title: An investigation into the effect of the IgG antibody system on the susceptibility of IgA-deficient patients to respiratory tract infections.
abstract: Serum IgG subclass concentrations and IgG-tetanus toxoid antibody (IgG-TTab) responses were measured in IgA-deficient patients with severe respiratory tract infections (n = 11), mild respiratory tract infections (n = 5) or no increased susceptibility to respiratory tract infections (n = 15). The severe infection group had lower IgG2 concentrations than the patients without infections (P less than 0.02) and was the only group with IgG2-deficient patients (36%). The number of sera in which IgG4 was not detected was higher in patients with severe infections than in both normal controls (45% vs 10%, P less than 0.01) and the other IgA-deficient patients (45% vs 20%), in part explained by a strong association with IgG2 deficiency. Subnormal IgG-TTab responses were demonstrated in 45% of patients with severe infections but in only one patient from each of the other two groups. Five patients with IgG2 deficiency and/or subnormal IgG-TTab responses were treated with gammaglobulin and apparently improved. There was a high serum concentration of IgG1 in 35% and IgG3 in 19% of the 31 patients, predominantly in those without severe infections. Thus a proportion of IgA-deficient patients have additional defects of IgG; IgG1 and IgG3 antibody responses may compensate for the IgA deficiency in asymptomatic patients.
mesh_terms: D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D002648:Child; D004406:Dysgammaglobulinemia / Q000276:immunology* / Q000628:therapy; D005260:Female; D006801:Humans; D017098:IgA Deficiency; D017099:IgG Deficiency; D007116:Immunization, Passive; D007074:Immunoglobulin G / Q000145:classification*; D007136:Immunoglobulins / Q000032:analysis; D008297:Male; D008875:Middle Aged; D012141:Respiratory Tract Infections / Q000276:immunology*; D013745:Tetanus Toxoid / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D007136:Immunoglobulins; D013745:Tetanus Toxoid