Immune response to polysaccharide antigens in adult patients with recurrent community-acquired pneumonia

The frequency of humoral immunodeficiencies was analysed in 39 patients with a history of recurrent (greater than or equal to 3) episodes of community-acquired pneumonia. Total immunoglobulin levels and/or Ige subclass levels were low in 14 patients (36%), including eight patients with Ige or IgG2 deficiency, The specific antibody activity to pneumococcal capsular polysaccharides (serotypes 3, 6A, 19F, and 23F) and to phosphorylcholine was low in the IgG/IgG2-deficient patients compared to 36 healthy controls, and they also responded poorly to vaccination with a 23-valent pneumococcal capsular polysaccharide vaccine. The remaining 25 patients, with normal immunoglobulin and Ige subclass levels, had specific anti-pneumococcal antibody levels comparable to the healthy controls, and all but 3 responded to vaccination, We conclude that immunoglobulin deficiencies and the inability to respond to polysaccharide antigens are common risk factors for recurrent pneumonia in adult patients, Immunoglobulin levels (including Ige subclasses) and antibody response to polysaccharide antigens should be investigated in these patients.