. In this article we describe the indications, the method used to measure antibodies to capsular pneumococcal polysaccharide and the way the results have to be interpreted.