title: Selective subnormal IgG3 in 121 adult index patients with frequent or severe bacterial respiratory tract infections.
abstract: We characterized 121 adults with frequent or severe bacterial respiratory tract infections at diagnosis of selective subnormal IgG3. Mean age was 47 ± 13 (SD)y; 87.6% were women. Associated disorders included: autoimmune conditions 33.1%; hypothyroidism 14.9%; atopy 29.8%; and other allergy manifestations 41.3%. In 34.1%, proportions of protective Streptococcus pneumoniae serotype-specific IgG levels did not increase after polyvalent pneumococcal polysaccharide vaccination. Blood CD19+, CD3+/CD4+, CD3+/CD8+, and CD56+/CD16+ lymphocyte levels were within reference limits in most patients. In regression analyses, independent variables age; sex; autoimmune conditions; hypothyroidism; atopy; allergy manifestations; corticosteroid therapy; and lymphocyte subsets were not significantly associated with IgG subclass, IgA, or IgM levels. Frequencies of HLA haplotypes A*01, B*08; A*02, B*14; A*02, B*15; A*02, B*44; A*02, B*57; and A*03, B*07 were greater in 80 patients than 751 controls. We conclude that subnormal IgG3 and non-protective S. pneumoniae IgG levels contribute to increased susceptibility to respiratory tract infections.
authors.affiliation: Department of Medicine, Brookwood Medical Center, Birmingham, AL, United States; Southern Iron Disorders Center, Birmingham, Birmingham, AL, United States; Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States. Electronic address: ironmd@isp.com.
authors.forename: James C
authors.initials: JC
authors.lastname: Barton
authors.affiliation: Department of Medicine, Brookwood Medical Center, Birmingham, AL, United States; Southern Iron Disorders Center, Birmingham, Birmingham, AL, United States; Brookwood Biomedical, Birmingham, AL, United States. Electronic address: luigibertoli@bham.net.
authors.forename: Luigi F
authors.initials: LF
authors.lastname: Bertoli
authors.affiliation: Southern Iron Disorders Center, Birmingham, Birmingham, AL, United States. Electronic address: jbarton205@gmail.com.
authors.forename: J Clayborn
authors.initials: JC
authors.lastname: Barton
authors.affiliation: Southern Iron Disorders Center, Birmingham, Birmingham, AL, United States; Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, United States. Electronic address: rtakma@bellsouth.net.
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Acton
mesh_terms: D001424:Bacterial Infections / Q000097:blood* / Q000276:immunology*; D004198:Disease Susceptibility / Q000276:immunology*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012141:Respiratory Tract Infections / Q000097:blood* / Q000276:immunology*
chemical_list: D007074:Immunoglobulin G
keywords: Allergy; Atopy; Autoimmunity; Human leukocyte antigen (HLA); IgG subclass deficiency (IgGSD); IgG3; IgG3 deficiency; Pneumovax; Respiratory tract infections