Severity of infections in IgA deficiency: correlation with decreased serum antibodies to pneumococcal polysaccharides and decreased serum IgG2 and/or IgG4

• Published in: Clinical and experimental immunology Vol. 100; no. 1; pp. 47 - 53
• Main Authors: FRENCH, M. A. H., DENIS, K. A., DAWKINS, R., PETER, J. B.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.04.1995
• Subjects: Adolescent; Adult; Aged; Antibodies, Bacterial - immunology; anti‐pneumococcal polysaccharide antibodies; B cell differentiation disorder; Haemophilus influenzae; Haemophilus influenzae - immunology; Humans; IgA deficiency; IgA Deficiency - complications; IgA Deficiency - immunology; IgG Deficiency - immunology; IgG subclasses; Immunoglobulin G - metabolism; Middle Aged; Polysaccharides, Bacterial - immunology; respiratory tract infections; Respiratory Tract Infections - etiology; Respiratory Tract Infections - immunology; Serotyping; Streptococcus pneumoniae; Streptococcus pneumoniae - immunology
• ISSN: 0009-9104; 1365-2249
• DOI: 10.1111/j.1365-2249.1995.tb03602.x

SUMMARY In order to define abnormalities of humoral immunity which determine susceptibility to respiratory tract infections in IgA‐deficient adults, serum IgG subclass concentrations, and serum concentrations of pneumococcal antibodies and Haemophilus influenzae type B (Hib) antibodies sera from IgA‐deficient adults with and without susceptibility to respiratory tract infections were compared. Infection susceptibility was not related to the degree of IgA deficiency, but was related to deficiency of IgG4 and, to a lesser extent, IgG2, as well as to low basal serum concentrations of pneumococcal polysaccharide antibodies. The combination of IgG2 and/or IgG4 deficiency and a non‐protective basal serum concentration of antibody against two or more pneumococcal polysaccharides was present in the serum of six of 12 (50%) patients with severe infections, but only one of 44 (2%) patients without infections. Furthermore, the preservation of antibody responses against the most immunogenic pneumococcal polysaccharide type 3, but not against the less immunogenic types 7F, 9N and 14, in patients with severe infections suggested that abnormalities of pneumococcal polysaccharide antibody responses might include defects of affinity maturation.